MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
AUGUST, 2007
Part 2 of 2
(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.)
NOTE!!! The August summary is being issued in two installments. The
first covered the Atlantic and Northeast Pacific basins, plus contained
an extra feature. The second installment covers the Northwest Pacific
and North Indian Ocean basins.
*************************************************************************
AUGUST HIGHLIGHTS
--> Destructive hurricane strikes Windward Islands, Jamaica and Mexico
--> Weak tropical storm remnants re-intensify hundreds of miles inland
over Oklahoma
--> Major hurricane threatens Hawaii
--> Weak tropical storm brings flooding rains to Vietnam
--> Typhoon strikes Taiwan and Chinese mainland
--> Typhoon strikes Japan near Tokyo
*************************************************************************
WIKIPEDIA TROPICAL CYCLONE REPORTS
Short reports with satellite pictures and small-scale maps for all
tropical cyclones may be found at the following links:
http://en.wikipedia.org/wiki/2007_Atlantic_hurricane_season
http://en.wikipedia.org/wiki/2007_Pacific_hurricane_season
http://en.wikipedia.org/wiki/2007_Pacific_typhoon_season
http://en.wikipedia.org/wiki/2007_North_Indian_cyclone_season
http://en.wikipedia.org/wiki/2007-08_Southern_Hemisphere_tropical_cyclone_se
ason
For some storms more detailed reports have been prepared. In those cases
I will include the specific links in the reports for the applicable
tropical cyclones.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for August: 1 tropical depression **
2 tropical storms ++
1 intense hurricane
** - system became an intense hurricane in September
++ - one of these formed in July and became extratropical on 1 August
NOTE!!! The Atlantic basin was covered in the first installment of the
August summary.
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for August: 2 tropical storms
1 hurricane
1 intense hurricane
NOTE!!! The Northeast Pacific basin was covered in the first installment
of the August summary.
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for August: 7 tropical depressions **
2 tropical storms ++
3 typhoons ##
1 super typhoon
** - classified as tropical depressions by JMA only
++ - one of these classified as a tropical storm by JTWC only
## - one of these formed in July and continued operating into August
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). A very special thanks to Michael for the
assistance he so reliably provides.
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 August
----------------------------------------------
The month of August was quite active in the Northwest Pacific basin.
Five tropical storms formed with three reaching typhoon intensity. (One
of these was not named by JMA.) In addition, as the month began Typhoon
Usagi was prowling Western Pacific waters en route to a landfall in
Japan. The report on Usagi may be found in the July summary; however,
a couple of corrections to that report are given below.
Tropical Storm 06W was a fairly weak South China Sea tropical storm
which nonetheless was responsible for 60 or more deaths in Vietnam due
to flooding. JMA did not classify this system as a tropical storm, and
JTWC had it as a minimal tropical storm for only 12 hours, but QuikScat
data suggests that the cyclone may have been a little stronger than
reported by the warning agencies. Typhoon Pabuk sailed westward,
clipping the southern tip of Taiwan and brushing the southern Chinese
coastline early in the month, while at around the same time Tropical
Storm Wutip formed east of the Philippines and moved toward Taiwan.
The second week of August gave rise to mighty Super Typhoon Sepat which
ultimately made destructive strikes in Taiwan and in mainland China.
Late in the month, a reverse-oriented monsoon trough gave rise to Typhoon
Fitow, which continued operating into the second week of September and
made a significant strike on Honshu. Reports on all four named storms
plus the unnamed tropical storm follow.
In addition to the tropical storms and typhoons, no less than seven
systems were referenced as tropical depressions by JMA in their High Seas
bulletins. Brief synopses of these systems follow:
(1) TD of 10-12 August - The JMA High Seas Bulletin at 09/0600 UTC
referenced a weak tropical depression (1002 hPa) near 22N/126E,
moving west slowly, but the bulletins for the next two cycles
did not reference a tropical depression, nor even a low-pressure
area, in this vicinity. At 10/0000 UTC, a weak tropical depression
was placed near 25N/123E, moving slowly north. JTWC mentioned the
system in an interim STWO issued at 10/0100 UTC, locating an area
of convection about 65 nm southwest of Naha, Okinawa. QuikScat
data revealed a tight area of turning within the monsoon trough.
The depression commenced moving northward at an accelerating pace.
JTWC issued a TCFA at 10/2130 UTC for a LLCC located about 265 nm
west-northwest of Naha. Convection was concentrated in an area
of low-level convergence to the east of the tightest turning.
The small LLCC was located within a broader gyre-type circulation
with the strongest winds on the periphery of the larger circulation.
Early on the 11th the LLCC became more disorganized, and by 11/1300
UTC the LLCC, then located about 310 nm west of Sasebo, Japan, had
become fully-exposed west of a band of patchy convection. The system
was encountering a mid-latitude trough moving out of northeastern
China which was inducing increasing vertical shear and causing the
depression to accelerate northward. JTWC cancelled the TCFA at
11/1130 UTC, and JMA classified the system as extratropical at
12/0600 UTC in the Yellow Sea just west of Korea with the LOW
subsequently continuing northward, moving into northeastern China.
JMA estimated the peak MSW for this system at 30 kts. A track for
this tropical depression is included in the companion cyclone tracks
file.
