[Index]
Monthly Global Tropical Cyclone Summary July 2003
[Summaries and Track Data] [Prepared by Gary Padgett]
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Monthly Global Tropical Cyclone Summary July 2003 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
JULY, 2003
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
*************************************************************************
JULY HIGHLIGHTS
--> First Atlantic hurricane of season strikes Texas
--> Several weak Eastern Pacific tropical storms form
--> First super typhoon in five years strikes Philippines--also strikes
southern China
--> Minimal typhoon affects southern Philippines, China and Vietnam
*************************************************************************
***** Feature of the Month for July *****
FORECASTING AUGUST ATLANTIC TROPICAL CYCLONE ACTIVITY
-----------------------------------------------------
This monthly feature is based upon research conducted by Eric S.
Blake, currently an employee of TPC/TAFB, and formerly a graduate
research student at Colorado State University, Fort Collins, CO.
A special thanks to Eric for granting permission to feature his
work in this summary. Much of the information was taken from the
abstract of Eric's paper appearing in the book from the AMS 25th
Conference on Hurricanes and Tropical Meteorology, held in San
Diego, CA, in April-May, 2002.
It has been 20 years since Dr. William Gray of Colorado State
University (CSU) began his pioneering efforts in forecasting seasonal
levels of tropical cyclone activity in the Atlantic basin. The CSU
seasonal forecasts show skill in the 3-10 month time frame in
predicting overall seasonal activity. However, significant month-to-
month and multi-week variability exists within most seasons. Very
active hurricane seasons may contain quiet 2-4 week periods, while
inactive years can exhibit short active periods.
(NOTE: In the discussion below I have freely used the terminology
employed in the CSU forecast, e.g., NS, H, IHD, NTC, etc. A definition
of these terms can be found in last month's (June) monthly feature.
Also, all the NTC values referenced in this article are based on the
period 1950-2002.)
A few examples of this intraseasonal variability follow:
(1) 1995 - During the hyper-active 1995 Atlantic season (19 NS, 11 H,
5 IH), there were two very active periods separated by a long
quiet period. Between 28 July and 29 August, nine NS formed
(Dean through Luis), and from 27 September to 27 October, six
NS developed (Noel through Tanya). However, between 29 August
and 27 September, only one cyclone developed--Marilyn.
(2) During the inactive 1941 season (6 NS, 4 H), no tropical storms
or hurricanes were detected prior to 11 September. However,
between that date and 15 October, all of the season's six NS
developed.
(3) In 1976, which was a below-normal year in the Atlantic (NTC of
81), the month of August was very active, producing five NS with
a NTC of 59. Prior to August, one minor storm developed, and
following August, there were only two more NS. That year
experienced a very quiet September with only one NS forming
during the month.
(4) During the period 1950-2002, there were two Augusts with zero
tropical cyclone activity: 1961 and 1997. Yet the character
of these two seasons was drastically different. The stormless
August of 1997 had been preceded by a very active July with four
NS, but only three more storms followed after August, yielding a
very low NTC for the season of 51. However, the storm-free August
of 1961 was followed by one of the most active Septembers on record,
and that year's NTC of 212 is exceeded by only 1995 (220) and
1950 (229).
(5) The year 1966 experienced a very active early season with five NS
forming by late July. Yet, the month of August produced only one
storm, Hurricane Faith, followed then by four NS in September.
(6) The year 1981 was a very spread-out year, with tropical storm
activity beginning with Arlene in early May and continuing through
early November when Hurricane Katrina formed. The seasonal NTC
was 108, slightly above normal, but nearly 80% of this total NTC
occurred during the month of September alone, when five hurricanes
developed--there were hardly any days during the month in which
there was not a tropical cyclone operating.
Since there were no operational techniques for predicting the
occurrence of Atlantic tropical cyclones above or below climatology
over periods of a few weeks to a month, Eric set out a few years ago
to see if one could be developed. He chose the month of August
because of its large average NTC (25%) and large year-to-year
variability. He has developed a forecast procedure which explains
about 55-70 percent of the variance of August tropical cyclone activity
one month in advance using regression techniques. This is substantially
better than simply climatology, or by assuming that in a given year
August will produce 25% of the activity of the CSU seasonal forecast.
Some of the atmospheric predictors identified by Dr. Gray in his
seasonal forecasts were first utilized in a provisional first trial
for forecasting August NTC. This set failed to produce skillful fore-
casts, and it was immediately clear that a new set of predictive
factors would be required to produce skillful August-only forecasts.
Eric's analysis utilized NCEP re-analysis fields for the years 1949-
1999 to identify potential predictors. Another group of provisional
predictors was found by correlating tropical cyclone activity indices
with global re-analysis atmospheric fields for 1958-1999.
Eric developed hindcast schemes for the 1949-1999 period using the
best predictors for each of the dependent variables. Twelve parameters
were determined to be related to some aspect of August tropical cyclone
activity. The two most-utilized predictors, appearing in every fore-
cast equation, are the westerly and southerly July 200-mb winds over
the equatorial Pacific just west of South America. When this region
experiences winds that are anomalously westerly and southerly, tropical
cyclone activity is generally suppressed in the Atlantic basin. This
predictor is linked to ENSO, mid-latitude features in the Southern
Hemisphere, and the Madden-Julian Oscillation.
Increased August Atlantic basin activity usually follows anomalously
low pressure in the mid-latitudes of the western Pacific Ocean and high
pressure in the western Pacific tropics. During the early summer before
active Augusts, the Atlantic experiences a reverse synoptic-scale
pattern as compared with the Pacific. In particular, anomalously low
pressure is noted in the tropical Atlantic with a diminished Bermuda
HIGH and slightly increased pressures in higher latitudes. These lower
pressures in the Atlantic subtropical HIGH are usually accompanied by
low vertical wind shear in the main tropical cyclone development region
(south of 20N and east of the Lesser Antilles) with reduced trade winds
and more easterly upper-level flow.
The details of Eric's prediction scheme are better described with
charts and tables which would be difficult to reproduce in a plain text
document. Much more information on the August-only forecast scheme, and
its evolution since the first cut in 2000, may be found on the Colorado
State University website at the following links:
http://hurricane.atmos.colostate.edu/Forecasts/2000/august2000/>
http://hurricane.atmos.colostate.edu/Forecasts/2001/aug2001/>
http://hurricane.atmos.colostate.edu/Forecasts/2002/aug2002/>
http://hurricane.atmos.colostate.edu/Forecasts/2003/aug2003/>
The table below summarizes Eric's August-only forecasts from the
first one in 2000 up through this year's forecast:
FORECAST OF AUGUST TROPICAL CYCLONE ACTIVITY
Year NS H IH NSD HD IHD NTC
--------------------------------------------------------------
2000 3 2 1 14.25 8.25 1.25 33
2001 3 1 1 7.00 2.50 0.50 22
2002 4 1 0 10.00 4.00 0.00 18
2003 3 1 1 8.00 4.00 0.50 22
The following table summarizes actually observed August tropical
activity (2000-2002 based on official Best Track, 2003 based on
operational intensities):
OBSERVED AUGUST TROPICAL CYCLONE ACTIVITY
Year NS H IH NSD HD IHD NTC
--------------------------------------------------------------
2000 4 2 1 26.25 14.00 1.00 41
2001 3 0 0 10.25 0.00 0.00 9
2002 3 0 0 5.00 0.00 0.00 7
2003 3 1 1 6.00 2.25 1.25 23
As can be seen, the results for 2003 were exceptional, and the
initial forecast for August, 2002, was actually very good. The
NTC for that month was bumped up considerably by the anomalously
long-lived Hurricane Alberto. The forecasts for 2001 and 2002
were not so close, but were both on the correct side of climatology,
i.e., both called for below-normal activity, which was what was
observed. In fact, all four of the forecasts were on the correct
side of climatology--an important benchmark--especially considering
that two of the four seasons (2001 and 2003) had below-normal August
activity while the seasonal activity was well above normal.
Since 1950, in only 10 years has August failed to produce a
hurricane, and 2001-2002 is the first occurrence of two consecutive
hurricane-free Augusts. Also, in only two prior years (since 1950)
have there been as many as 3 NS in August with none reaching hurricane
intensity: 1984 and 1988.
(About three months ago Eric informed me that his paper was in the
review process pending publication in _Weather and Forecasting_. If
and when the paper is published, I shall include the particulars in
a future summary.)
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for July: 2 tropical depressions
2 hurricanes
Sources of Information
----------------------
Most of the information presented below was obtained from the
various tropical cyclone products issued by the Tropical Prediction
Center/National Hurricane Center (TPC/NHC) in Miami, Florida:
discussions, public advisories, forecast/advisories, tropical weather
outlooks, special tropical disturbance statements, etc. Some
additional information may have been gleaned from the monthly
summaries prepared by the hurricane specialists and available on
TPC/NHC's website. All references to sustained winds imply a
1-minute averaging period unless otherwise noted.
Atlantic Tropical Activity for July
-----------------------------------
July of 2003 turned out to be the most active month of July in six
years in the Atlantic basin. Two named tropical storms developed, but
both reached hurricane intensity, and one was rather long-lived for a
July cyclone, lasting almost 8 days as a tropical storm or hurricane.
Claudette moved on a rather long trajectory from the central Caribbean
where it developed until its final landfall on the middle Texas coast,
reaching hurricane intensity twice--first very briefly in the north-
western Caribbean, and then again shortly before making landfall in
Texas. Danny formed at a fairly high latitude from the northern
extension of a tropical wave and reached minimal hurricane status for
24 hours after it had recurved well to the south of Newfoundland.
The average Net Tropical Cyclone activity parameter (NTC) for July has
averaged 3.6% over the period 1950-2002. For this month the NTC was
14.2%--well above the average. (This includes 0.25 NSD contributed
by Tropical Storm Bill on 1 July.)
