MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
JULY, 2007
(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.)
SPECIAL NOTE: With the February issue I began constructing the tropical
cyclone reports in a different format with the initial section presenting
various salient characteristics of the cyclones in a very structured,
template-like format. After a few months I began to realize that it
was requiring considerable extra time to draft this initial section, so
I polled about two dozen or so persons, soliciting their opinions
regarding the new "pro-forma" style of summaries. Of the persons who
responded, only one seemed to favor the new style, and his was a rather
weak opinion. The others really didn't care for it, and furthermore, I
discovered that my assistant writers, Kevin Boyle and Simon Clarke, felt
that it made writing the narrative history of the cyclones more difficult
in that they had to frequently double check to insure that they were not
duplicating information already presented. Therefore, effective with
the July summary, I am abandoning the structured, "pro-forma" style of
report and returning to the way we've always done things.
*************************************************************************
JULY HIGHLIGHTS
--> Two typhoons strike Japan
--> Unusual out-of-season South Indian Ocean tropical cyclone forms
--> First Eastern North Pacific hurricane of season forms
--> Former Atlantic tropical storm brings heavy rains to Newfoundland
*************************************************************************
CYCLONE TRACK GRAPHICS
John Diebolt of Tucson, Arizona, produces track graphics of all the
tropical and subtropical systems for which I prepare a tabular track in
the companion cyclone tracks file. These can be accessed at the
following URL:
http://www.tropicalcyclone2005.com/
Scroll down the chart to the month of interest and click on the green
bar under "Operational Track Image" for the desired system.
The tabular track of positions and intensities may also be obtained
from the above website, or from the other archival sites listed in
the Author's Note in the closing section of this summary.
NOTE!!! Due to extenuating personal circumstances, John has not yet been
able to get the July cyclone track graphics prepared. Hopefully, they
will appear on the website in the near future. Interested persons should
check the above link periodically.
*************************************************************************
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.
*************************************************************************
!!!!!!!!!!!! EXTRA FEATURE !!!!!!!!!!!!
HISTORY OF THE NAMING OF ATLANTIC TROPICAL CYCLONES
PART 1 - THE FABULOUS FIFTIES
A. Introduction
---------------
About eight years ago a query was posted to a discussion list
by a person interested in obtaining the complete sets of Atlantic
hurricane names for years prior to the establishment of the current
list of six rotating sets in 1979. The naming of tropical cyclones
has always been a keen side interest of mine, and many years earlier I
had collected from various sources the complete alphabetical lists
of Atlantic hurricane names dating all the way back to 1950--the first
year that Atlantic tropical cyclones were systematically named from an
alphabetical set of names.
In response to the above-mentioned query, I typed all the sets of
names as I had them, along with an explanatory document, and sent them
to that particular person. And over the years I've sent the
information to others who have expressed an interest in the old names.
So I've decided to prepare a series of monthly features detailing
the history of the naming of Atlantic tropical cyclones, plus one
feature describing the history of the naming of Eastern and Central
North Pacific cyclones. This month's feature will cover the period
1950-1959.
Prior to 1950 Atlantic hurricanes were occasionally called by
names, the most common practice being that followed in the Antilles
of calling storms after various saints in the Roman Catholic Church
on whose day a particular hurricane may have struck a given island,
(e.g., San Ciriaco, 1899; San Felipe, 1928; San Nicolas, 1931). But
the first year in which hurricane forecasters systematically named
tropical cyclones from a pre-determined alphabetical list was in
1950. During that season the old World War II phonetic alphabet
was utilized for naming tropical storms and hurricanes, and also for
the two years following. By 1952 another phonetic alphabet
had come into use--the original version of today's International
Phonetic Alphabet--and some confusion resulted when some parties
wanted to use the newer phonetic alphabet. So in 1953 forecasters
chose to try the practice which had been in use by typhoon fore-
casters in the Western Pacific since the closing days of World
War II of naming tropical cyclones with women's names. A set of
23 names, beginning with ALICE and ending with WALLIS, was drafted
for that year.
The tropical storm season of 1953 was active but mild--there were
no destructive hurricanes--and public reception to the idea seemed
rather favorable. So the same list was adopted for the 1954 season
with one change--the name GAIL was replaced with GILDA, most likely
because of confusion resulting from the term 'gale' being so widely
used in both tropical and extratropical storm warnings. In his
book "Hurricane Hunters", Ivan R. Tannehill relates that after the
destructive East Coast hurricanes of 1954, there was some public
criticism of the practice of using women's names as monikers for such
destructive storms, but after awhile the criticism died down and
forecasters continued using women's names in succeeding seasons.
With storms like CAROL, EDNA and HAZEL getting so much publicity,
forecasters had agreed to draft a new set of names for 1955. But
before the new list had been selected, an out-of-season hurricane
appeared in the Leeward Islands on January 2, 1955, so the name ALICE
was assigned to this hurricane. Before the regular season of 1955
began, forecasters drafted a new alphabetical set, beginning with
BRENDA and continuing all the way through the alphabet, ending with
ZELDA. For each season through 1959 a new set of names was selected.
The only names actually assigned to tropical cyclones that were
repeated prior to 1960 were EDITH and FLORA from 1955, which were
used again in 1959. Beginning in 1955 a restriction was put into
effect which required that hurricane names have exactly two syllables
and no more than six letters. This restriction considerably reduced
the number of names available, especially with letters for which there
was already a scarcity of names--the letter 'X' in particular. The
sets for 1957, 1958 and 1959 featured such unusual names as XMAY, XRAE
and XCEL.