(2) Weak TD of 11-12 August - The beginnings of this system can be traced
to an area of convection which persisted on 9 August approximately
740 nm east-northeast of Guam. Satellite imagery depicted a
developing LLCC with convection flaring on the periphery. The
disturbance over the next couple of days migrated west-northwestward
and by the 11th was located about 125 nm east of Iwo Jima. A fully-
closed LLCC had developed but convection was still not persisting
near the center; hence, JTWC's development potential remained 'poor'.
JMA first referenced the system as a weak tropical depression at
11/0000 UTC near 24N/143E. The system drifted slowly west-
northwestward on the 11th, but moved quickly (based on JMA's
bulletins) late on the 11th to near 27N/138E where it became quasi-
stationary. At 12/1200 UTC the depression was downgraded to a
low-pressure area.
(3) TD of 14-15 August - JMA tracked this system from near 26.2N/123.6E
(northeast of Taiwan) at 14/0000 UTC northward to near 38N/125E (in
the Yellow Sea just west of Korea) by 15/1200 UTC. No reference was
made to this disturbance in JTWC's STWOs, and given the latitude of
formation, it is highly likely that it was a non-tropical or hybrid
system. JMA estimated peak winds of 30 kts for this system. A track
for this tropical depression is included in the companion tropical
cyclone tracks file.
(4) Weak TD of 14-18 August - This system, treated as a weak tropical
depression by JMA, was first referenced at 14/1800 UTC when it was
located at 23N/115E, or on the south Chinese coast very near Hong
Kong. Based on JMA's positions, the system meandered very slowly
for several days over the northern South China Sea between Hong
Kong and Hainan Dao, being last mentioned at 18/0600 UTC near
21N/114E.
NOTE: I do not have available any STWOs issued by JTWC during this
period. Normally, I receive the outlooks via e-mail and store any
which contain a reference to any areas of disturbed weather. But
occasionally, due to some glitch in the system, the STWOs do not
arrive via e-mail, and I often forget to visit JTWC's website and
download them. However, I suspect that in this case, since the
system was so near the coast it was not considered a suspect area
for development by JTWC.
(5) TD of 21-25 August - This system was first referenced by JMA at
21/0000 UTC near 22N/136E, or well west of the northern Marianas.
The depression drifted slowly west-northwestward to near 25N/134E
at 22/0600 UTC. It then drifted very slowly west-southwestward for
the next two days to near 23N/127E by 24/0600 UTC. The next bulletin
at 24/1200 UTC relocated the center to 20N/128E (or else picked up
on a new LLCC). The final reference by JMA to this depression down-
graded it to a low-pressure area near 22N/127E at 25/0000 UTC.
JTWC first mentioned this system in an interim SWTO issued at 0000
UTC on 21 August. Convection was flaring over the northeastern
quadrant of a developing LLCC. The environment was fairly favorable
for strengthening, so the development potential was assessed as
'fair'. A TCFA was issued at 22/0230 UTC as the system continued
to exhibit improved convective organization. However, as the 22nd
wore on, a mid-latitude trough deepened over the Sea of Japan,
increasing the vertical shear over the disturbance. By 2100 UTC the
LLCC, located about 220 nm east-southeast of Naha, had become fully-
exposed. JTWC cancelled the TCFA and downgraded the potential for
development to 'poor'. Also, a TUTT cell over Okinawa was
contributing to convergence over the system, helping to suppress
convection.
JMA estimated the peak MSW for this depression at 30 kts. A track
for this system is included in the companion tropical cyclone tracks
file.
(6) Weak TD of 24 August - This weak system was mentioned only once in
JMA's bulletins, at 24/0600 UTC, when it was located near 21N/131E.
JTWC's STWO issued at the same hour mentioned the disturbance, which
was located about 385 nm south-southeast of Okinawa. A LLCC appeared
to be developing with an increase in convection near the center.
However, by 25/0600 UTC the convection had dissipated and the system
was dropped from the STWOs.
(7) Weak TD of 31 August-01 September - JMA's final tropical depression
for August was a weak, short-lived system that was likely a hybrid
LOW. The first reference was at 31/1800 UTC near 33N/172E, or
several hundred miles west-northwest of Midway. The depression was
moving west-northwestward at 15 kts, and at 0000 UTC on 1 September
had moved to near 34N/171W. However, this was the final reference
to the system in JMA's bulletins. This system was not mentioned
in any of JTWC's STWOs and was likely not tropical in character.
MINOR CORRECTIONS TO TYPHOON USAGI REPORT
-----------------------------------------
In the report for Typhoon Usagi in the July summary, in Section B
(Observations), a couple of corrections need to be made based upon
revised information received from Derrick Herndon. A wind observation
from Nyutubaru AFB of 030@35G72 kts was listed for 0500 UTC. The time
actually was 0449 UTC. And the elevation for the Seto station is
134 meters instead of 143 meters as originally given.
TROPICAL STORM
(TC-06W)
2 - 7 August
----------------------------------
A. Synoptic History
-------------------
At 0400 UTC 2 August JTWC issued a TCFA on a disturbance located
approximately 185 nm east of Nha Tang, Vietnam. Multi-spectral imagery
indicated a consolidating system with deep convection developing over a
well-defined but partially-exposed LLCC. Upper-level analysis revealed
a weak to moderate wind shear environment with a broad upper-level trough
above the disturbance. The first warning on Tropical Depression 06W was
issued at 02/1800 UTC, locating the centre about 140 nm southeast of Hue,
Vietnam.