As the month of July opened, Bill was a weakening tropical storm
inland over Louisiana. Bill was downgraded to a tropical depression
at 0600 UTC on 1 July, and the remnants tracked northeastward across
the Southeast to the Mid-Atlantic coast, first as a tropical depression,
then as an extratropical LOW. During the early morning hours of 4 July,
three very small low-level circulations formed along a stationary front
extending between Bermuda and the Azores. None of the systems possessed
organized convection, and strong upper-level winds and cool SSTs
suppressed development. Nonetheless, the three little "neutercanes"
made an interesting sight in visible imagery on the 4th of July.
In addition to Claudette and Danny, two tropical depressions formed
but failed to reach tropical storm status. Tropical Depression 06 formed
on 19 July approximately 950 nm east of Barbados. Initially, the
depression was considered a good candidate for intensification, but as
it continued rapidly westward, environmental conditions became less
favorable (increasing shear and dry Saharan air) and the system was
unable to develop. A QuikScat pass on the morning of the 21st reported
winds near 45 kts, but a reconnaissance plane investigating the
depression that afternoon could not find a closed surface circulation, so
the system was downgraded to a tropical wave about 60 nm north-northwest
of Barbados. This tropical depression, like Claudette, was hampered in
its efforts to develop a closed surface circulation due to its rapid
translational speed. Whereas the pre-Claudette system persevered and
finally developed, this system was unable to do so in the face of other
adverse factors.
Tropical Depression 07 was a small circulation which formed on the
morning of 25 July only about 50 nm north-northeast of Cape Canaveral,
Florida. This depression's roots more than likely stemmed from the
tropical wave which had formerly been Tropical Depression 06. After
the demise of the earlier depression, the northern end of the wave
continued moving rapidly west-northwestward across the eastern Bahamas
and Cuba and moved into a small area of upper-level diffluence between
a couple of TUTT cells. On 24 July a large mesoscale convective system
blew up southeast of Miami and persisted for several hours, exhibiting a
circular shape and some evidence of symmetrical outflow. After the
system dissipated in the afternoon, a mesoscale vortex was clearly
evident in the cloud debris. This shallow system initially had no
associated deep convection as it began drifting northward in response to
the deep-layer mean steering.
By the morning of the 25th the system had developed enough deep
convection to warrant its being classified as a tropical depression.
The initial MSW was set at 25 kts, and an afternoon reconnaissance flight
confirmed that the winds likely did not exceed that value. The
depression was never forecast to reach tropical storm intensity, and that
prediction verified. Winds were estimated to have briefly reached 30 kts
at 26/0000 UTC over a very small area northeast of the center, based on
WSR-88D radar images which showed a banding feature becoming better
organized. By 0900 UTC on the 26th the depression's center had moved
inland about 40 km southwest of Savannah, Georgia. The weak cyclone
continued moving farther inland and had dissipated into a trough of
low pressure over central Georgia by the morning of the 27th. The peak
48-hour rainfall amounts reported in the HPC advisories were 45 mm and
43 mm from Charleston and Orangeburg, South Carolina, respectively.
The report on Hurricane Danny was written by Kevin Boyle, and the
portions of the report on Hurricane Claudette detailing meteorological
observations and damage and casualties were based largely upon infor-
mation sent to the author by John Wallace. A special thanks to John
and Kevin for their assistance.
HURRICANE CLAUDETTE
(TC-04)
8 - 17 July
---------------------------------------
A. Storm Origins
----------------
A tropical wave with an associated 1013-mb LOW moved off the west
African coast on 1 July. The wave was rather well-defined with some
low-level rotation, but convection weakened during the day due to a
fairly stable airmass over the Atlantic. The next day the wave
appeared even less impressive, becoming elongated southwest/northeast,
and the convection weakened even more. Over the next few days the
system moved westward with little convection--what convection remained
was located to the south along the ITCZ. By 5 July the wave had reached
the vicinity of 46W, and while still embedded in the ITCZ, had the
clearest signature of the waves currently being tracked. The Tropical
Weather Outlook issued by TPC/NHC at 1530 UTC mentioned the wave, but no
significant development was expected at the time.
The Tropical Weather Outlook at 0930 UTC on the 6th mentioned the
potential for some slow development over the next couple of days. The
wave was still embedded in the ITCZ, but a low-level cyclonic rotation
was noted near 10N. By 1800 UTC a 1008-mb LOW was located near 10.5N,
52.5W, or approximately 525 nm east of the Windward Islands. The cloud
pattern was well-organized with a curved band feature wrapping around
the northern semicircle, but deep convection was limited. A Special
Tropical Disturbance Statement was issued at 1745 UTC, indicating the
possibility of tropical cyclone development. Dry mid-level air to the
west was considered a possible inhibiting factor, but southerly inflow
of moist, unstable air to the east was a favorable factor.
By the morning of 7 July the disturbance was located about 260 nm
east of the Windwards, moving westward at 17 kts. The appearance was
somewhat ragged in satellite imagery with convection less concentrated
about the LLCC. There was no conclusive evidence that the system had
a closed surface circulation; nonetheless, the Tropical Weather Outlook
indicated that the islands were likely to see squalls to tropical storm
force as the wave passed through. A reconnaissance plane reached the
area around 1800 UTC and confirmed that there was yet no closed low-
level circulation. The lowest pressure found was 1009 mb, and the
wave axis had by this time already passed through the Lesser Antilles.
Wind gusts to 45 kts were reported on St. Lucia during the afternoon
as the wave passed over, moving at speeds of up to 20 kts into the
eastern Caribbean Sea.
Satellite imagery on the morning of the 8th indicated that the
convection had become more concentrated and organized and that cloud
tops had cooled. Visible imagery revealed increased banding as the
system continued racing westward at 26 kts. A reconnaissance plane
arrived in the area during the morning, but as the 1500 UTC advisory hour
approached, no closed surface circulation had yet been found. However,
winds on the poleward side of the system were above tropical storm
strength. Regular gale warnings were issued for portions of the Greater
Antilles likely to be affected by the system. Thus, this wave had
become one of those problematic, but fortunately rare, systems which
can produce winds exceeding gale force but without a closed circulation
at the surface. The system had the appearance in satellite imagery of
a tropical storm, and no doubt had a well-developed mid-level
circulation, but did not (or so was thought) meet the basic requirement
for a tropical cyclone of having a ground-relative low-level west wind.
Finally, after searching for nearly seven hours, the reconnaissance
plane at 1744 UTC found a south-southwest wind of 21 kts along with peak
flight-level winds (FLW) of 57 kts and a minimum pressure of 1006 mb.
Therefore, a Special Tropical Disturbance Statement was issued at 1810
UTC upgrading the system directly to Tropical Storm Claudette with
40-kt winds. (More discussion on the subject of these gale-bearing
tropical waves can be found at the end of this report in Section E.)
The first regular advisory on Claudette, at 08/2100 UTC, placed the
center of the new storm about 365 nm east-southeast of Kingston, Jamaica,
whizzing along to the west at 25 kts south of a strong subtropical ridge.
The MSW was increased slightly to 45 kts.
B. Storm History
----------------
Claudette's history over the next few days was characterized by
recurring cycles of intensification followed by weakening, followed by
another round of intensification, etc. The storm's rapid motion carried
it into close proximity to an upper-level LOW to the west which induced
unfavorable shear over the cyclone. Initially, the upper-level LOW was
forecast to weaken, and it was expected that Claudette would reach the
Yucatan Peninsula as a hurricane, but this scenario did not materialize.
The reconnaissance flight around 09/0000 UTC found a peak FLW of 72 kts
with a CP of 1000 mb, and a later mission into the storm around 0400 UTC
found a peak FLW of 85 kts northeast of the center. However, a
subsequent flight found only 55 kts, and also reported that the pressure
had risen to 1004 mb. Claudette's intensity was increased to 60 kts at
0900 UTC when the center was located about 175 nm south-southeast of
Kingston, but was lowered to 55 kts at 1500 UTC. Southwesterly shear had
caused the center to become intermittently exposed on the edge of the
convection.
At 09/2100 UTC Claudette was located about 220 nm south-southeast of
Grand Cayman and moving westward at a slightly slower speed of 21 kts.
The cyclone was producing bursts of convection with the LLCC moving
underneath the convection during the bursts, but subsequently becoming
exposed as the convection was sheared away. A reconnaissance plane
found peak FLW of 65 kts on two passes with the CP around 1001-1002 mb.
The MSW was decreased to 50 kts at 10/0300 UTC, and at 0900 UTC Claudette
was located 330 nm southeast of Cozumel, Mexico, moving west-
northwestward at 15 kts. An earlier reconnaissance flight had found a
peak FLW of 57 kts at 850 mb northeast of the center with a CP of 996 mb.
In the meantime a large, cold, distorted CDO-feature had developed over
the cyclone. Vertical shear was in the 20-25 kt range and was expected
to continue for the next several days.
By 1500 UTC Claudette's intensity had made a turnaround. A
reconnaissance plane at 1201 UTC reported a 10-nm diameter eye with a
CP of 988 mb and a peak FLW of 69 kts at 700 mb. The plane reported a
wind of 78 kts at 850 mb, but this was considered somewhat suspect.
The MSW was raised back to 60 kts at 1500 UTC, although on the second
pass through the storm the reconnaissance plane reported that the CP had
risen back to 993 mb. At 2100 UTC Tropical Storm Claudette was located
about 185 nm southeast of Cozumel and moving northwestward at 12 kts.
After its early morning intensification spurt, the storm had become less
organized and the winds were lowered back to 50 kts. The discussion
bulletin, however, noted that Claudette may have reached hurricane
intensity around 1530 UTC--a reconnaissance plane reported a peak FLW of
76 kts and an eyewall dropsonde indicated sustained winds of hurricane
force at the surface. Two hours later the plane found a fragmented wind-
field near the decayed eyewall. It should be noted that, based on infor-
mation in the monthly summary for July prepared by TPC/NHC, it has been
determined that Claudette did indeed briefly reach hurricane intensity
on the morning of 10 July.