B. Sources of Information
-------------------------
The information contained above and the lists of names themselves
came from several sources. The World War II phonetic alphabet and
the 1953/1954 set I copied down many years ago from Ivan R. Tannehill's
book "Hurricane Hunters". Tannehill was also the source for some of
the comments about early public reaction to the idea of naming storms
with women's names. The names for 1955 through 1958 I found in
various magazines in libraries. Since I wanted the names only for my
own personal interest, I didn't bother to annotate in what publication
I'd found the names. The set for 1959 I obtained from an issue of
"Weatherwise" which I ordered many years later while copies were still
in print.
C. The Sets of Names
--------------------
ATLANTIC HURRICANE NAME SETS
1950 - 1959
(An asterisk follows names that were actually assigned to storms.
A number in parentheses following a name refers to a note following
the lists.)
1950 1951 1952 1953 1954
---- ---- ---- ---- ----
Able * Able * Able * Alice * Alice *
Baker * Baker * Baker * Barbara * Barbara *
Charlie * Charlie * Charlie * Carol * Carol *
Dog * Dog * Dog * Dolly * Dolly *
Easy * Easy * Easy * Edna * Edna *
Fox * Fox * Fox * Florence * Florence *
George * George * George Gail * Gilda *
How * How * How Hazel * Hazel *
Item * Item * Item Irene Irene
Jig * Jig * Jig Jill Jill
King * King King Katherine Katherine
Love * Love Love Lucy Lucy
Mike * (1) Mike Mike Mabel Mabel
Nan Nan Nan Norma Norma
Oboe Oboe Oboe Orpha Orpha
Peter Peter Peter Patsy Patsy
Queen Queen Queen Queen Queen
Roger Roger Roger Rachel Rachel
Sugar Sugar Sugar Susie Susie
Tare Tare Tare Tina Tina
Uncle Uncle Uncle Una Una
Victor Victor Victor Vicky Vicky
William William William Wallis Wallis
Xray Xray Xray
Yoke Yoke Yoke
Zebra Zebra Zebra
1955 1956 1957 1958 1959
---- ---- ---- ---- ----
Alice * (2) Anna * Audrey * Alma * Arlene *
Brenda * Betsy * Bertha * Becky * Beulah *
Connie * Carla * Carrie * Cleo * Cindy *
Diane * Dora * Debbie * Daisy * Debra *
Edith * Ethel * Esther * Ella * Edith *
Flora * Flossy * Frieda * Fifi * Flora *
Gladys * Greta * Gracie Gerda * Gracie *
Hilda * Hattie Hannah Helene * Hannah *
Ione * Inez Inga Ilsa * Irene *
Janet * Judith Jessie Janice * Judith *
Katie * Kitty Kathie Katy Kristy
Linda Laura Lisa Lila Lois
Martha Molly Margo Milly Marsha
Nelly Nona Netty Nola Nellie
Orva Odette Odelle Orchid Orpha
Peggy Paula Parry Portia Penny
Queena Quenby Quinta Queeny Quella
Rosa Rhoda Roxie Rena Rachel
Stella Sadie Sandra Sherry Sophie
Trudy Terese Theo Thora Tanya
Ursa Ursel Undine Udele Udele
Verna Vesta Venus Virgy Vicky
Wilma Winny Wenda Wilna Wilma
Xenia Xina Xmay Xrae Xcel
Yvonne Yola Yasmin Yurith Yasmin
Zelda Zenda Zita Zorna Zasu
Notes:
(1) Air Force reports refer to a system in late October named Tropical
Storm Mike. However, this system does not appear in the current
HURDAT database, and the reason for its omission is not clearly
known.
(2) Hurricane Alice of 1955, named in early January, is now considered
a 1954 storm since it developed from a disturbance which has since
been traced back to late December, 1954.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for July: 1 tropical storm
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
-----------------------------------
Over the period 1950-2006, the month of July has averaged 0.9 NS per
year with 0.4 reaching hurricane intensity. Only three intense
hurricanes formed in the month during this period: Bertha of 1996, and
Dennis and Emily of 2005. During July, 2007, one tropical storm formed
on the final day of the month and did not reach hurricane intensity.
Tropical Storm Chantal was christened on the morning of the 31st south
of the Canadian Maritimes and became extratropical 24 hours later as it
sped toward southeastern Newfoundland. The post-tropical stage of
Chantal brought very heavy rains and gusty winds to the island. A report
on Tropical Storm Chantal follows.
During the first week of the month a tropical wave moved westward
across the Atlantic with an associated low-pressure area, and convective
activity increased on 3 July, leading to some prognostications that a
tropical depression might form within a couple of days. Tropical
cyclogenesis in the east-central tropical Atlantic is very rare in early
July, but it was in that region at the same time of year that the above-
mentioned Hurricane Bertha formed in 1996. The current disturbance,
however, began to look less organized on the 5th as environmental
conditions became less favorable and the system was dropped from NHC's
Tropical Weather Outlooks after 7 July.
TROPICAL STORM CHANTAL
(TC-03)
30 July - 4 August
------------------------------------------
A. Storm History
----------------
Tropical Storm Chantal ended an almost two-month hiatus in tropical
cyclone activity in the Atlantic basin when it formed late on 30 July
south of the Canadian Maritimes. Chantal, however, was destined to be
a short-lived system as it moved rather quickly toward Newfoundland.