Embedded in a slack steering flow, Tropical Depression 06W drifted
slowly and erratically on 3 August while continuing to exhibit an exposed
LLCC. It was upgraded to a 35-kt tropical storm at 0000 UTC 4 August
when a strong convective burst occurred southwest of the centre.
However, the system soon became virtually devoid of convection and was
downgraded back to tropical depression status at 04/1200 UTC. The
easterly shear kept up, preventing the system from regaining tropical
storm intensity. Tracking westwards, TD-06W reached the coast of
Vietnam, then abruptly turned north on 5 August. The dying storm then
headed northwestward early on 6 August and into the Gulf of Tonkin before
dissipating over Vietnam the next day. JTWC issued the final warning at
07/0600 UTC. JMA classified this system as a 30-kt tropical depression
beginning at 02/0600 UTC, but never upgraded to tropical storm intensity;
hence, the system was not named. (TD-06W formed and remained west of
PAGASA's AOR, so no name was assigned by that agency.) JMA carried the
system as a tropical depression inland into Vietnam, last referencing the
LOW at 07/1800 UTC.
B. Meteorological Observations
------------------------------
The author received some information from Derrick Herndon at CIMSS
concerning ship and QuikScat observations made in association with
Tropical Storm 06W. Following are Derrick's comments, slightly edited:
"I found a ship observation from ship DCCN2 at 11.2N/110.5E at 03/0600
UTC which reported winds of 270/52 kts and a pressure of 1002 mb. I
initially questioned this wind; however, QuikScat indicated winds of
40-50 kts on the southwest side of the circulation. An upgraded version
of the QuikScat algorithm was received from Paul Chang which showed that
many of these wind vectors were not rain-flagged. I do not know the
height of the anemometer for this ship, but it would appear that the
observation may have been valid, suggesting winds around 45 kts. AMSU
intensity estimates from both our algorithms and CIRA's algorithm, along
with the AODT, all indicated a MSLP of 995-998 mb, in agreement with the
surrounding ship observations. Pressures in southern Vietnam at this
time were 1008-1009 mb, and if the MSLP was indeed 996 mb, then a decent
gradient would have existed just off the Vietnamese coast. The lowest
pressure I could find at landfall was from station 59981 which reported
999 mb on the 3rd."
And later information from Derrick:
"Several ships reported observations near TS-06W. Ship MGRH9 reported
1007.6 mb with winds 270/37 kts 70 nm SW of the center at 02/1200 UTC.
The ship was located in the active convective region and QuikScat data
supports the winds. Ship DCCN2 reported a pressure of 1002 mb with winds
270/52 kts at 03/0600 UTC 150 nm SW of the center. (This observation
described in above paragraph.) This report now appears to have been
outside the strongest winds and thus the wind is suspect (perhaps
26 kts). Again, QuikScat supported winds of 40-45 kts on the 3rd. The
surrounding observations suggest that the lowest MSLP was about 995 mb
around 1200-1800 UTC on the 3rd. There were no significant observations
from the landfall in Vietnam, which occurred after the system had
significantly weakened."
A very special thanks to Derrick for the observations and analysis.
From this information, it appears that Tropical Storm 06W was stronger
and at tropical storm intensity for a longer period than reported in
JTWC's warnings.
C. Damage and Casualties
------------------------
News sources indicate that 60-70 people died in Vietnam as a
result of the extensive flooding caused by Tropical Storm 06W. The
Wikipedia report states that some portions of Vietnam received over
24 inches (610 mm) of rainfall for a storm total in association with
TC-06W, and that Hainan Dao received a total of 231.6 mm.
(Section A written by Kevin Boyle; Sections B and C added by Gary Padgett
with much information supplied by Derrick Herndon)
TYPHOON PABUK
(TC-07W / TY 0706 / CHEDENG)
4 - 14 August
------------------------------------------------
Pabuk: contributed by Laos, is the name of a large freshwater fish
that lives in the Mekong River
A. Synoptic History
-------------------
The origins of Typhoon Pabuk can be traced back to a disturbance
located approximately 440 nm northwest of Guam. It was first alluded
to in JTWC's STWO at 0800 UTC 4 August when multi-spectral satellite
imagery revealed flaring convection near a developing LLCC. Upper-
level analysis indicated low vertical shear and moderate divergence
aloft. The system drifted west-northwestwards and quickly organized.
A TCFA was issued at 05/0300 UTC after an extensive CDO had formed over
the centre. The disturbance was upgraded to a 35-kt tropical storm on
the first warning issued by JTWC at 05/0600 UTC. At the same time JMA
raised their 10-min avg MSW to 35 kts and assigned the name Pabuk.
(JMA had first identified Pabuk as a tropical depression at 04/1800
UTC). Pabuk was known locally in the Philippines by the name Chedeng.
Pabuk moved smartly across the Northwest Pacific on a predominantly
westerly trajectory, a straight-runner, and remained south of the
subtropical ridge axis. For most of its life, the tropical cyclone was
located on the northern side of a monsoon depression which was to later
spawn Tropical Storm Wutip. Tropical Storm Pabuk gradually
strengthened on 5-6 August, and was upgraded to a minimal typhoon at
0000 UTC 7 August, located approximately 285 nm southeast of Taipei,
Taiwan. This was to be its maximum intensity. The storm was briefly
downgraded to a 60-kt tropical storm at 07/1200 UTC, but was upgraded
back to typhoon intensity at 07/1800 UTC based on the appearance of a
small eye as depicted in Taiwan radar imagery.