The MSW was reduced to 45 kts at 0300 UTC on 11 July as Claudette
did not have a well-defined center. The storm was just north of Cozumel
at 0900 UTC, moving northwestward at 12 kts. The 0600 UTC reconnaissance
mission found a peak FLW of only 45 kts, but ship ELWX5 reported 50-kt
winds northeast of the center, so the MSW was raised back to 50 kts.
At 1500 UTC Claudette's center was over the northeastern tip of the
Yucatan Peninsula. The center was located to the southwest of a broadly
curved band of deep convection in which an earlier reconnaissance plane
had found winds to 55 kts. By 11/2100 UTC Claudette had moved out over
the Gulf of Mexico about 130 nm northwest of Cancun. The cyclone was
quite disorganized--the LLCC had become elongated east-northeast/
west-southwest, and several smaller cloud swirls could be seen rotating
around the mean center. The MSW was lowered back to 45 kts once more.
The 12th of July was an uneventful day in the life of Claudette. The
storm moved slowly northwestward to north-northwestward in the Gulf of
Mexico with little change in intensity, the MSW remaining at 45 kts all
day. At 2100 UTC the center was located approximately 350 nm east-
southeast of Brownsville, Texas. Peak winds at flight level reported
by reconnaissance missions were near 55 kts most of the day. The center
of the storm took a slight jog to the north, but then moved back to the
southwest early on the 13th, becoming more or less stationary about
270 nm east-southeast of Brownsville. During the morning of 13 July the
center was pulled into the deep convection once again, but this time
there was a response in the pressure field. The CP dropped as low as
994 mb before rising to 997 mb during the afternoon as the convection
was once more sheared away from the center. An early morning
reconnaissance flight found a peak FLW of 60 kts, so the MSW was upped
to 50 kts at 1500 UTC. A reconnaissance plane around midday found peak
winds of 69 kts at flight level.
Another reconnaissance plane during the evening hours found that the
LLCC had become well-established in all quadrants with the center
embedded in deep convection. A CP of 991 mb and a peak FLW of 68 kts
were measured; therefore, the MSW was increased to 55 kts at 14/0300 UTC.
The storm was still quasi-stationary at this time, but by 14/0900 UTC had
begun a slow northwesterly drift at 5 kts. The center was then fixed
about 270 nm east-southeast of Corpus Christi. A reconnaissance plane
around 1200 UTC reported winds at flight level of 65-70 kts, and the
crew noted that an open eyewall was present. At 2100 UTC Claudette's
center was located approximately 220 nm east of Corpus Christi, moving
north-northwestward at 6 kts. The MSW remained at 55 kts with the CP
having fallen slightly to 989 mb. The storm was still fighting shear
with the eye less defined than previously; however, several oil rigs
were reporting hurricane-force winds several hundred feet above the
surface.
The 15/0300 UTC advisory upped the winds to 60 kts--Claudette was
almost a hurricane. A reconnaissance plane had recently reported a
FLW of 77 kts in the northwest quadrant, and data from the NOAA Gulf-
stream jet indicated that shear was decreasing. At 15/0500 UTC an
intermediate advisory was issued upgrading Claudette to a hurricane.
The cyclone was then centered 150 nm east of Corpus Christi, moving
west at 7 kts. A reconnaissance flight around 0600 UTC recorded winds
of 84 kts in the northeast quadrant, and a dropsonde reported a pressure
of 982 mb, although the dropsonde missed the center of the eye.
Claudette's 25-nm eye was by now visible on coastal radars. At 1300 UTC
a NOAA buoy (WMO 42019), located a short distance south of the eye,
reported sustained winds to 47 kts (8-min avg), gusting to 60 kts.
At 1500 UTC Claudette's eye was closing in on the Texas coast, being
centered only about 17 nm east of Port O'Connor. A reconnaissance plane
had reported finding winds of 80-85 kts in the northeastern eyewall, and
the CP had fallen to 981 mb. WSR-88D data from Houston indicated winds
near 90 kts. Based on this, the MSW was upped to 70 kts at 1500 UTC,
and the advisory noted that winds could reach 75-80 kts before Claudette
began to weaken. A late-received eye dropsonde report indicated that the
pressure had fallen to 979 mb. The monthly report for July on TPC/NHC's
website indicates that Claudette's official intensity at landfall will
be increased to 80 kts. There was an unofficial report of sustained
winds to 82 kts, gusting to 90 kts, at Point Comfort, Texas.
Claudette continued moving inland across southern Texas and began to
slowly weaken. At 2100 UTC the cyclone was downgraded to a 60-kt
tropical storm located about 135 km southeast of San Antonio. By 0300
UTC on 16 July Claudette was located 110 km south-southwest of San
Antonio and NHC issued their final advisory, estimating the MSW still at
45 kts. With the primary threat from Claudette now inland flooding,
warning responsibility for the weakening cyclone was turned over to the
Hydrometeorological Prediction Center at Camp Springs, Maryland. The
first HPC advisory downgraded Claudette to a 25-kt depression near the
Rio Grande northwest of Laredo. The system maintained a fairly impres-
sive satellite signature for another day or so as it continued moving
generally up the Rio Grande valley. The final HPC advisory, issued at
0900 UTC on 17 July, placed the weakening circulation in northern Mexico
south of El Paso, Texas.
C. Meteorological Observations
------------------------------
(1) Wind Reports
----------------
As noted above, NOAA buoy (WMO 42019) reported an 8-min avg sustained
wind of 47 kts, gusting to 60 kts, while the eye was passing a short
distance to the north. The Port Aransas CMAN reported a MSW of 33 kts
(presumably a 1-min avg) with a gust to 38 kts at 15/2000 UTC. Victoria
reported a MSW of 45 kts with a peak gust of 59 kts at 1731 UTC, along
with a minimum SLP of 996 mb. Contact with this station, however, was
lost shortly thereafter for the duration of the storm.
A sustained wind of 68 kts, gusting to 83 kts, was recorded at a
Dow Chemical plant in Long Mott, Calhoun County, around 1700 UTC. Also,
an unofficial gust of 77 kts was recorded at a power plant in Matagorda
County. Wind gusts to 73 kts were recorded at Wadsworth and Port
Lavaca, where a tornado reportedly made a brief touchdown, causing
some damage. An unofficial gust of 70 kts was reported at Goliad,
Texas, about 30 km south-southwest of Victoria. Finally, as noted
above, there was an unofficial report of 82-kt sustained winds, gusting
to 90 kts, at Point Comfort.
(2) Rainfall Reports
--------------------
Rainfall totals from Claudette, as reported in advisories issued by
HPC, were rather light as far as tropical cyclone rainfall goes. Some
selected 6-hourly totals include:
Location Amount Date and Time Period
------------------------------------------------------------------
Corpus Christi 36 mm 16 July - 0000-0600 UTC
Cotulla 37 mm 16 July - 0600-1200 UTC
Angleton/Lake Jackson 39 mm 16 July - 1200-1800 UTC
Houston/Hull Field 33 mm 16 July - 1200-1800 UTC
A 12-hourly total of 26 mm was recorded at the Terrell County Air-
port between 16/1800 UTC and 17/0600 UTC. (Terrell County is located
along the Mexican border approximately 100-150 km northwest of the
city of Del Rio, Texas.)
D. Damage and Casualties
------------------------
The monthly summary for July on TPC/NHC's website indicates that
three persons lost their lives during Claudette, either directly or
indirectly. According to information sent to the author by John
Wallace, around 72,000 persons were without power during the storm.
About 70% of the businesses in Calhoun County sustained damage, and
75% of those in Port Lavaca were damaged. In Victoria County the
damage has been assessed at $10.6 million. The Victoria Airport
sustained damage of around $1.8 million while losses in the city of
Victoria have been estimated at $3.5 million, mostly to private
property. A very preliminary estimate places the total damage at
$17 million. This is likely to rise as it does not include flood
damage or any possibly significant damage to crops. Fifteen Texas
counties were declared federal disaster areas in the aftermath of
Hurricane Claudette.
In addition, the NHC report mentions that some minor damage was
incurred on the island of St. Lucia due to gusty winds and locally
heavy rainfall as the pre-Claudette wave passed through the Windwards.
E. Discussion
-------------
As noted earlier, the pre-Claudette tropical wave was one of those
problematic waves with tropical storm-force winds but without a
closed surface circulation--a basic requirement for a tropical cyclone.
The problem does not lie with nature in producing such systems, but
with our man-made classification and nomenclature system. By
definition (and I'm using U. S. terminology here), the weakest type of
tropical cyclone is a tropical depression, which must have maximum
sustained winds less than 34 kts. And for decades the U. S. public
has been informed that a tropical disturbance (or tropical wave) is
weaker than a tropical depression. As an example, the final public
advisory on Tropical Depression 06, issued at 2100 UTC on 21 July,
contains as the header line: "depression weakens to a tropical wave."
In June I sent out a tropical cyclone survey to a few dozen persons.
The survey treated several tropical cyclone classification issues, and
one of those was this issue of how to best handle these strong, rapidly-
moving tropical waves with tropical storm-force winds. A summary of
the responses will appear in a monthly feature in a few months, so the
comments here will be brief. One distinction which should be made is
that between simply gale-bearing tropical waves with little evidence of
a storm-relative circulation, and those (such as pre-Claudette) which
appear to have a definite circulation relative to the "center", but
which doesn't extend down to the surface sufficiently to produce
westerly winds relative to a ground-based observer on the equatorward
side of the wave.
The responses to the above-mentioned survey tended to be in favor
of "bending" the rules for tropical storm classification in regard to
such systems, although there were some voices adamantly opposed to
this. Most of those in favor of naming such systems as tropical storms
base this on the argument that whenever a system is named, the attention
of the public and mariners jumps up by an order of magnitude (something
which I've found to be true in my experience). On the other hand,
there are those who point out that weather systems other than tropical
storms can produce gale-force winds in the deep tropics and that
ordinary gale warnings should be sufficient.