Chantal's origin lay with an area of low pressure which had formed
north of the Bahamas on 28 July and with organization gradually
increasing as it tracked north-northeastward past Bermuda.
The initial TPC/NHC advisory, issued at 0300 UTC on 31 July, placed
the center of Tropical Depression 03 about 235 nm north-northwest of
Bermuda. Satellite imagery during the morning of the 31st revealed
that the system had strengthened, and a QuikScat pass just before
1000 UTC indicated winds in the 40-45 kt range. Hence, the depression
was upgraded to Tropical Storm Chantal in a special update issued at
31/1215 UTC. The newly-christened tropical storm was located about
285 nm south of Halifax, Nova Scotia, and moving quickly northeastward
at 20 kts. The initial intensity was set to 35 kts. Chantal reached
its peak intensity of 45 kts at 1500 UTC on 31 July while located
about 575 nm southwest of Cape Race, Newfoundland. The cyclone's
forward motion by this time had increased to 25 kts.
As the day wore on Chantal's track carried it over increasingly colder
SSTs and the storm began to rapidly transform into an extratropical
cyclone. The final advisory from TPC/NHC, issued at 0300 UTC on
1 August, placed the center of Chantal about 295 nm southwest of Cape
Race and moving northeastward at 28 kts. After extratropical transition,
the post-tropical storm continued to increase in intensity as it raced
northeastward. The center of the former Chantal crossed over Newfound-
land's Avalon Peninsula during the morning of 1 August, thence continuing
northeastward into the North Atlantic. Based on OPC's warnings, the
extratropical storm reached an intensity of 60 kts/965 mb at 03/0000
UTC near 59N/32W. Thereafter, the system began to weaken but was still
a 974-mb LOW to the south of Iceland near 60N/19W at 0600 UTC on the
4th of August.
A very detailed narrative history of Tropical Storm Chantal may be
found at the following link:
http://en.wikipedia.org/wiki/Tropical_Storm_Chantal_%282007%29
B. Storm Effects in Canada
--------------------------
Dr. Chris Fogarty, a forecaster at the Canadian Hurricane Centre in
Halifax, Nova Scotia, has kindly sent me some information about the
effects of Chantal in Canada which forms the basis for this section.
(A special thanks to Chris for sending the information.)
1. Track
--------
Following is a track for the latter tropical and post-tropical stages
prepared by Chris. I'm including it here for the benefit of interested
persons, but I am not going to re-work the track for Chantal which has
already been sent out in the companion cyclone tracks file which was
based upon TPC/NHC and OPC warnings.
Month Day Hour Lat Lon MSW CP
-------------------------------------------------
Jul 31 03Z 36.1N 66.0W 30 kts 1007 mb
Jul 31 09Z 37.8N 64.9W 40 kts 1000 mb
Jul 31 15Z 40.2N 62.7W 45 kts 999 mb
Jul 31 21Z 41.7N 61.2W 45 kts 999 mb
Aug 01 03Z 43.6N 58.5W 45 kts 994 mb
Aug 01 09Z 45.3N 55.5W 45 kts 993 mb Extratropical
Aug 01 15Z 47.2N 52.9W 45 kts 990 mb
Aug 01 21Z 49.8N 48.0W 45 kts 987 mb
Aug 02 03Z 52.0N 43.0W 50 kts 984 mb
Aug 02 09Z 56.0N 39.0W 50 kts 978 mb
2. Impacts in Newfoundland
--------------------------
After losing its tropical characteristics by 0600 UTC on 1 August,
the center of Post-tropical Chantal moved quickly toward Newfoundland's
Avalon Peninsula with the center arriving during the mid-morning that
day. Conditions were wet and windy along the shores of Avalon with most
of the heavy rain falling between midnight and midday over the Avalon
and Burin Peninsulas. Western portions of the Avalon Peninsula received
the heaviest falls (from 100 to 200 mm). The highest reported one-hour
falls were 43 mm at St. John's West and 49 mm at Mt. Pearl between
6:30 and 7:30 am on 01 August when the center of the storm was about
five hours away from crossing the Peninsula. Winds were not particularly
strong with Chantal, and were confined to the southern Avalon Peninsula,
with coastal gusts near 43 kts. An official peak gust of 37 kts was
recorded at Cape Race, and an unofficial gust of 48 kts was reported
at Cape Pine on the southern Avalon Peninsula.
The very heavy rains caused rivers and streams to swell quickly,
washing out several roads and bridges and isolating some communities from
the primary road network. Such instances were common over the western
part of the Avalon where the heaviest rainfall occurred. States of
emergency were declared for some towns including Placentia and South
River. There were many instances of water inundating low-lying areas,
particularly in St. John's. Storm drains were overwhelmed, and water
was forced through drain covers on some streets. The flooding was
severe enough to cause some structural damage to buildings.
For the Burin and Avalon Peninsulas, the normal July and August total
rainfall is about 200 mm. This essentially means that much of the
affected region received one to two months worth of summer rainfall in
the span of about 12 hours. Argentia reported 116 mm of rain in the
24 hours ending at 3:30 am (local time) 02 August. This is a record
one-day total for August based on the town's broken period of weather
data dating back to 1945. The old record was 62 mm on 19 August 1982.
In the southwestern Avalon community of Branch, 98 mm of rain fell,
breaking the previous one-day August total of 64 mm on 14 August 1990,
based on a period of record dating back to 1984.