After passing over the southern tip of Taiwan, Pabuk was downgraded
back down to a tropical storm at 08/0000 UTC. Once across the Taiwan
Strait, Pabuk flirted with the southern Chinese coast and passed just
south of Hong Kong late on 8 August. The system began to track more
slowly southwestwards, and was lowered to tropical depression status at
09/0600 UTC on what was initially JTWC's final warning. It was felt
that Pabuk was dissipating over land at this time. When infrared
imagery revealed that the centre had not moved inland, but in fact had
remained offshore and moved parallel to the Chinese coast, JTWC re-
issued a penultimate warning at 09/1200 UTC and relocated Pabuk further
to the south to a position 140 nm southwest of Hong Kong. The final
warning was issued at 09/1800 UTC.
The remnants of Pabuk drifted erratically over the next two days.
The system drifted slowly northwestward, passing very near Hong Kong
before meandering inland near Zhongshan, Guangdong Province, on 10
August. Abruptly turning northeastward, the 30-kt LOW crossed the
Pearl River Estuary, passing north of Hong Kong on 11 August. The
system accelerated east-northeastward over China before turning to the
northeast on 12 August, emerging into the East China Sea later that
same day. Pabuk's remnants entered the Yellow Sea early on 14 August
and were last noted in JMA's high seas bulletin at 0600 UTC on 14
August heading in a more northerly direction towards North Korea.
B. Observations
---------------
Following are some observations sent to the author by Derrick Herndon.
Again, a very special thanks to Derrick for sending the information.
"On the 7th Pabuk passed just south of Lan-yu located just east of the
southern tip of Taiwan. The station recorded a pressure of 979 mb at
1300 UTC while apparently in the northern eyewall, according to both
radar and microwave imagery. At 1600 UTC the station reported winds of
Force 8, gusting to Force 17, which equates to 37 kts gusting to 113 kts.
The station on the island is highly elevated at 325 meters. After
passing Lan-yu, the eye became quite small as the system intensified.
The very small eye (perhaps 7.5 nm) passed over southern Taiwan just
north of Henchun. Henchun reported 979 mb at 1700 UTC with west winds
of 41 kts (10-min avg) gusting to 57 kts. It appears that Henchun was
in the southern eyewall based on radar; however, the winds seem weak
even accounting for the station being on the weak side of the circu-
lation. The storm was moving at 15-20 kts, so that may account for some
of that discrepancy. The observation from Henchun suggests a MSLP of
964-970 mb. Taitung was located 44 nm north of the center and reported
999 mb at 1700 UTC. Using the 965 mb MSLP results in a gradient of
34 mb over 44 nm, from which I calculated a gradient wind of about
92 kts. The environmental pressure was about 1002 mb, so that 92-kt
MSW matches well with what would be expected for 965 mb. Since the
storm was moving at 15-20 kts and the RMW was quite small, I would
expect a slight upward deviation from the 92 kts to perhaps 100 kts.
This is a best guess based on the available data.
"After passing Taiwan Pabuk weakened significantly on the 8th. Ship
MLXD5, located 60 nm southeast of the center, reported 993.5 mb and
winds 260/37 kts at 08/1200 UTC. Buoy 22516 reported a MSLP of 998.1 mb
120 nm northeast of the center at 08/0300 UTC, and had earlier reported
a MSLP of 1000 mb while located about 60 nm south of the center at
06/1200 UTC."
C. Links and Comments
---------------------
A report on Typhoon Pabuk written by the Hong Kong Observatory can be
found at:
http://www.hko.gov.hk/informtc/pabuk/pabuk.htm
D. Damage and Casualties
------------------------
Pabuk brought much needed rain to southern parts of China, alleviating
the long drought that the region had been suffering from for many months.
However, flooding destroyed around 3,000 homes in Guangdong Province.
The storm also affected the cities of Zhanjiang, Maorning and Meizhou,
causing $170 million in economic losses and destroying more than 3,500
homes. One person was killed in Hong Kong.
Taiwan reported no casualties as a result of Typhoon Pabuk. The
storm disrupted power supplies to 3,000 households, otherwise, damage
was minimal.
Monsoonal rains enhanced by Pabuk caused flooding in the Philippines,
triggering landslides which killed 11 person.
(Sections A, C and D written by Kevin Boyle; Section B added by Gary
Padgett based on information supplied by Derrick Herndon)
TROPICAL STORM WUTIP
(TC-08W / TS 0707 / DODONG)
6 - 9 August
-----------------------------------------------
Wutip: contributed by Macau, is the Macanese word for butterfly
A. Synoptic History
-------------------
The tropical disturbance that spawned Wutip developed on the southern
flank of a monsoon depression which also included Typhoon Pabuk on its
northern periphery. It was first mentioned in JTWC's STWO at 2230 UTC
6 August when infrared satellite imagery indicated persistent deep
convection near a developing LLCC approximately 450 nm east of Manila,
Philippines. Upper-level analysis indicated a moderate wind shear
environment due to outflow from Typhoon Pabuk, but favourable diffluence
aloft, aided by strong low-level cyclonic shear, allowed the system
to organize. A TCFA was issued at 07/1000 UTC, and two hours later,
the first warning on Tropical Depression 08W was released with the
system drifting west-northwestward at 15 kts. The centre was located
approximately 330 nm east-northeast of Manila, or near 17.2N/126.1E.