The following quote from an e-mail written by Kenneth J. Schaudt
of Marathon Oil Company illustrates how the attention of the public
and other concerned parties spikes up when a tropical storm is named:
"Much of the United States' natural gas is produced in the Gulf of
Mexico. Since the threat of tropical storms may shut down production
briefly, the market for natural gas responds to the perceived threats.
On the 8th (of July) at 1806 UTC, the Special Tropical Disturbance
Statement declaring Tropical Storm Claudette hit the wire. Within
three minutes, the price of natural gas had jumped 10 cents."
As I've already stated, I'll wait until I prepare a monthly feature
on this topic before going into more details. If anyone who did not
receive the aforementioned survey would like to state his/her opinion
on this topic, please e-mail your comments to me and I'll include them
in the future monthly feature.
(Report written by Gary Padgett with contributions by John Wallace)
HURRICANE DANNY
(TC-05)
16 - 23 July
-----------------------------------
A. Storm Origins
----------------
The origins of Hurricane Danny stemmed from the northern part of a
rather large tropical wave that left the African coast on 10 July. NHC
included this large tropical wave (devoid of thunderstorm activity) in
their Tropical Weather Outlook as early as 13 July (issued at 2130 UTC),
stating that there was some potential for development over the next few
days as the system moved westward over warmer waters. The wave moved
uneventfully westward across the tropical Atlantic during the 14th. A
NCEP/MPC 0000 UTC preliminary surface analysis chart on 15 July showed
a trough splitting from the northern portion of the wave, which, by that
time, lay along 49W. An increase in shower/thunderstorm production was
also noted in satellite images. By early on the 16th a LOW had formed
in association with the area of disturbed weather, which had drifted
northwest to a position located roughly 700 nm east-southeast of Bermuda.
Satellite images depicted the weak LLCC located southwest of the main
area of deep convection induced by southwesterly vertical shear.
However, they also revealed an organizing system that was moving north-
westward at 17 kts toward a progressively more favourable upper-level
environment. Based on satellite images and ship reports, NHC issued the
first advisory on Tropical Depression Five at 1500 UTC on 16 July,
located near 31.5N, 54.5W, or about 525 nm east of Bermuda. The initial
intensity was set at 25 kts and some additional strengthening was fore-
cast for the following two to three days as the system traversed the
warm Atlantic waters that lay ahead of the depression.
B. Storm History
----------------
Overall organization of Tropical Depression Five continued to improve
with deep central core convection developing and banding evident in the
northern semicircle. Outflow was good to the northwest and excellent to
the northeast. The only negative influence was the presence of south-
easterly shear which tilted the vertical profile of the storm slightly
towards the northwest. By 17/0300 UTC satellite CI estimates had reached
35 kts and the depression was upgraded to Tropical Storm Danny when
located approximately 475 nm east of Bermuda. This was increased to
45 kts six hours later based on the appearance of a 10-nm diameter eye
feature as indicated by a 17/0339 UTC TRMM overhead pass. The next
six-hour increment saw another 10 kts added, bringing the MSW up to
55 kts. After that, intensification eased off but the cyclone remained
impressive enough with good outflow and two main hooking bands. Danny
was moving on a northward path at around 10 kts at 17/2100 UTC.
A little more strengthening was expected before Danny ran out of warm
water, but judging by 18/0000 UTC satellite imagery, it appeared that the
cyclone was not going to reach hurricane strength. The images showed
that banding was minimal, and most of the convection was limited to a
burst near the centre caused by westerly shearing. Additionally, Dvorak
numbers were falling. Visible satellite images and microwave data at
18/1500 UTC, however, contradicted this fact and showed that Danny (now
moving northeastward at 14 kts) was nearing hurricane strength. Well-
defined curved bands were noted wrapping around a small CDO with
excellent outflow aloft, although convective tops were not very cold.
Satellite CI estimates from TAFB, AFWA, and SAB had increased to 60 kts
by this time. Just as Danny had begun to trek northeastward over colder
waters at 18/2100 UTC, the MSW was raised to 65 kts based on satellite
microwave data showing a definite eye. Danny had become the second
hurricane of the 2003 season while located about 450 nm south of
St. John's, Newfoundland.
Hurricane Danny held its MSW of 65 kts for much of the 19th as it
moved on a northeasterly heading at 16 kts over increasingly cooler
waters. (NOTE: Normally a 65-kt Atlantic hurricane has a CP near
987 mb. However, because Danny was located in a high surface pressure
environment all its life, the CP was likely much higher than 987 mb.
Unfortunately, there was no data to determine the exact pressure, so
1005 mb was used as the minimum CP with a greater than normal uncertainty
about the value.) Weakening began at 19/2100 UTC as the MSW dropped
below hurricane intensity. Danny had curved onto an easterly path by
this time, and the main emphasis was on what could happen to the
tropical cyclone in the days to come.
Danny's track was completely influenced by a large, semi-permanent
subtropical HIGH. During its life it had travelled in a huge clockwise
loop around this HIGH and was forecast to sink to the south on the
eastern side of the anticyclone as a remnant LOW, with the possibility
of regeneration over increasingly warmer waters. Its track was somewhat
reminiscent of the long-lived Hurricane Alberto in August, 2000.
However, Danny was not destined to emulate the long, meandering exploits
of Alberto nor that of Hurricane Kyle (2002).
A dramatic deterioration occurred early on the 20th as the deep
convection was ripped off the LLCC by northwesterly vertical shear,
leaving the centre completely exposed. Even though CI estimates were
between 55-65 kts from all three agencies, the MSW was dropped to 50 kts
at 20/0300 UTC. For the rest of the 20th it was a case of winding the
storm down: first to 45 kts at 20/0900 UTC (based on QuikScat data and
a buoy MSL pressure report of 1008.0 mb at 0600 UTC), followed by a
further drop to 35 kts six hours later. The weakening tropical storm
began to move more south of east around this time. The MSW fell below
the tropical storm threshold of 34 kts at 20/2100 UTC, which was the time
of the final advisory issued by NHC. At the time Danny was centred
approximately 360 nm west-northwest of Flores in the Azores. Little
convection was associated with Danny and it was far from the exposed
LLCC.
NHC continued to monitor Danny's remnants in their Tropical Weather
Outlooks until 24 July. The remnant LOW was tracked south-southeastward,
then southward during the 21st before turning southwest the next day.
The LOW was centred about 420 nm southwest of the northern Azores at
22/1530 UTC. Associated convective activity was sporadic during this
period. Having almost completed a full circuit around the HIGH, Danny
finally gave up the ghost when it was last mentioned in the 24/2130 UTC
Tropical Weather Outlook. Its final reference point was roughly 435 nm
west-southwest of Flores in the Azores.
C. Damage and Casualties
------------------------
Hurricane Danny spent its entire life over the subtropical Atlantic
Ocean. No damage or casualties have been reported.
(Report written by Kevin Boyle)
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for July: 3 tropical storms
Sources of Information
----------------------
Most of the information presented below was obtained from the
various tropical cyclone products issued by the Tropical Prediction
Center/National Hurricane Center (TPC/NHC) in Miami, Florida (or the
Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii, for
locations west of longitude 140W): discussions, public advisories,
forecast/advisories, tropical weather outlooks, special tropical
disturbance statements, etc. Some additional information may have
been gleaned from the monthly summaries prepared by the hurricane
specialists and available on TPC/NHC's website. All references to
sustained winds imply a 1-minute averaging period unless otherwise
noted.
Northeast Pacific Tropical Activity for July
--------------------------------------------
Over the period 1971-2002 the month of July in the Northeast Pacific
basin has averaged about 4 named storms, 2 hurricanes and 1 intense (or
major) hurricane, and has produced an average NTC of 23.5%. July of 2003
turned out to be one of the most inactive Julys on record. Three rather
short-lived tropical storms developed, and none reached hurricane
intensity. The total NTC of 4.2% was the lowest since 1977. Dolores
was a tropical storm for only 12 hours, while Enrique and Felicia were
both at tropical storm intensity for about two days each. None of the
cyclones affected the Mexican coastline, nor did any enter the Central
Pacific (west of 140W).
TROPICAL STORM DOLORES
(TC-04E)
6 - 8 July
------------------------------------------
The precursor of Tropical Storm Dolores was a tropical wave which
moved off the African coast on 20 June and moved westward across the
Atlantic with little associated convection. On 25 June the system
entered the eastern Caribbean Sea, bringing widely scattered showers
and thunderstorms to the Windward Islands. The environment was hostile
for tropical cyclogenesis with an upper-level trough and moderate
subsidence over the region. The tropical wave entered the Eastern
Pacific on 30 June, and by 1 July an area of disturbed weather had formed
about 435 nm south-southwest of Acapulco. A Tropical Weather Outlook
issued by TPC/NHC at 01/2300 UTC noted that upper-level winds were
marginally favorable for development. The disturbance moved westward
over the next few days, very gradually increasing in organization.
By the morning of 5 July the system had reached a point approximately
700 nm south-southwest of Cabo San Lucas, and the 1700 UTC Tropical
Weather Outlook indicated that a tropical depression could form during
the afternoon or night.
By 0600 on 6 July an impressive CDO feature had developed. With
Dvorak T-numbers of 2.5/2.0/2.0 from TAFB, SAB, and AFWA, respectively,
advisories were initiated on Tropical Depression 04E at 06/0900 UTC,
located roughly 400 nm southwest of Socorro Island. The depression
moved on a general northwesterly track, reaching tropical storm intensity
around 1800 UTC when located about 450 nm west-southwest of Socorro.