3. Additional Rainfall Data
---------------------------
Some storm-total amounts:
Station Rainfall
------------------------------------
Argentia 200.4 mm
Whitbourne 189.3 mm
Salmonier Nature Park 115 mm
North Harbour 111 mm
Branch 97.6 mm
St. John's Airport 96.6 mm
St. John's West 93.2 mm
Brownsdale 65.8 mm
St. Lawrence 55.2 mm
Garnish 39.6 mm
Cape Race 28.3 mm
Bonavista 28.0 mm
For comparison the monthly average August rainfall for St. John's is
108.1 mm.
(Report written by Gary Padgett with significant contributions by
Chris Fogarty)
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for July: 3 tropical depressions **
1 tropical storm
1 hurricane
** - one of these became a named storm early in August
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
--------------------------------------------
Tropical activity for the month of July in the Northeast Pacific basin
was somewhat below normal during 2007. Over the period 1971-2006, the
month of July has produced an annual average of 3.7 NS, 1.9 H, and 1.1
IH. During July, 2007, there were two NS with one reaching hurricane
intensity, and no intense hurricanes. Tropical Storm Cosme formed far
to the southwest of Baja California on 15 July and briefly reached
minimal hurricane intensity the next day before beginning to weaken.
The residual depression moved westward and entered CPHC's area of warning
responsibility, moving south of Hawaii before finally dissipating near
Johnston Island. Tropical Storm Dalila formed far to the south of the
Gulf of California on the 23rd and pursued a general northwesterly
trajectory roughly parallel to the Mexican coastline. The cyclone peaked
at 50 kts on the 24th before encountering colder SSTs and weakening.
Short reports follow on both Cosme and Dalila.
Three other tropical depressions formed during the month. Tropical
Depression 04E was spawned by a tropical wave that emerged from the
coast of Africa on 23 June and reached the Pacific on 3 July. The
associated convection increased on 6 July and began to show signs of
organization the next day. A depression formed late on 9 July about
615 nm southwest of the southern tip of Baja California. A combination
of southwesterly vertical shear and decreasing SSTs along the track
prevented additional strengthening as the system tracked northwestward.
TD-04E turned westward late on 10 July and weakened to a non-convective
remnant LOW early the next day about 765 nm west-southwest of the tip
of Baja California.
Tropical Depression 05E developed from a tropical wave that moved
off the west coast of Africa on 21 June and entered the Eastern North
Pacific on 10 July. Disorganized convection associated with the wave
increased on 11 July. The wave moved westward and gradually became
better organized over the next couple of days, and a depression formed
at 1200 UTC 14 July about 200 nm south-southwest of the southern tip
of Baja California. Under the influence of vertical shear, the
depression was unable to strengthen further. The system continued
west-northwestward on 15 July, and cooler waters and a more stable
airmass resulted in its degenerating into a remnant LOW by 0000 UTC
on 16 July.
(NOTE: The information in the above two paragraphs was pretty much
taken verbatim from the TPC/NHC monthly summary for July. It seems
rather unusual that a tropical wave which departed the coast of Africa
on 23 June reached the Eastern Pacific on 3 July, whereas one which
exited Africa two days earlier did not enter the Pacific until 10 July.
I also checked the official reports on the two depressions which have
already been made available online on NHC's website, and the same dates
are given. I wrote the author of one of the reports inquiring about
the matter but have not yet received a reply. If I should receive an
answer, I will include it in next month's summary.)
Tropical Depression 08E formed on 31 July far to the southwest of
Baja California. The system gradually intensified and became Tropical
Storm Erick on 1 August. The report on Erick will be contained in the
August summary.
NOTE: The official TPC/NHC storm reports are already available online
for all the July systems. Links to the individual reports may be
found at the following URL:
http://www.nhc.noaa.gov/2007epac.shtml
HURRICANE COSME
(TC-06E)
14 - 23 July
-----------------------------------
The Northeastern Pacific basin's first hurricane of 2007 originated
from a tropical wave which was tracked with difficulty across the
Atlantic and Caribbean Sea due to a lack of associated convection. The
wave entered the Eastern North Pacific around 8 July and began to show
signs of organization on the 10th. The system continued westward and
had organized into Tropical Depression 06E by 14 July when located about
1175 nm southwest of Cabo San Lucas on the southern tip of the Baja
California Peninsula. TD-06E was a very large circulation which
initially moved slowly northwestward in response to a weakness in the
ridge to the north. The system gradually strengthened and was upgraded
to Tropical Storm Cosme at 1800 UTC on 15 July while located roughly
1200 nm southwest of Cabo San Lucas. The atmospheric environment was
conducive for further strengthening, and with a warm ocean, Cosme
reached hurricane intensity at 16/1800 UTC while centered approximately
1300 nm west-southwest of Cabo San Lucas, or about 1400 nm east of Hilo,
Hawaii.