JMA had first classified the system as a tropical depression near
14N/128E at 1800 UTC 6 August.
Drifting northwestward, Tropical Depression 08W was named Wutip at
0000 UTC 8 August when JMA raised their 10-min avg MSW to 35 kts. At
the same time, the cyclone was also dubbed Dodeng by PAGASA when the
storm had crossed into their AOR. JTWC upgraded Wutip to a 35-kt
tropical storm at 08/0600 UTC. Under the influence of subtropical
ridging that lay across the Northwest Pacific, Tropical Storm Wutip
tracked smartly northwestwards, reaching a peak intensity of 40 kts at
08/1800 UTC. Thereafter, strong upper-level shear, convergence aloft,
and interaction with Taiwan led to the system's rapid demise. The LLCC
was barely discernible when it reached the eastern coast of Taiwan early
on 9 August. (The JTWC position at 09/0600 UTC puts the center of Wutip
right over central Taiwan. However, the concurrent JMA position places
the center in the Pacific well off the east coast of the island.) On
9 August Wutip's very weak LLCC crossed Taiwan and was downgraded to a
tropical depression at 09/0600 UTC. The final warning was issued at
09/1800 UTC, locating the centre in the Taiwan Strait about 135 nm
west-southwest of Taipei.
B. Meteorological Observations
------------------------------
A ship (ID unknown) reported a MSLP of 1001.9 mb and winds 140/28 kts
at 07/0900 UTC, then 1004.4 mb and 110/33 kts at 07/1200 UTC while
passing southeast and east, respectively, of the developing center.
Stations ROIG and ROYN, located 120-150 nm northeast of the center,
reported winds sustained at 29-33 kts at 1200 UTC on 8 August. At
08/1700 UTC Taitung, Taiwan, reported a MSLP of 993 mb, and Pengjiayu
recorded sustained winds of 37 kts. (The above information sent by
Derrick Herndon.)
C. Damage and Casualties
------------------------
Tropical Storm Wutip brought torrential rainfall to the northern
Philippines which, added to the rains from Typhoon Pabuk, ended the
three-month drought there. This led to flash flooding and mudslides
which claimed three lives and injured 17 others. Over 10,000 people
were left homeless.
(Sections A and C written by Kevin Boyle; Section B added by Gary
Padgett based on information received from Derrick Herndon)
SUPER TYPHOON SEPAT
(TC-09W / TY 0708 / EGAY)
11 - 22 August
--------------------------------------------
Sepat: contributed by Malaysia, is the name of a freshwater fish
often found in rivers and swampy areas with lots of weeds,
and also in paddy fields
A. Synoptic History
-------------------
Super Typhoon Sepat originated as a disturbance in the monsoon
trough and was first mentioned in JTWC's STWO at 0600 UTC 11 August
when deep convection persisted northwest of a developing LLCC, located
approximately 695 nm southeast of Naha, Okinawa. (At the same time,
JMA identified the system as a tropical depression in their High Seas
Forecast.) Upper-level analysis revealed favourable divergence aloft
but moderate wind shear over the system. Further developments led to
the issuance of a TCFA at 11/2000 UTC, and the first warning was issued
at 12/0600 UTC, placing the centre of Tropical Depression 09W about 685
southeast of Okinawa and quasi-stationary. The slow-moving tropical
cyclone intensified, and was upgraded to a 40-kt tropical storm at
12/1200 UTC despite the hindering effects of the northerly shear and a
temporary loss of some of its deep convection. JMA upgraded the system
to tropical storm status at 12/1800 UTC, raising their 10-min avg MSW
to 35 kts and assigning the name Sepat. (Locally, in the Philippines,
the storm was known as Egay.)
Tropical Storm Sepat steadily intensified on 13 August while
tracking in a more westerly direction along the southern perimeter of
the subtropical ridge, and was upgraded to an 80-kt typhoon at 0000 UTC
14 August approximately 620 nm south-southeast of Naha, Okinawa. (JMA
also upgraded Sepat to typhoon status at the same time.) After
acquiring a 12-nm diameter eye late on 14 August, Sepat strengthened more
rapidly and was upped to super typhoon status at 15/0000 UTC before
reaching its maximum intensity of 140 kts eighteen hours later. At
this time Super Typhoon Sepat was located about 530 nm southeast of
Kaoshiung, Taiwan. Typhoon-force winds extended outward 55 nm from the
centre in all quadrants, and gales extended outward from 130-140 nm.
JMA estimated the minimum CP at 910 mb.
Moving on a north to north-northwesterly track, Sepat remained a
super typhoon for 30 hours, undergoing an eyewall replacement cycle
late on 16 August. Weakening began on 17 August as the storm continued
northwestward. Typhoon Sepat made landfall over Taiwan with a MSW of
105 kts at around 17/2100 UTC, then proceeded from there into
southeastern mainland China, making landfall roughly 550 km northeast
of Hong Kong 24 hours later. Sepat continued to weaken as it tracked
further inland. The former super typhoon was downgraded to a tropical
storm on JTWC's final warning at 19/0000 UTC. JMA downgraded Sepat to
a tropical depression at 20/0000 UTC, but continued to follow the
remnants as a depression through 22/1200 UTC when the weak LOW center
was located well-inland near 28N/112E.