The system was upgraded to Tropical Storm Dolores with 35-kt winds at
2100 UTC. From the outset Dolores did not have great prospects for a
long life--it was battling northeasterly shear and was forecast to move
over sub-25 C SSTs after about 48 hours. After only twelve hours as a
tropical storm, Dolores was downgraded to a depression at 0900 UTC on
7 July. The LLCC was exposed and displaced to the east-northeast of
decreasing deep convection. By 1500 UTC the weakening cyclone was over
sub-25 C water and devoid of any deep convection. A 07/1358 UTC Quik-
Scat pass indicated winds of only 20-25 kts.
The final advisory was issued at 0300 UTC on 8 July, placing the
center approximately 750 nm west-southwest of Cabo San Lucas. A few
cells of deep convection had redeveloped to the southwest of the LLCC,
but Dolores was in the process of degenerating into a remnant LOW.
No damage or casualties are known to have resulted from Tropical
Storm Dolores.
(Report written by Gary Padgett)
TROPICAL STORM ENRIQUE
(TC-05E)
10 - 13 July
------------------------------------------
Like its predecessor Tropical Storm Dolores, Tropical Storm Enrique's
origins can be traced back to a tropical wave which emanated out of the
African continent. On 25 June a tropical wave moved off the west coast
of Africa and embarked on its trek across the Atlantic. The wave had
little associated convection and was often difficult to keep track of in
satellite imagery. By 28 June the wave had developed an associated
1012-mb LOW near 7N, and was improving in organization with the formation
of curved banding features and plenty of convection. The LOW was rather
far south for tropical cyclone formation, but QuikScat data confirmed the
existence of a surface circulation. Conditions were marginally
favorable for some development, but this did not materialize. On 30 June
visible satellite imagery indicated a small-scale LLCC embedded in the
ITCZ, but convection was virtually non-existent.
The wave continued westward across the southern Caribbean/northern
South America area and had entered the Eastern Pacific by 6 July. At
07/0000 UTC a broad, diffuse cyclonic circulation was located southwest
of Costa Rica but with no significant convection. At 0600 UTC the
system was repositioned westward to 89W based on a well-defined cloud
pattern and low-level turning in satellite imagery. A Tropical Weather
Outlook issued by TPC/NHC at 1100 UTC indicated that an area of disturbed
weather about 220 nm south of the Guatemalan coast had some potential for
development over the next few days. By the afternoon of 8 July the
disturbance was located about 325 nm south of Acapulco. Ship H3KF
reported winds of 25 kts and a SLP of 1009.5 mb at 09/0000 UTC in the
vicinity of the disturbance. By the morning of 9 July the system had
reached a location about 250 nm southwest of Acapulco, and the 1700 UTC
Tropical Weather Outlook indicated that it had become better organized
with environmental conditions favoring further development.
Visible satellite imagery on the morning of 10 July revealed a well-
defined circulation, although it was exposed and well-removed from the
deep convection. Nonetheless, there was enough organization to warrant
upgrading to Tropical Depression 05E. The first advisory at 10/1500 UTC
placed the center roughly 350 nm south-southwest of Manzanillo, Mexico.
The depression was battling strong northeasterly shear, and was initially
forecast not to strengthen above 40 kts before encountering cooler SSTs.
Some consolidation of the cyclone was noted during the evening as a few
bursts of deep convection fired off near the LLCC and convective banding
observed earlier well-removed from the center diminished.
During the night some rather intense convection developed over the
LLCC. A SSM/I pass indicated that the LLCC was embedded at least 30 nm
within the eastern portion of some -70 C cloud tops. Based on a
consensus of 30 kts satellite intensity estimates, the rapidly improving
convective pattern, and the new center location, the cyclone was upgraded
to Tropical Storm Enrique at 0900 UTC on 11 July, located approximately
500 nm south of Cabo San Lucas. As Enrique moved northwestward the
shear lessened and the storm became better organized. Winds reached an
estimated peak of 55 kts at 0300 UTC on 12 July with the CP estimated at
994 mb. Data T-numbers were 55 kts from all three satellite agencies
at the time. Enrique was forecast to briefly reach minimal hurricane
intensity, but this did not materialize.
Twelve hours later Enrique still maintained an impressive convective
pattern with cloud tops to -80 C near the center. The MSW was still
estimated at 55 kts, but a TRMM overpass at 12/0802 UTC showed no eye
and a partly-exposed center west of the main convective bands. Cirrus
outflow was good in all directions, but there were hints in satellite
imagery that weak westerly flow was undercutting the outflow. Shortly
thereafter, Enrique moved into colder waters and began to steadily
weaken. By 13/0900 UTC the LLCC was rapidly separating from the mid/
upper-level circulation with the deep convection displaced well to the
northeast. First visible images on the 13th showed a LLCC displaced
about 150 nm southwest of diminishing deep convection. Enrique was
reduced to depression status at 1500 UTC, and the final advisory was
issued at 2100 UTC, locating the convection-free low-level cloud swirl
about 650 nm west-southwest of Cabo San Lucas.
No damage or casualties are known to have resulted from Tropical
Storm Enrique.
(Report written by Gary Padgett)
TROPICAL STORM FELICIA
(TC-06E)
18 - 23 July
------------------------------------------
Unlike Enrique and Dolores, the progenitor of Tropical Storm Felicia
cannot be traced with certainty to a tropical wave of African origin.
On 13 July a low-pressure area was located south of El Salvador with
scattered moderate convection within 150 nm of the center. The LOW
had moved across Costa Rica the previous night, so it had obviously
moved from the Caribbean. Whether or not it was related to a tropical
wave is unknown to the author. By mid-day on 14 July the LOW was
centered south of the Gulf of Tehuantepec and was better organized,
although most of the deep convection was located west of the LLCC. The
system passed about 280 nm south of Acapulco on 15 July, and was better
organized by the morning of the 16th, but the upper-level environment
was only marginally favorable for development. By 0500 UTC on 17 July
the LOW was located about 390 nm south of Manzanillo, Mexico, and the
upper-level winds were becoming somewhat less hostile for tropical
cyclogenesis.
The first advisory on Tropical Depression 06E was issued at 0300 UTC
on 18 July. Dvorak classifications from the three agencies were all
T2.0, so advisories were initiated. TD-06E was then located roughly
325 nm south-southwest of Manzanillo, Mexico. Like its predecessors,
the depression developed under substantial easterly shear, although this
was forecast to lessen with time. Satellite intensity estimates had
reached 35 kts six hours later based on a small, cold CDO feature, but
the forecaster was reluctant to upgrade the system based on nighttime
infrared imagery. TD-06E was upgraded to Tropical Storm Felicia with
45-kt winds on the third advisory at 1500 UTC on 18 July. The storm was
located approximately 500 nm south of Cabo San Lucas, moving westward
at 16 kts. This was very near the same locale where Enrique had reached
tropical storm intensity one week earlier.
The 18/1500 UTC advisory had forecast Felicia to briefly reach
minimal hurricane intensity, but this was not to be. Shortly after the
1500 UTC advisory was released, a SSM/I pass over the cyclone indicated
that the center was located to the northeast of the convection and not
embedded as previously estimated. The initial position was adjusted
slightly to the north and the winds were decreased to 40 kts. The new
forecast (at 2100 UTC) called for Felicia to remain at 40 kts for about
24 hours and then begin to weaken. This was exactly what happened.
Felicia's center remained partly-exposed on the north side of the deeper
convection as it moved westward at around 15 kts. By 2100 UTC on the
19th the center had become exposed to the north of limited deep
convection and the intensity was reduced to 35 kts.
Satellite intensity estimates at 20/0000 UTC ranged from 25 to 35 kts,
but considering the fairly rapid translation speed (16 kts), the MSW
was retained at 35 kts. Felicia was still generating limited deep
convection on the south side, and the environment was still marginally
favorable for intensification with low shear and SSTs around 26-27 C,
but the surrounding air was rather dry. A QuikScat pass at 20/0200 UTC
showed only a few rain-flagged 35-kt vectors in the convection, so the
system was downgraded to a depression at 0900 UTC, located about 775 nm
southwest of Cabo San Lucas. Felicia continued westward for the next
three days in advisory status, mainly because of sporadic bursts of
convection and an occasional T2.5 rating from a satellite analyst. By
0900 UTC on 22 July there was no significant convection within 60 nm of
the fully-exposed circulation center, so the MSW was decreased to 25 kts.
QuikScat data also supported this intensity. The weakening cyclone
still produced some isolated convection for another 24 hours, but by
0900 UTC on the 23rd it had been convection-free for six hours, and the
mid/upper-level circulation had been sheared off about 200 nm to the
east. With upper-level westerly shear forecast to increase to 50 kts
within 24 to 48 hours, the final advisory on Felicia was issued. The
dissipating center was located approximately 1500 nm west-southwest of
Cabo San Lucas, or about 1100 nm east-southeast of Hilo, Hawaii.
There are no reports of damage or casualties associated with Tropical
Storm Felicia.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for July: 2 tropical depressions **
1 typhoon ++
1 super typhoon
** - one classified as a tropical depression by PAGASA--the other by
PAGASA and JMA
++ - classified as a typhoon by JTWC only
Sources of Information
----------------------
Most of the information presented below is based upon tropical
cyclone warnings and significant tropical weather outlooks issued
by the Joint Typhoon Warning Center of the U. S. Air Force and
Navy (JTWC), located at Pearl Harbor, Hawaii. In the companion
tropical cyclone tracks file, I normally annotate track coordinates
from some of the various Asian warning centers when their center
positions differ from JTWC's by usually 40-50 nm or more. All
references to sustained winds imply a 1-minute averaging period
unless otherwise noted.
Michael V. Padua of Naga City in the Philippines, owner of the
Typhoon 2000 website, normally sends me cyclone tracks based upon
warnings issued by the Japanese Meteorological Agency (JMA) and the
Philippines' Atmospheric, Geophysical & Astronomical Services
Administration (PAGASA). Also, Huang Chunliang of Fuzhou City, China,
sends me each month tracks obtained from warnings issued by the
National Meteorological Center of China (NMCC), the Central Weather
Bureau of Taiwan (CWBT) and the Hong Kong Observatory (HKO). A very
special thanks to Michael and Chunliang for the assistance they so
reliably provide.