By early on the 17th Cosme had turned to a westerly track in response
to a strengthening ridge to the north. However, the storm had also
entered into an environment of moderate easterly shear with SSTs having
dropped to around 25 C. Consequently, Cosme weakened rapidly with the
MSW dropping from 65 kts to 35 kts in only 18 hours. The cyclone
continued to weaken as it moved westward and was downgraded to a tropical
depression at 18/1800 UTC just prior to crossing 140W into the Central
North Pacific region at a point approximately 875 nm east-southeast of
Hilo. The former minimal hurricane was only a swirl of low clouds
that was completely devoid of deep convection as it entered the CPHC
area of warning responsibility. The depression continued moving toward
the west-northwest at around 13-17 kts during the next few days within
a hostile environment which did not allow it to regain tropical storm
intensity. Cosme passed well to the south of the Big Island on the
21st. Intermittent flare-ups of deep convection permitted the system
to maintain winds of about 30 kts for several days as it continued
westward across the Central North Pacific. Buoy 51002 reported seas
of 18 feet and an 8.5-min avg wind of 28 kts, gusting to 35 kts, on
21 July as the center of Cosme passed 56 nm to the south. By the 22nd
the depression finally succumbed to two days of very strong vertical
shear, and CPHC issued the final advisory at 23/0300 UTC, locating the
dissipating center just to the southeast of Johnston Island.
Even though Tropical Depression Cosme passed about 200 nm south of
Hilo, it transported a large area of moisture far to the north. The
interaction of this moisture brought much needed rain to parts of the
Big Island. Rainfall totals for the 48-hour period starting on the
morning of 20 July ranged from 75 to 180 mm in the Hilo and Puna
Districts, while totals from 25 to 75 mm were measured in the Kau
District. Gusty easterly winds also caused some tree limbs and small
trees to fall, resulting in temporary power outages to some areas of
the eastern Big Island. However, no significant damage or injuries
were reported.
(Report written by Gary Padgett)
TROPICAL STORM DALILA
(TC-07E)
22 - 27 July
-----------------------------------------
Tropical Storm Dalila developed from a tropical wave which entered
the Eastern North Pacific basin on 17 July. The wave spawned a broad
low-pressure area south of the Gulf of Tehuantepec on 19 July, which
subsequently moved slowly westward. Associated convective activity
increased on 21 July, and by early on 22 July the system had acquired
enough organization to be classified as a tropical depression. At
0000 UTC on 22 July TD-07E was located about 400 nm south of Manzanillo,
Mexico, with an initial intensity of 25 kts. Northeasterly shear
initially inhibited significant strengthening; however, by 0600 UTC
on 23 July the system had reached tropical storm intensity about 600 nm
south-southwest of Mazatlan and was named Dalila. A ridge over
northern Mexico steered Dalila northwestward during the next few days
while it slowly strengthened.
Tropical Storm Dalila reached a peak intensity of 50 kts at 1800 UTC
on 24 July while centered about 50 nm southeast of Socorro Island, or
approximately 350 nm south of Cabo San Lucas. After passing very near
Socorro, Dalila encountered cooler waters and began to weaken. On the
26th, while located about 210 nm southwest of the southern tip of Baja
California, the cyclone turned west-northwestward and weakened to a
tropical depression the next day. By later on the 27th Dalila had
degenerated into a remnant LOW and NHC issued the final advisory on
the system at 27/1500 UTC, locating the center about 450 nm west of
Cabo San Lucas. The remnant LOW subsequently moved west-northwestward
during the next few days and dissipated on 30 July.
No damage or casualties are known to have resulted from Tropical
Storm Dalila.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for July: 3 tropical depressions **
1 tropical storm
2 typhoons ++
** - classified as tropical depressions by JMA only
++ - one of these classified as a super typhoon by JTWC, but there are
some indications that this may have been an overestimate
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 July
--------------------------------------------
Three named tropical cyclones sprang to life in the Northwest Pacific
basin during July after a completely quiet June. Short-lived Tropical
Storm Toraji formed near Hainan Island and within about 24 hours had
crossed the Gulf of Tonkin and moved into Vietnam. Typhoon Man-yi
(known in the Philippines as Bebeng) formed early in the second week
of July very deep in the tropics to the south of Guam. Initially
moving west-northwestward, Man-yi passed roughly 175 nm north of Yap
early on 10 July as it was nearing typhoon intensity. The storm later
passed over Okinawa on 13 July near its peak intensity. (Man-yi was
twice upgraded to super typhoon status by JTWC, but there is some doubt
as to whether the cyclone ever reached 130 kts.) The storm later struck
the extreme southern portions of the Japanese islands of Kyushu and
Shikoku and brushed southern Honshu as it was weakening. Near the end
of the month Typhoon Usagi formed east of the northern Mariana Islands
and passed through the island chain as it was reaching typhoon intensity.
Usagi recurved toward southwestern Japan, becoming a respectable 120-kt
typhoon (per JTWC's analysis). After weakening some, the cyclone crossed
over eastern Kyushu and extreme western Honshu before becoming extra-
tropical in the Sea of Japan. Reports, authored by Kevin Boyle, follow
on the three named cyclones.
Three other systems were designated tropical depressions by JMA only.
One was in progress at the beginning of the month, and a discussion of
this system may be found in the introduction to the Northwest Pacific
basin in the June summary. On 25 July the remnants of ex-Tropical
Depression Cosme from the Central North Pacific crossed the Dateline,
and the JMA High Seas Bulletin at 25/0000 UTC referenced the LOW as a
weak tropical depression near 16N/180E. However, in the next bulletin
the system was listed as only a low-pressure area. The JMA High Seas
bulletin for 0000 UTC 27 July mentioned a weak tropical depression near
25N/135E, moving north at 10 kts. This was the only reference to this
system, and the latitude suggests it was probably more subtropical in
nature than purely tropical. No reference to this system was made in
any STWO from JTWC.