B. Meteorological Observations
------------------------------
The following was received from Derrick Herndon:
"As Sepat passed NE of Lyudao, the station reported 10-min avg winds
of 47 kts, gusting to 70 kts, at 2000 UTC on the 17th. There was a
secondary peak in the wind 3 hours prior, possibly indicating a residual
double-eye structure. Chengong, Taiwan, experienced a direct hit by
Sepat. The station reported a pressure of 952 mb with winds 320/46 kts
(10-min avg) at 2100 UTC on the 17th. The winds then dropped off to
25 kts at 2200 UTC, then rose to sustained 57 kts at 2300 UTC as the
second eyewall passed. The system was weakening rapidly, thus the lowest
pressure reported by the station was when the center made landfall to the
north. While Sepat exhibited concentric eyewalls as it approached the
island, Taiwan radar indicated a single large eyewall at the time of
landfall. It appears the station was in the southern eyewall at this
time, so an estimate of the MSLP can be made. I would put the MSLP at
landfall around 933 mb.
"The buoy offshore Chengong also reported a maximum wave height of
6.9 meters and a storm surge of 3.5 meters. After crossing Taiwan, the
lowest pressure observed was from Penghu, which was 985 mb at 1200 UTC
on the 18th, supporting a central pressure at this time of 978 mb."
C. Links and Comments
---------------------
A detailed Wikipedia report available for Super Typhoon Sepat may be
accessed at the following URL:
http://en.wikipedia.org/wiki/Typhoon_Sepat_%282007%29
The following three microwave and AMSU images depict the eyewall
replacement cycle (ERC) which Sepat underwent on 16 August:
http://www.nrlmry.navy.mil/TC/tc07/WPAC/09W.SEPAT/ssmi/85h/1degreeticks/2007
0816.0937.f13.x.85h_1deg.09WSEPAT.140kts-918mb-179N-1261E.67pc.jpg
http://www.nrlmry.navy.mil/TC/tc07/WPAC/09W.SEPAT/tc_ssmis/91h/1degreeticks/
20070816.1151.f16.x.91h_1deg.09WSEPAT.140kts-918mb-179N-1261E.63pc.jpg
http://www.nrlmry.navy.mil/TC/tc07/WPAC/09W.SEPAT/amsub/color/2degreeticks/2
0070816.1235.metopa.x.color_89_150.09WSEPAT.135kts-922mb-187N-1256E.82pc.jpg
The link below is a wonderful animation which vividly reveals the
details of the ERC. The typhoon remains stationary at the center of the
image while the islands of Luzon and Taiwan slowly migrate toward the
south-southeast. Watch how the small, intense eyewall slowly begins to
erode as a spiral band begins to grow and transform into the new eyewall.
http://cimss.ssec.wisc.edu/tropic/real-time/marti/2007_09W/webManager/displa
yGifsBy12hr_08.html
D. Damage and Casualties
------------------------
According to the online Wikipedia report, Typhoon Sepat brought high
winds and torrential rain to Taiwan, resulting in numerous mudslides.
The storm caused an estimated US$34.5 million damage to agriculture,
and left 70,000 homes without electricity. The Suao-Hualien Highway
was closed due to landslides, and one person was reported dead.
According to Wikipedia's report, Sepat's winds felled billboards and
ripped roofs off houses in Fujian Province, killing two people. Also,
Sepat caused landslides in Fujian, leaving 12 people missing. In
Zhejiang a tornado killed 13 people and injured 60 others. Damage was
also reported in Jiangxi and Hunan, and damage in the four provinces
was estimated at 5 billion yuan (US$658 million). The overall death
toll was 39.
Floods caused by heavy monsoonal rains associated with Sepat caused
chaos in Metro Manila with at least three people reported dead.
(Sections A, C and D written by Kevin Boyle; Section B added by Gary
Padgett based on information received from Derrick Herndon)
TYPHOON FITOW
(TC-10W / TY 0709)
26 August - 9 September
-------------------------------------------
Fitow: contributed by the Federated States of Micronesia, is the
Yapese name for a beautiful fragrant flower
A. Synoptic History
-------------------
Typhoon Fitow stemmed from a disturbance located at the eastern end of
a reverse-oriented monsoon trough. JMA identified a weak tropical
depression at 26/0600 UTC several hundred miles east of the Marianas,
near 15N/151E. The system was referenced in JTWC's TCFA at 1630 UTC
28 August, located approximately 560 nm east-northeast of Saipan.
Remarks on this statement included: "Animated enhanced infrared satellite
imagery indicates deep convection banding into a LLCC with additional
convection forming near the center. The previous two Quikscat passes
have also depicted this LLCC with 15-20 kts of unflagged winds. Upper-
level analysis indicates weak vertical shear aloft. Poleward outflow
is being enhanced by TUTT cells to the north and northwest of the LLCC.
In addition to good poleward outflow, a ridge south of the LLCC is
enhancing equatorward outflow." The first warning on Tropical
Depression 10W was issued at 28/1800 UTC, the system moving
northeastward at 13 kts. JTWC upgraded TD-10W to a 35-kt tropical
storm at 29/0000 UTC with the centre located 675 nm northeast of
Saipan, moving northeastward at 14 kts. Six hours later, JMA raised
their 10-min avg MSW to 35 kts and named the system Fitow.