In the title line for each storm I have referenced all the cyclone
names/numbers I have available: JTWC's depression number, the
JMA-assigned name (if any), JMA's tropical storm numeric designator,
and PAGASA's name for systems forming in or passing through their
area of warning responsibility.
Northwest Pacific Tropical Activity for July
--------------------------------------------
July activity was close to normal in the Northwest Pacific basin.
According to information from JTWC's website, the average number of
tropical cyclones during the 1959-2001 period was 4.7, but this number
includes tropical depressions plus those reaching tropical storm
intensity. The average number of typhoons was listed as 2.7 for the
period 1960-2001. July of 2003 produced either 2, 3 or 4 tropical
depressions, depending on which agency's classifications one follows.
JTWC issued warnings on only two cyclones, both of which reached typhoon
status, although JTWC was the only agency to upgrade Koni to a typhoon.
PAGASA classified and named two other systems as depressions--one of
these was treated briefly as a tropical depression by JMA also.
Tropical Storm Koni (named Gilas by PAGASA) moved across the central
Philippines around mid-month. After reaching the South China Sea the
cyclone turned to a northwesterly heading and headed for Hainan Dao
while intensifying to a minimal typhoon (per JTWC). Koni then turned
due westward, crossed Hainan Dao and the Gulf of Tonkin before making
a final landfall in Vietnam. Much more potent and deadly was Super
Typhoon Imbudo (known as Harurot in the Philippines). Imbudo followed
the classic west-northwestward "straight-shooter" track from deep in the
Philippine Sea across northern Luzon and into southern China. Imbudo
developed into the year's second super typhoon with 130-kt peak winds
(per JTWC). The storm was deadly and destructive to both the Philippines
and China.
A weak circulation in the central South China Sea on 9-10 July was
classified as Tropical Depression Falcon by PAGASA. JMA also treated
this system as a tropical depression with both agencies estimating 30-kt
winds at 0600 and 1200 UTC on the 9th. Also, PAGASA designated another
weak system on 30 July as Tropical Depression Ineng. Ineng was located
well to the east of Mindanao, and the peak MSW was estimated by PAGASA
at only 25 kts. To the author's knowledge, none of the other warning
centers treated Falcon or Ineng as tropical depressions.
The reports on Typhoons Koni and Imbudo were written by Kevin Boyle,
and contain much information supplied by Huang Chunliang. A special
thanks to Kevin and Chunliang for their assistance.
TYPHOON KONI
(TC-08W / STS 0308 / GILAS)
15 - 22 July
-----------------------------------------------
Koni: contributed by the Republic of Korea (South Korea), is the Korean
word for 'swan', a bird which migrates from Siberia each year to
spend the winter in Korea. Since a male and female swan mate for
life, the swan is regarded as a symbol of loyalty.
Gilas: PAGASA name, means 'amazing'
A. Storm Origins
----------------------
During the second week of July the monsoon trough became very active,
spawning two disturbances, the first of which was mentioned in the 1500
UTC 12 July STWO issued by JTWC. The associated area of deep convection
was situated near 5.9N, 144.1E, or approximately 440 nm south of Guam.
Animated infrared satellite imagery revealed an area of cycling deep
convection whilst upper-level wind shear conditions were ideal for
further development with moderate diffluence aloft. However, development
potential for the next 24 hours was assessed by JTWC to be poor. This
was upgraded to fair at 13/0600 UTC based on observations made by multi-
spectral satellite animations which showed cycling deep convection
organizing around a weak LLCC. However, the convection associated with
the possible LLCC subsequently decreased significantly such that the
potential for development was once again downgraded to poor status.
The disturbance changed little through the 14th, although late in the
day animated multi-spectral satellite imagery revealed that cycling deep
convection was re-organizing with spiral bands and low-level cloud lines
becoming evident. This observation prompted JTWC to issue a TCFA at
15/0200 UTC which located the disturbance near 10.9N, 135.2E, or 125 nm
north of Palau. The STWO issued at 15/0600 UTC stated that recent
QuikScat and synoptic data were locating the position of the surface
circulation further south than previously thought. By this time, the
system had crossed 135E into PAGASA's AOR and was named Gilas by that
agency, who considered it as a 30-kt tropical depression (10-min avg).
Tropical Depression 08W finally made its debut at 15/1200 UTC, located
180 nm northwest of Palau (or 9.9N, 132.6E), moving westward at 11 kts.
The MSW was estimated to be 25 kts at this stage. Tropical Depression
08W/Gilas continued westward while slowly strengthening and
consolidating. By 16/0600 UTC the MSW had reached minimal tropical
storm intensity. (JMA began including the depression in their High Seas
bulletins at 16/0000 UTC, fixing the system near 9.2N, 130.5E.).
B. Track and Intensity History
------------------------------
By 0000 UTC on 17 July Tropical Storm 08W/Gilas had moved steadily
westward with the partially-exposed LLCC located along the east coast
of Samar. The MSW had, by this time increased to 45 kts, but the system
had a more hostile environment to work with: easterly wind shear, land
influences, and loss of an outflow pattern that had been provided by a
TUTT cell located to the northeast. CIMSS Shear Products showed that
the easterly shearing conditions were likely to persist even as Gilas
cleared the Philippines, but the shear was considered light enough for
some strengthening to occur. By 17/1200 UTC TS-08W/Gilas had crossed
the bulk of the Philippines with the centre located over Panay Island.
The system had weakened slightly to 40 kts during its transit across
land, but the MSW slowly began to trend upward as the cyclone moved into
the South China Sea at 1800 UTC (after the centre had clipped northern
Palawan). Multi-spectral and microwave imagery indicated an increase in
deep convection at this time. A shortwave trough moving off the Chinese
coast created a weakness in the subtropical ridge during the 18th, and
in response to this the storm (now named Koni following JMA's upgrade to
tropical storm status at 18/0600 UTC) began a northwesterly jaunt which
was to last through the 19th, 20th, and into the 21st. (HKO and NMCC
initiated bulletins at 17/0600 UTC and 18/0600 UTC, respectively,
although NMCC had issued two irregular bulletins on the system at
17/0000 UTC and 18/0000 UTC. Both NMCC and HKO upgraded the system to
tropical storm intensity at 18/0600 UTC.)
At 19/0000 UTC Tropical Storm Koni was centred approximately 225 nm
west-southwest of Manila (13.7N, 117.2E), well away from the interfering
influence of the Philippines. However, intensification was slow due to
the effects of northeasterly shearing conditions until 1800 UTC, when
Koni took advantage of a lull in the shear and strengthened into a 65-kt
minimal typhoon at 20/0000 UTC. (At 19/1800 UTC PAGASA ceased issuing
bulletins as Koni/Gilas had moved out of their AOR, allowing the
agency to fully concentrate on the rapidly developing Super Typhoon
Imbudo/Harurot.) Koni's movement at this time was still toward the
northwest at around 10 kts, the centre fixed approximately 370 nm west-
northwest of Manila and roughly halfway to its impending landfall on
Hainan Dao. Although Koni was expected to strengthen some more in a
favourable environment, the MSW of 65 kts was to be its maximum
intensity. However, this intensity was maintained through the 20th and
21st as the cyclone continued on a northwesterly heading, then westward
toward the island of Hainan. A 20/1309 UTC GHz microwave pass revealed
a partial symmetrical eye. (Note: None of the Asian TCWCs upgraded
Koni to typhoon status. Peak intensities include: JMA 60 kts with a CP
of 975 mb, PAGASA 55 kts, NMCC 60 kts and HKO 55 kts. All the MSW
estimates represent a 10-min avg).
At 0000 UTC on the 21st Typhoon Koni was centred approximately 90 nm
east-southeast of Hainan Dao, moving toward the northwest at 8 kts.
Upper-level northeasterly shear was stripping away the convection in the
northern quadrants of the storm, as seen in water vapor imagery.
Animated infrared satellite imagery and synoptic observations indicated
that Typhoon Koni made landfall approximately 30 nm south-southwest of
Qionghai on the island of Hainan at approximately 21/1200 UTC. By this
time Koni had taken a westerly track which was to persist for the rest
of its existence. After its transit across Hainan Dao the cyclone
continued westward across the Gulf of Tonkin and began to weaken as it
approached the Vietnamese coast. The MSW fell below typhoon strength
and had dropped to 55 kts by the time Koni crossed into northern Vietnam
south of Hanoi at approximately 22/0800 UTC. The storm rapidly
deteriorated as it moved further inland, and was dissipating as a
significant tropical cyclone over land by 22/1800 UTC--the time of the
final warning issued by JTWC. The system was tracking westward over
Laos on this last advisory with the MSW estimated at 35 kts. HKO issued
their final warning at 22/0900 UTC (AOR limit) while both JMA and NMCC
ended their coverage six hours later.
C. Meteorological Observations
------------------------------
Based on NMCC warnings, Tropical Storm Koni made landfall near
Beipo Town, Wanning City, Hainan Province around 21/1035 UTC with the
MSW estimated at 41 kts and a CP of 980 hPa. Gusts of Beaufort Force
8-10 were widely recorded on Hainan Dao, and Dofang City reported a
gust of Beaufort Force 11.
Following are a few rainfall totals from Chinese stations sent by
Huang Chunliang:
Station Province Rainfall (mm) Reporting Period (UTC)
-----------------------------------------------------------------------
Lingshui Hainan 177 21/0000 - 22/0000
Lingshui Hainan 179.5 20/0000 - 22/0600
Sanya Hainan 112 21/0000 - 22/0000
Wuzhi Mt. Hainan 188.8 20/0000 - 22/0800
C. Damage and Casualties
------------------------
In Hainan Province, China, some 249,000 residents in 122 towns of
15 cities/counties were affected by the storm. The number of collapsed
houses was approximately 1400 in the province. Direct economic losses
were estimated at 140,270 million yuan. The "swan" did cause some
damage to Hainan, especially in the cities of Wanning, Baoting and
Sanya. However, thanks to the storm, the drought at that time in the
province was also eased. No casualties were reported in association
with Severe Tropical Storm Koni.