TROPICAL STORM TORAJI
(TC-03W / TS 0703)
3 - 6 July
-----------------------------------------
Toraji: contributed by DPR (North) Korea, is the name of a beautiful
flower which blooms unnoticed, usually found deep in the
mountains of Korea, and which is useful as food and medicine
A. Synoptic History
-------------------
Tropical Storm Toraji began as a persistent area of convection
located approximately 135 nm southeast of Hainan, and was initially
mentioned in JTWC's STWO at 0100 UTC 3 July. Animated multi-spectral
satellite imagery showed scattered deep convection south of a partially
exposed LLCC. Upper-level shear was assessed as weak to moderate with
fair equatorward outflow. Despite its close proximity to land, the
disturbance gradually consolidated, and following a 24-hour pressure
fall of over 5 hPa over Hainan, JTWC issued a TCFA at 04/0130 UTC. At
this time, the disturbance was located approximately 65 nm east-southeast
of Hainan. (JMA had first classified the system as a tropical depression
near 15N/112W at 0000 UTC 3 July.)
The first warning at 04/0600 UTC upgraded the disturbance to a 35-kt
tropical storm and positioned the centre approximately 50 nm southeast
of Hainan. Upon making landfall in Hainan Dao, Tropical Storm 03W was
downgraded to a tropical depression at 04/1200 UTC, and then re-instated
as a 35-kt tropical storm six hours later as it was emerging back over
water. JMA upgraded the depression to tropical storm status and
assigned the name Toraji at 05/0000 UTC, also estimating the MSW at
35 kts (10-min avg). Tropical Storm Toraji maintained this intensity
as it tracked northwestward and north-northwestward along the western
boundary of a subtropical ridge. The system crossed the Gulf of Tonkin
and made landfall in northeastern Vietnam before 1200 UTC on 5 July.
JTWC issued the final warning at 05/1200 UTC, downgrading Toraji to a
tropical depression, located approximately 155 km east-northeast of
Hanoi. The storm continued west-northwestwards over land and had
dissipated by 0000 UTC 6 July.
B. Meteorological data
----------------------
Weak surface wind reports suggest that Tropical Storm Toraji had no
significant impact in either Hainan or Vietnam.
C. Damage and casualties
------------------------
There were no reports of damage or casualties associated with Tropical
Storm Toraji. The Wikipedia report notes that Guangxi Province
evacuated 147,000 persons in response to the storm.
(Report written by Kevin Boyle)
TYPHOON MAN-YI
(TC-04W / TY 0407 / BEBENG)
7 - 20 July
-----------------------------------------------
Man-yi: contributed by Hong Kong, was originally the name of a strait.
With the construction of a dam, that part of the sea has become
a reservoir.
A. Synoptic History
-------------------
Typhoon Man-yi formed within a monsoon trough which lay from
the Philippines southeastward through Micronesia to around 160E. It was
first mentioned as a suspect area in JTWC's STWO at 1600 UTC 5 July
when satellite imagery indicated scattered convection developing around
a partially-exposed LLCC. A QuikScat pass indicated 10-15 kt winds south
of this weak centre. Upper-level analysis indicated moderate wind shear
and favourable divergence aloft. The disturbance gradually organized
while drifting westwards. A TCFA was issued at 07/0200 UTC with
strengthening convective bands to the south and to the northwest of the
centre. The first warning on Tropical Depression 04W was issued at
07/1200 UTC with the centre located approximately 500 nm south-southeast
of Guam. TD-04W progressed quickly to a 35-kt tropical storm six hours
later. However, JMA did not upgrade the depression to tropical storm
status and assign the name Man-yi until 1800 UTC 8 July. Even though
JMA uses a 10-min avg for their MSW estimates, they equate a Dvorak
rating of T2.5 to 35 kts, the same as the U. S. warning agencies. The
center fix positions between JTWC and JMA diverged fairly significantly
on 7 and 8 July, so this may have been one factor in the differing
intensity estimates.
Tropical Storm Man-yi drifted steadily on a west-northwest to westerly
course for several days along the southern flank of a mid-level
subtropical ridge. Slow intensification ensued and the storm finally
reached typhoon strength at 0600 UTC 10 July while located approximately
200 nm north of Yap. Man-yi continued to strengthen and an eye began
appearing early on 11 July as the storm entered PAGASA's AOR (where it
was known locally as Bebeng). Turning northwestward, then to the
north-northwest, Man-yi intensified at a more rapid pace and reached its
peak intensity of 135 kts at 12/1800 UTC while located about 75 nm south
of Naha, Okinawa. The typhoon subsequently passed northwards over
Okinawa shortly after 13/0000 UTC. After rounding the subtropical ridge
and recurving northeastwards, Man-yi began to weaken on 13 July.
Initially making landfall in Kagoshima, Kyushu, late on 13 July with
winds of about 85 kts, Man-yi then scraped along much of the southern
coastline of Japan. JTWC downgraded Man-yi to tropical storm intensity
at 14/1800 UTC before issuing the final warning twelve hours later, the
centre being then located about 80 nm south-southeast of Tokyo. However,
JMA maintained Man-yi as a tropical storm for another 36 hours, finally
classifying the system as a 40-kt extratropical gale at 17/0000 UTC while
located far to the east of Japan near 37N/153E. The gale continued
moving east-northeastward at a gradually slowing pace, and had weakened
to a 30-kt LOW near 44N/168E by 20/0600 UTC.