After its upgrade, the storm moved northeastward on 29 August before
turning northwards by early 30 August. Intensifying, the system was
upgraded to a 65-kt typhoon at 1800 UTC 29 August while located
approximately 860 nm east of Iwo Jima. At 31/0000 UTC Fitow slowed and
backed sharply onto a west-northwesterly heading, attaining an
intensity of 80 kts. The tropical cyclone weakened as it continued
slowly west-northwestwards due to the entrainment of drier air and the
MSW fell back to 70 kts on 31 August. Typhoon Fitow maintained 70-75 kt
winds for the next two days while meandering slowly westwards. After
breaking away from the monsoon cloud band on 1 September, the cyclone
began to re-intensify on 2 September and reached a peak intensity of
85 kts at 03/0600 UTC. A weakening trend began late on 3 September but
leveled out at 70 kts as Fitow passed close to Chichijima early on
4 September.
Typhoon Fitow gradually re-strengthened as it drifted west-
northwestwards on 4 September and onto a northwesterly heading the next
day. On 6 September the storm began to accelerate northwards under the
influence of a mid-level trough over Korea, and reached its peak
intensity of 85 kts for the second time at 0600 UTC 6 September while
located approximately 175 nm south-southwest of Tokyo, Japan.
Recurving north-northeastwards, Fitow made landfall over Japan as a
minimal typhoon late on 6 September. It was downgraded to a tropical
storm by both JTWC and JMA at 07/0000 UTC as it continued to race
north-northeastward over northern Honshu. JTWC issued their last
warning at 07/0600 UTC. Fitow crossed over the northernmost Japanese
island of Hokkaido later on the 7th and subsequently moved into the
North Pacific. JMA declared Fitow extratropical and issued their final
tropical cyclone warning at 08/0600 UTC. The extratropical remnants
of Fitow continued to diminish and had weakened into a 25-kt LOW near
46N/148E by 09/0000 UTC.
B. Meteorological Observations
------------------------------
Following are some observations and analysis from Derrick Herndon of
CIMSS (as always, a special thanks to Derrick for the information):
(Note: All winds are 10-minute average winds unless specified otherwise.)
Fitow passed about 50 miles north of Chichijima (RJAO) around 0800 UTC
on the 4th. This station only reports 3-hourly observations. At 0600
UTC the station reported 976 mb with winds 220@34G64 kts. At 0900 UTC
the pressure had only risen to 979 mb and winds decreased some to
250@33G58 kts. By 1200 UTC the pressure continued to rise to 985 mb and
winds also increased, apparently due to a stronger rainband with winds
220@44G66 kts. The station is located at 8 meters elevation. A
September 3rd 1549 UTC 37 GHz Aqua image strongly suggested a double
eyewall structure; however, this feature appeared to weaken with time
over the next 12-18 hours, leaving a larger eye and associated larger
radius of maximum winds while passing Chichijima. The station was on
the southern edge of the eyewall. Based on the station's pressure and
winds, the MSLP around 0600 UTC on the 3rd was likely below 968 mb and
probably close to 962 mb.
The center of Fitow made landfall in Honshu on the 6th near Irozaki
(47666). The station recorded sustained winds of 63 knots at 0900 UTC
with winds remaining at 56-58 knots sustained until 1200 UTC while the
station was within the northern eyewall of the large eye. Irozaki is
located at the southern tip of the Izu Peninsula, and the station is at
an elevation of 56 meters. A minimum pressure of 966.9 mb was recorded
at 1300 UTC with winds 080@27 kts, putting the MSLP at landfall around
964 mb. A 10-minute avg wind of 63 knots corresponds to a 1-minute avg
wind of about 69 knots. Stronger winds may have occurred to the east of
the center, thus I estimate the MSW at the time of landfall around
75 knots based on the observations.
Other observations from Fitow are listed below:
Hachijo-Jima (RJTH 95 meters): 0800 UTC - winds 18046G68 kts with a
pressure of 980 mb
Kozushima Airport (138 meters): 1100 UTC - winds 120@58 kts
Yokosuka (RJTX 53 meters): 1644 UTC - winds 160@54G73 kts with
a peak wind of 74 kts
One interesting aspect of this storm was the large spread in the
current intensity estimates with the AMSU-based estimates on the high
side and the ADT rather weak owing to the poor IR presentation and lack
of an eye in the IR. See the following link:
http://cimss.ssec.wisc.edu/tropic/satcon/10W.html
C. Links and Comments
---------------------
Typhoon Fitow followed an unusual S-shaped track typically associated
with a reverse monsoon trough. A paper describing unusual tropical
cyclone tracks, in particular the S-shaped track, written by Dr. Mark
Lander, can be found at this link:
http://ams.allenpress.com/perlserv/?request=get-abstract
<http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F1520
-0434(1996)011%3C0170:STCTTA%3E2.0.CO%3B2>
&doi=10.1175%2F1520-0434(1996)011%3C0170:STCTTA%3E2.0.CO%3B2
There is not a special, detailed Wikipedia report available for
Typhoon Fitow. However, the regular report (with additional links) may
be accessed at the following URL:
http://en.wikipedia.org/wiki/Typhoon_Fitow_%282007%29
D. Damage and Casualties
------------------------
According to the Wikipedia report, in Japan seven people were
killed, and at least 50 were injured as Fitow brought strong winds and
heavy rains. Over 80,000 houses experienced a power outage. Transport
in and around Tokyo was also affected, with nearly 200 flights cancelled
and many commuter trains suspended. In the Tama area west of central
Tokyo, flood warnings were issued for the Tama River, and many homeless
people who lived along its banks were swept away.