According to press reports, two people were killed and 18 injured as
Tropical Storm Koni lashed northern Vietnam, uprooting trees, felling
power lines and destroying more than 1000 houses. There were no reports
of damage or casualties in the Philippines.
The HKO report on Severe Tropical Storm Koni can be accessed at the
following URL:
http://www.weather.gov.hk/informtc/koni/koni.htm>
(Report written by Kevin Boyle with important contributions by
Huang Chunliang)
SUPER TYPHOON IMBUDO
(TC-09W / TY 0307 / HARUROT)
15 - 25 July
------------------------------------------------
Imbudo: contributed by the Philippines, means 'funnel' or 'downspout'
Harurot: PAGASA name, means 'very fast' or 'top speed'
A. Storm Origins
----------------------
An area of convection developed and persisted approximately 100 nm
east-southeast of Chuuk and was first included in the 0600 UTC 14 July
STWO. Animated multi-spectral satellite imagery revealed disorganized
deep convection near a possible weak LLCC. Upper-level analysis
indicated moderate diffluence aloft and weak vertical wind shear over
the area. The potential for the development of a significant tropical
cyclone within the next 24 hours was considered poor. This was upgraded
to fair at 15/0230 UTC after the system had become better organized with
low-level cloud lines evident at the surface as seen in multi-spectral
satellite animation. A TCFA was issued at 16/0600 UTC on the basis of
continued organization. Upper-air analysis at this time revealed that
an upper-level LOW to the northwest was aiding development by providing
an ideal poleward outflow pattern.
The first warning was issued on Tropical Depression 09W at 16/1800
UTC with the system located 360 nm east-southeast of Yap Island
(near 7.0N, 143.6E), and the initial movement was toward the north-
northwest at 11 kts. This heading swung to the west-northwest during
the 17th as the cyclone's broad circulation continued its organization
phase. The depression was named Imbudo at 17/0600 UTC when JMA upgraded
it to tropical storm intensity. At the same time NMCC issued the first
warning after issuing an irregular bulletin at 17/0000 UTC. Tropical
Depression Imbudo was soon upgraded by JTWC six hours later with the MSW
estimated at 40 kts. Recent microwave and animated infrared imagery
indicated that banding features were developing and wrapping in from
the north of the system. The centre of Imbudo had moved west-
northwestward to a position 125 nm east-southeast of Yap Island by the
time of JTWC's upgrade.
B. Storm History
----------------
By 0000 UTC on 18 July Tropical Storm Imbudo was passing 18 nm north
of Yap Island while moving west-northwestward with a MSW of 50 kts.
Strengthening continued as the day wore on--the forward motion slowed to
around 5 to 7 kts and the heading turned westerly. This was forecast to
persist for the near term, but a passing longwave trough was expected to
dig into the mid-level ridge, forcing the storm northwestward for awhile.
An upper-level LOW situated to the northeast of the tropical cyclone, as
seen on UW-CIMSS 200-mb data, provided excellent diffluence, allowing
Imbudo to strengthen into a 65-kt typhoon by 1800 UTC that same day.
This signalled the beginning of a rapid intensification phase which
brought Imbudo up to 75 kts by 19/1200 UTC. Satellite CI estimates had
reached 90 kts by 20/0000 UTC, and a 19/2044 UTC TRMM pass revealed a
15-nm irregular eye.
Only twelve hours more were required for Imbudo to attain super
typhoon status of 130 kts--its peak intensity. (JMA's peak of 85 kts
10-min avg MSW with a CP of 945 mb was not reached until near landfall.)
At this time (20/1200 UTC) Imbudo was centred approximately 595 nm east-
southeast of the northern tip of Luzon, moving on an accelerating west-
northwesterly track at around 10 kts. (PAGASA had initiated warnings on
Imbudo at 19/0000 UTC, naming the cyclone Harurot with an initial
intensity of 65 kts. Also, at this time NMCC upgraded Imbudo to severe
tropical storm status, then to typhoon intensity at 19/1800 UTC. Both
agencies implement a 10-minute wind averaging period.) A 20/2119 UTC
SSM/I pass revealed well-defined concentric eyewalls, but water vapour
imagery showed that the TUTT cell to the east of Imbudo was weakening
and moving further away, no longer enhancing the poleward outflow
channel.
At 0000 UTC 21 July Imbudo had maintained its super typhoon title
with a MSW of 130 kts. The well-defined eye was tracking west-
northwestward at 12 kts (controlled by the mid-level steering of a
subtropical ridge centred near Okinawa) and was located 510 nm southeast
of the northern tip of Luzon, i.e. near 13.7N, 128.3E. By 21/2100 UTC
the 6-nm eye had reached a position about 160 nm east of Luzon, or near
15.6N, 124.4E. Microwave imagery prior to landfall revealed that the
system was undergoing a concentric eyewall cycle. By 22/0600 UTC Super
Typhoon Imbudo had struck the east coast of Luzon with all its strength
and might. (PAGASA's maximum 10-min avg intensity at landfall was 100
kts with the CP estimated at 941 mb.) Over land the cyclone's intensity
waned quickly with the MSW dropping to 80 kts at 1200 UTC. By 1800 UTC
Imbudo/Harurot had moved back over water again, having tracked across
Luzon, and with the MSW increasing to 90 kts. (By 23/0000 UTC Imbudo had
moved out of PAGASA's AOR and their final warning written.)
Strengthening then ceased and this (90 kts) was to be Imbudo's peak
intensity during the second part of its career.
At 0000 UTC on 23 July Typhoon Imbudo was crossing the South China
Sea, located approximately 270 nm southeast of Hong Kong, China, as it
continued on its west-northwesterly track at 17 kts. (HKO and CWB of
Taiwan had been including the tropical cyclone in their bulletins since
21/1800 UTC and 21/1200 UTC, respectively.) Microwave imagery indicated
that the system was once again re-organizing and strengthening. The MSW
remained at 90 kts, although it dipped slightly to 85 kts for one warning
cycle at 23/1200 UTC. At this time animated satellite imagery indicated
that the deep convection had decreased slightly during the previous six
hours. The intensity was raised again to 90 kts at 1800 UTC, by which
time dry air entrainment was noted in the northwestern quadrant in
enhanced infrared satellite animation imagery. The typhoon was then
passing 135 nm south of Hong Kong, China (21.1N, 111.9E). (HKO's and
NMCC's estimated MSW at this time was 90 kts, 10-min avg.)
The large, banding eye of Imbudo (as seen in enhanced multi-spectral
imagery) was about to make landfall in Guangdong province near the city
of Yangjiang at 24/0000 UTC. The official time of landfall, as noted in
the 24/0600 UTC warning, was 24/0100 UTC. Upon making landfall Typhoon
Imbudo weakened rapidly and was downgraded to a 55-kt tropical storm on
the final JTWC warning issued at 24/1200 UTC, located inland near 23.0N,
108.9E. NMCC continued to issue warnings on the weakening system
through the 24th, downgrading it first to a severe tropical storm at
24/0600 UTC, and then to a tropical storm at 24/1200 UTC. NMCC's final
bulletin was issued at 25/0000 UTC after their MSW (10-min avg) had
dropped to 30 kts (a tropical depression). HKO was also still monitoring
the dying storm, issuing their last bulletin at 24/1800 UTC after Imbudo
had passed out of their AOR. JMA followed Imbudo's progress into China,
issuing their final warning at 24/2100 UTC.
(Editor's Note: Both NMCC and HKO treated Imbudo as a more intense
system at landfall than did JTWC. NMCC's 10-min avg MSW of 90 kts and
HKO's 10-min avg MSW of 95 kts equate to 1-min avg MSW values of roughly
100 and 105 kts, respectively. JMA, on the other hand, lowered their
MSW estimate to 65 kts at 24/0000 UTC, shortly before landfall.)
C. Meteorological Observations
------------------------------
The following meteorological observations were all sent by Huang
Chunliang.
(1) Rainfall Observations
-------------------------
Station Province Rainfall Recording Period
or Region (mm) (UTC)
----------------------------------------------------------------------
Ding'an Hainan 230 23/0600 - 24/0600
Wenchang Hainan 213 23/0600 - 24/0600
Haikou Hainan 163 23/2100 - 24/2100
Dianbai Guangdong 108 23/2100 - 24/2100
Zhanjiang Guangdong 100 23/2100 - 24/2100
Gaozhou Met. Bureau Guangdong 203.1 24/0000 - 25/0000
Dongxing Guangxi 221 23/2100 - 24/2100
Lingshan Guangxi 217 23/2100 - 24/2100
Beihai Guangxi 137 23/2100 - 24/2100
Qinzhou Guangxi 113 23/2100 - 24/2100
Hepu Guangxi 343 23/1200 - 25/0000
Chih Pen, Taitung Cnty. Taiwan 137 21/1600 - 23/0600
Cheng Kung, Taitung Cnty. Taiwan 115 21/1600 - 23/0600
(2) Wind Observations
---------------------
The following are peak gust reports:
Station Peak Gust
---------------------------------------------
Shaba Town, Yangxi County 71 kts
Hailing Dao 76 kts
Shangchuan Dao 108 kts
Nansha, Guangzhou City 50 kts
Dongping Town, Yangjiang County 86 kts
Huazhou Meteorological Bureau 80 kts
Shiji Town, Panyu District, 58 kts
Guangzhou City
Based on NMCC warnings, the center of Typhoon Imbudo made landfall
near the counties of Yangxi and Dianbai, Guangdong Province, around
24/0200 UTC with MSW (10-min avg) of 38 m/sec (74 kts) and a CP of
960 hPa. Danzao, Nanhai District, Foshan City, reported a peak
sustained easterly wind of 18.9 m/sec (37 kts) at 24/0413 UTC with
a peak easterly gust of 29.2 m/sec (57 kts) at 24/0405 UTC. In the
Guangxi Zhuang Autonomous Region, twenty-one counties/cities had
reported winds of gale force or higher as of 25/0000 UTC. Among
those, a station in Heng County recorded a peak sustained wind of
39 kts while Guigang City recorded a peak gust of 64 kts.