Man-yi was a larger than average system. For example, the wind
distribution in the JTWC 13/0600 UTC warning stated that sustained
typhoon-force winds extended up to 100 nm over the eastern semicircle
and the radius of gale-force winds extended over 200 nm also over the
same semicircle.
EDITOR'S NOTE: As noted in the narrative above, JTWC's peak estimated
intensity for Man-yi was 135 kts at 12/1800 UTC. However, there is
considerable evidence that this is an overestimation of the cyclone's
intensity; hence, I did not label Man-yi as a super typhoon in the
title line. Dr. Karl Hoarau performed a Dvorak analysis of Typhoon
Man-yi during the portion of the storm's history, and feels very
strongly that the storm's intensity at 12/1800 UTC was around 115 kts,
and near 100 kts when the centre was nearest Okinawa. Karl's peak
intensity of 125 kts was reached at 0000 and 0600 UTC on the 12th.
Following is a portion of the track file (prepared by the author)
around the time of peak intensity (KH = Karl Hoarau):
Date Time Lat Lon Cent MSW MSW Remarks
(GMT) Press 1-min 10-min
(mb) (kts) (kts)
-------------------------------------------------------------------------
07 JUL 11 0600 17.4 N 132.9 E 955 90 75
07 JUL 11 1200 18.9 N 131.5 E 955 100 75
07 JUL 11 1800 19.8 N 130.0 E 950 115 80
07 JUL 12 0000 21.0 N 129.1 E 935 120 90 KH: 125 kts
07 JUL 12 0600 22.2 N 128.6 E 930 125 95 KH: 125 kts
07 JUL 12 1200 23.6 N 128.0 E 930 125 95 KH: 115 kts
07 JUL 12 1800 24.9 N 127.4 E 930 135 95 KH: 115 kts
07 JUL 13 0000 26.0 N 127.4 E 930 125 95 KH: 100 kts/Nr Okinawa
07 JUL 13 0600 27.3 N 127.7 E 940 130 90 KH: 95 kts
07 JUL 13 1200 28.4 N 127.7 E 945 95 85 KH: 95 kts
07 JUL 13 1800 29.3 N 128.1 E 945 90 85
B. Observations
---------------
Gary forwarded some observations that he received from Derrick
Herndon. (A special thanks to Derrick for sending the information.)
"Naha recorded a pressure of 939 mb when the center passed about
15 miles to the west at 0100 UTC on the 13th. Winds at the time were
sustained at 35 kts (10-minute), putting the CP at about 930 mb.
Strongest winds at Naha were 220@62G82 kts at 0200 UTC as the station
experienced the second passage of the eyewall. These winds seem rather
weak given the MSLP and robustness of the eyewall on radar, even
accounting for the different time averaging. Kadena's strongest winds
were 200@66 kts at 0200 UTC with a gust to 91 kts at 0300 UTC on the
13th."
According to Karl Hoarau, Naha recorded a peak gust of 109 kts from
the ESE at 12/2314 UTC just before eye passage. (Karl's e-mail dated
the observation on 13 July, which would be true locally for Okinawa,
but the UTC date must obviously have been 12 July.)
For the landfall in mainland Japan:
"Man-yi made a direct hit on Kanoya AFB in southern Kyushu where winds
dropped off to 7 kts with 953 mb at 0500 UTC on the 14th. Strongest
winds there were 270@41G64 kts at an elevation of 68 meters. Aburatsu
(elevation 15 meters), which was in a better location to experience
stronger winds, had 200@63 kts 10-minute wind at 0600Z (no gusts
reported) with a pressure of 957 mb. Also Tanegeshima Island to the
south had a sustained wind of 61 kts. Farther upstream Murotomisaki
reported sustained winds of 140@64 kts at an elevation of 164 meters at
1200Z on the 14th. The center passed close to Miyakejima on the 15th at
0500 UTC when the stationed reported 977 mb. Strongest winds I could
find were to the south at Hachijojima where the station recorded winds
of 32G55 kts at 0000 UTC on the 15th."
C. Links and Comments
---------------------
There is not a special, detailed Wikipedia report available for
Typhoon Man-yi. However, the regular report (with additional links)
may be accessed at the following URL:
http://en.wikipedia.org/wiki/2007_Pacific_typhoon_season#Typhoon_Man-yi_.28B
ebeng.29
D. Damage and Casualties
------------------------
According to the Wikipedia report, three people died and six were
reported missing when a ship capsized 375 miles northwest of Guam. Also,
the storm resulted in 37 injuries and widespread power cuts on Okinawa.
A separate report by the BBC indicated that Man-yi was responsible for
3 deaths and 70 injuries on the southern Japanese islands of Kyushu and
Shikoku. Train and air services were disrupted and highways closed.
More than 300,000 people were evacuated.
(Report written by Kevin Boyle with additions by Gary Padgett)
TYPHOON USAGI
(TC-05W / TY 0507)
27 July - 7 August
--------------------------------------
Usagi: contributed by Japan, is the Japanese word for rabbit
A. Synoptic History
-------------------
The tropical disturbance that spawned Usagi was first mentioned as a
suspect area in JTWC's regular STWO at 0600 UTC 27 July when it was
located approximately 570 nm east-northeast of Saipan. Animated multi-
spectral imagery indicated a rapidly consolidating LLCC with flaring deep
convection. Upper-level analysis indicated low vertical wind shear and
good equatorward outflow, aided by a 200-mb anticyclone just to the
north. The development potential was set at 'fair'. Moving south-
westward, the disturbance continued to organize and JTWC issued a TCFA at
27/1330 UTC. The first warning on Tropical Depression 05W was issued at
28/1200 UTC, followed by an upgrade to tropical storm intensity six hours
later with the centre located approximately 235 nm northeast of Saipan,
moving west at 12 kts. JMA raised their 10-min avg MSW to 35 kts at
29/0600 UTC and dubbed the system Usagi.