(Report written by Kevin Boyle with considerable information supplied by
Derrick Herndon)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for August: 1 deep depression **
** - no warnings issued on this system by JTWC
North Indian Ocean Tropical Activity for August
-----------------------------------------------
An area of convection developed and persisted on 4 August about
175 nm south of Calcutta, India. Satellite imagery indicated a broad,
partially-exposed LLCC lying within the monsoon trough over the northern
Bay of Bengal. With stronger winds along the southern periphery in
monsoonal flow and lighter winds near the core, the LOW was exhibiting
characteristics of a monsoon depression. At 0000 UTC 5 August, the IMD
classified the system as a depression. A SSMI microwave pass at 05/0130
UTC indicated convective banding wrapping south of the center from the
northwest with moderate vertical shear over the system. JTWC upped the
potential for development to 'fair' at 05/0600 UTC. A series of ASCAT
passes on the 5th indicated winds of 20-25 kts on the northern edge of
the LLCC with 30-kt winds on the southern periphery. IMD upgraded the
system to 'deep depression' status at 05/1800 UTC, implying 30-kt winds.
However, the depression moved westward and crossed the coast of India
during the morning of the 6th and subsequently began to weaken. A track
for this depression is included in the companion cyclone tracks file.
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for August: No tropical cyclones
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for August: No tropical cyclones
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for August: No tropical cyclones
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for August: No tropical cyclones
*************************************************************************
SPECIAL FEATURE - SOURCES OF TROPICAL CYCLONE INFORMATION
The purpose of this section is to list some websites where many and
varied types of tropical cyclone information are archived. Many readers
will know about these already, but for the benefit of those who don't,
I wanted to include them.
(1) Aircraft Reconnaissance Information
---------------------------------------
Various types of messages from reconnaissance aircraft may be
retrieved from the following FTP site:
ftp://ftp.nhc.noaa.gov/pub/products/nhc/recon/
Information regarding how to interpret the coded reconnaissance
messages may be found at the following URL:
http://www.nhc.noaa.gov/reconlist.shtml
Links are also included to websites with further information about the
U. S. Air Force 53rd Weather Reconnaissance Squadron and the NOAA Air-
craft Operations Center.
(2) Archived Advisories
-----------------------
All the advisory products (public advisories, forecast/advisories,
strike probabilities, discussions, various graphics) issued by TPC/NHC
are archived on TPC's website. For the current year (using 2004 as an
example), the archived products can be found at:
http://www.nhc.noaa.gov/archive/2004/index.shtml
Links to tropical products archives for earlier years are available at
the following URL:
http://www.nhc.noaa.gov/pastall.shtml
JTWC warnings for past storms are archived on the NRL Monterrey website:
http://www.nrlmry.navy.mil/tc_pages/tc_home.html
On the NRL site, the link to past years can be found in the upper left
corner of the screen.
I am not aware at the moment of any other TCWC which archives all
its tropical cyclone warning/advisory products for public access, but
if I learn of any, I will add them to this list.
(3) Satellite Imagery
---------------------
Satellite images of tropical cyclones in various sensor bands are
available on the NRL Monterrey and University of Wisconsin websites,
courtesy of Jeff Hawkins and Chris Velden and their associates. The
links are:
http://www.nrlmry.navy.mil/tc_pages/tc_home.html
http://cimss.ssec.wisc.edu/tropic/tropic.html
On the NRL site, the link to past years can be found in the upper left
corner of the screen. For the CIMSS site, a link to data archives is
located in the lower left portion of the screen.
Additional tropical satellite imagery, along with looping ability for
composite microwave imagery for the Western Hemisphere north of the
equator, can be found at:
(1) For the Eastern North Pacific:
http://www.ssd.noaa.gov/PS/TROP/trop-epac.html
(2) For the Atlantic, Gulf of Mexico and Caribbean Sea:
http://www.ssd.noaa.gov/PS/TROP/trop-atl.html
(4) Cyclone Tracking Information
--------------------------------
There is a U. S. Navy site that tracks tropical cyclones at 6-hourly
intervals which often includes pre and post-advisory positions. The
link to the site is:
http://www.nrlmry.navy.mil/atcf_web/doc_archives/
Steve Young has compiled many of these tracks onto a single webpage
which is very user-friendly:
http://home.earthlink.net/~shy9/tc1.htm
I'm sure there are other sites with available imagery available, and
as I learn of them, I will add the links to this list.
*************************************************************************
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 August, 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, Chris
Landsea, and John Diebolt):
http://australiasevereweather.com/cyclones/
http://www.typhoon2000.ph <http://www.typhoon2000.ph/>
http://mpittweather.com <http://mpittweather.com/>
ftp://ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/
http://www.tropicalcyclone2005.com/
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.metoffice.gov.uk/weather/tropicalcyclone
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the Annual Tropical Cyclone
Report (ATCR) for 2005 (2004-2005 season for the Southern Hemisphere).
ATCRs for earlier years are available also.
The URL is: http://metocph.nmci.navy.mil/jtwc.php
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2006 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2006 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 <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: garyp@alaweb.com
Phone: 334-222-5327
Kevin Boyle (Northwest Pacific)
E-mail: newchapelobservatory@btinternet.com
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: scla4255@bigpond.net.au
*************************************************************************
*************************************************************************
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