D. Damage and Casualties
------------------------
(1) Philippines
---------------
Imbudo was the strongest typhoon to hit the Philippines in five
years. In October, 1998, Super Typhoon Zeb/Iliang claimed 83 lives,
and later that month Super Typhoon Babs/Loleng was responsible for
221 deaths. The highest death toll in the Philippines noted by the
author is twenty-one. A few days after the storm there were six
persons missing and unaccounted for. Eleven of the deaths (in the
Maguindanao and Sultan Kudarat areas) were attributed to flash flooding
while six (from Romblon in the central Philippines region and
Ilocos Norte province in the north) were caused by typhoon-related
accidents. Several areas suffered power failures (including Metro
Manila) caused by fallen power lines.
A total of 60 evacuation centres were required for 10,921 persons.
A total of 3,379 houses were partly damaged and 812 totally destroyed.
Most of the destruction occurred across northern and eastern parts of
the country.
Cost estimates so far include:
Agriculture/livestock - RDCC's report - 440.2 million pesos
DA's report - 1,098.6 billion pesos
Infrastructure - RDCC's report - 259.0 million pesos
DPWH's report - 7.0 million pesos
(2) China
---------
(a) Hainan Province
-------------------
Some 249,000 residents in 65 towns of six cities/counties (including
Haikou City, Wechang City, Ding'an County, Chengmai County, Danzhou
City, Lingao County, especially Haikou and Wechang) were affected by
the typhoon. Direct economic losses there were estimated at 55.35
million yuan. No casualties were reported in the province.
(b) Guangdong Province
----------------------
Some 381 towns of 7 cities were stricken by the typhoon with
4,776,100 residents being affected. The death toll from Typhoon
Imbudo had risen to eight when local governments assessed the cost
of the damage. More than 24 others were injured and three fishermen
were still missing as of the press report, according to the Guangdong
Provincial Anti-flooding Headquarters. Total direct economic losses
in the province were estimated at 1.9066 billion yuan with 595,000
houses collapsed. In Zhanjiang City, electricity and water supplies
were suspended in many counties and towns after power poles and
pumping stations were destroyed.
(c) Guangxi Zhuang Autonomous Region
------------------------------------
About 3,951,100 residents in Guangxi Region were affected by the
typhoon. Preliminary statistics indicate that Typhoon Imbudo killed
12 people due to falling trees and chimneys, landslides, and drowning.
Losses in the region amounted to 499.6 million yuan (equivalent to
$60.2 million US). Most areas of Guangxi, including the cities of
Yulin, Beihai, Qinzhou, Fangchenggang, Guigang, and Nanning experienced
heavy rainfalls. Also, according to official figures, 130 head of
livestock died due to Imbudo, some 4950 houses collapsed, and 116,000
hectares of crops were ruined.
An excellent report on Typhoon Imbudo can be found on the website
of the Hong Kong Observatory:
http://www.weather.gov.hk/informtc/imbudo/imbudo.htm>
Also, some reports on the storm's effects may be found at the
following URL:
http://www.reliefweb.int/w/rwb.nsf/vLND>
(Report written by Kevin Boyle with important contributions by
Huang Chunliang)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for July: 2 tropical depressions **
** - classified by IMD only
North Indian Ocean Tropical Activity for July
---------------------------------------------
On 27 July JTWC re-issued a STWO for the North Indian Ocean to include
an area of convection which had moved into the northern Arabian Sea from
the Pakistani coast. The development potential was assessed as fair, but
this was downgraded to poor later on the 27th after the convection had
significantly decreased around a possible LLCC. However, increased low-
level organization on the 28th brought about a re-classification of the
potential for development to fair, but the convection had essentially
dissipated by 24 hours later and the system was dropped as a suspect area
for tropical cyclone formation.
Early in August, Huang Chunliang informed me that IMD had classified
this system as a depression, and furthermore, that there had been a
circulation a few days earlier in the Bay of Bengal which had also been
treated as a depression. Before Chunliang could create and send me
tracks for these systems based on IMD bulletins, his computer was struck
by a virus which wiped out most of his files. Based on his memory and
a few notes which did survive, Chunliang sent me some information on
these North Indian systems. (A special thanks to Chunliang for sending
the information.)
On 25 July IMD upgraded a low-pressure area to depression status and
placed its center near 21.0N, 89.0E. A bulletin issued around 0700 UTC
on the 26th indicated that the depression had intensified into a "deep
depression" (i.e., 30 kts) during the late evening, crossed the North
Orissa coast and was centered near Balasore in Orissa state. This
system was never referenced by JTWC in their STWOs, and neither was it
listed as an "invest" area on NRL's tropical cyclone page.
The weakening system continued to move farther inland in a west-
northwesterly direction and was downgraded to a depression (25 kts) on
either the 26th or 27th. A bulletin at 28/0700 UTC mentioned intense
convective clouds over the northeast Arabian Sea off the Gujart coast
in association with the depression over northwest Madhya Pradesh about
100 km southwest of Guna. The system was downgraded to a low-pressure
area later on the 28th. It is interesting to note that the Pakistan
Meteorological Department (PMD) referred to the system as a monsoon
depression in a bulletin on the 28th.
Regarding the Arabian Sea disturbance mentioned in the first para-
graph above, IMD upgraded this system to depression status at 29/0300
UTC, placing the center near 21.5N, 64.5E. However, it soon weakened
and was downgraded to a low-pressure area on the 30th. (JTWC had
dropped it as a suspect area at 29/1800 UTC.) PMD also referred to this
system as a monsoon depression which brought heavy rains to northwest
India and neighboring southern Pakistan, triggering severe flooding in
Sindh Province and some other locations. As of the first week in August,
more than 230 deaths had been attributed to severe monsoonal flooding
in Pakistan. Several reports on the Pakistani flooding may be found
at the following website:
http://www.reliefweb.int/w/rwb.nsf/vLND>
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for July: No tropical cyclones
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for July: No tropical cyclones
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for July: No tropical cyclones
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for July: 1 subtropical LOW
South Pacific Tropical Activity for July
----------------------------------------
No out-of-season tropical cyclones formed in the South Pacific basin
during July, but there was a system around mid-month with some
characteristics of subtropical storms which brought very heavy rains and
high winds to the islands of New Caledonia. Thierry Lefort of Meteo
France reported that the upper-level cyclonic circulation reached the
surface and disturbed the tradewind flow without becoming involved with
any pre-existing surface fronts. Also, the strongest winds were well-
removed from the center of the LOW. Pete Donaldson of CPHC stated that
the system was very much like a Kona LOW of the Hawaiian Islands region.
Record rainfall amounts were recorded on the Loyaute Islands, which
are flat coral islands: 420 mm in 24 hours and 530 mm for the entire
event. A Meteo France station on the east coast of Grande Terre
recorded 10-min avg sustained winds of 49 kts with a peak gust of 64 kts.
(This reading was likely orographically influenced by the nearby range
of mountains.) On Ile des Pins, which is flat, a MSW of 39 kts was
recorded with gusts to 60 kts. Noumea, on the poleward side of the LOW
and adjacent to an anticyclone, measured peak gusts of 55 kts. Jeff
Callaghan reported that the 10-metre yacht Astrid had been dismasted
near 24.6S, 153.9E (near Fraser Island) by large waves generated by
the New Caledonia LOW, and that a large-scale air and sea search was
underway (on 17 July) for the vessel. (Thanks to Thierry and Jeff for
sharing this information.)
*************************************************************************
EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the July, 1998
summary. I don't normally include the Glossary in most months in
order to help keep them from being too long. If anyone would like to
receive a copy of the Glossary, please e-mail me and I'll be happy
to send them a copy.
*************************************************************************
AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
from the archive sites listed below. (Note: I do have a limited e-mail
distribution list for the track files. If anyone wishes to receive
these via e-mail, please send me a message.)
Both the summaries and the track files are standard text files
created in DOS editor. Download to disk and use a viewer such as
Notepad or DOS editor to view the files.
The first summary in this series covered the month of October,
1997. Back issues can be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Michael Pitt, and
Chris Landsea):
http://australiasevereweather.com/cyclones/>
http://www.typhoon2000.ph> OR http://64.235.42.210>
http://mpittweather.com>
ftp:// ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
Another website where much information about tropical cyclones may
be found is the website for the UK Meteorological Office. Their site
contains a lot of statistical information about tropical cyclones
globally on a monthly basis. The URL is:
http://www.met-office.gov.uk/sec2/sec2cyclone/sec2cyclone.html>
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the complete Annual Tropical
Cyclone Report (ATCR) for 2002 (2001-2002 season for the Southern
Hemisphere). ATCRs for earlier years are available also.
The URL is: http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2002 Atlantic and Eastern North Pacific
tropical cyclones; also, preliminary storm reports for all the 2002
Atlantic and Eastern North Pacific cyclones are now available, as
well as track charts and reports on storms from earlier years.
The URL is: http://www.nhc.noaa.gov>
A special thanks to Michael Bath of McLeans Ridges, New South Wales,
Australia, for assisting me with proofreading the summaries.
PREPARED BY
Gary Padgett
E-mail: [email protected]
Phone: 334-222-5327
John Wallace (Eastern North Pacific, North Indian Ocean, Western
Gulf of Mexico)
E-mail: [email protected]
Kevin Boyle (Eastern Atlantic, Western Northwest Pacific, South
China Sea)
E-mail: [email protected]
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: [email protected]
*************************************************************************
*************************************************************************
|
Document: summ0307.htm
Updated: 26th October 2006 |
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