Drifting westwards, Tropical Storm Usagi quickly intensified, and
after passing through the northern Marianas, was upgraded to a 65-kt
typhoon at 1800 UTC 29 July. (JMA's intensity, however, was only 45 kts
at the time, and it was 36 hours before that agency upgraded Usagi to
typhoon status.) Typhoon Usagi continued to strengthen over the next two
days while turning onto a northwesterly course along the southwestern
periphery of a low to mid-level subtropical ridge. The storm reached its
peak intensity of 120 kts at 01/0000 UTC while located approximately
250 nm west of Iwo Jima. (JMA's peak estimated 10-min avg MSW was
90 kts.) Steady weakening began later on 1 August as Usagi turned
north-northwestward towards a break in the subtropical ridge and into
a more hostile environment. The system made landfall in Kyushu, Japan,
at around 02/1200 UTC with a MSW of 75 kts. After tracking northward
across Kyushu, Usagi recurved northeastward into the Sea of Japan and
across northern Honshu before transforming into an extratropical LOW
on 4 August. Usagi's remnants intensified into a 50-kt extratropical
storm on 5 August as the system continued east-northeastward across
the North Pacific. The storm began to weaken on 6 August as it slowed
and turned to the north. By 1200 UTC on the 7th it had weakened to a
30-kt LOW in the Bering Sea east of the Kamchatka Peninsula.
At its peak Usagi was an average-sized typhoon with a 60-nm radius
of typhoon-force winds, and with gales covering a zone approximately
275 nm in diameter. The minimum CP estimated by JMA was 945 hPa.
B. Observations
---------------
Derrick Herndon passed along the following observations:
"The center passed about 25 miles north of Nyutabaru AFB which reported
a pressure of 968 mb with winds 290@31G44 kts on August 2nd at 0700Z.
The strongest winds from this station were 030@35G72 kts when the center
was to the east at 0500Z. The station is near the coast but at 82 meters
elevation. The pressure suggests a MSLP around 962 mb. Seto, located
in the straits between Shikoku and Kyushu Islands was better located to
experience the strongest winds and had sustained winds 120@60 kts;
however, this station is also elevated, being at 143 meters.
C. Links and Comments
---------------------
There is not a special, detailed Wikipedia report available for
Typhoon Usagi. However, the regular report (with additional links)
may be accessed at the following URL:
http://en.wikipedia.org/wiki/2007_Pacific_typhoon_season#Typhoon_Usagi
D. Damage and Casualties
------------------------
According to news reports, Usagi left 18 people injured in Kyushu.
Trees were felled, rivers were flooded, and thousands of homes were left
without power. Bullet trains from Honshu were suspended and a number
of flights were cancelled. There were no reports of casualties.
(Report written by Kevin Boyle)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for July: 1 deep depression **
** - no warnings issued on this system by JTWC
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. Occasionally some
information may be gleaned from the daily tropical weather outlooks
and other bulletins issued by the Indian Meteorological Department
(IMD), which is the World Meteorological Organization's Regional
Specialised Meteorological Centre (RSMC) for the basin.
The reported maximum sustained winds (MSW) are based on a 1-minute
averaging period, which is used by all U. S. civilian and military
weather services for tropical cyclone warnings. For synoptic
observations in the North Indian Ocean region, both 10-minute and
3-minute average winds are employed, but IMD makes no attempt to
modify the Dvorak scale for estimating tropical cyclone intensity;
hence, a 1-minute average MSW is implied. In the North Indian Ocean
basin JTWC usually does not initiate warnings until a system has
become well-organized and likely to attain tropical storm status
within 48 hours.
North Indian Ocean Tropical Activity for July
---------------------------------------------
A system which was likely more of a monsoon depression began to take
shape in the northern Bay of Bengal in early July. Early on 4 July the
IMD upgraded the low-pressure area to depression status, fixing the
center at 04/0300 UTC over the Bangladesh coast about 150 km southeast
of Kolkata (Calcutta). The system moved in a west-northwesterly
direction and 24 hours later lay over Gangetic West Bengal about 50 km
north of Kolkata. Even though inland, the system strengthened slightly
and had become a deep depression (30 kts) by 05/1200 UTC while remaining
practically stationary. The deep depression subsequently began to move
westward and by 0300 UTC on 6 July was close to Bankura. By early on
the 7th it had weakened back to depression status (25 kts) over North
Chhattisgarh, close to Ambikapur. The last reference by IMD available
to the author was at 0300 UTC on 8 July with the slowly weakening
system located over eastern Madhya Pradesh about 50 km southeast of
Sagar. According to the online Wikipedia report, the system was down-
graded to a low-pressure area later on the 8th, but experienced a brief
re-intensification to depression status the next day near Shivpuri in
northwestern Madhya Pradesh. However, it weakened again later that day
and the IMD issued its final bulletin.
JTWC mentioned the system in a STWO issued at 0900 UTC on 4 July, but
since the center of circulation was already inland in southwestern
Bangladesh, it was not considered a candidate for tropical cyclone
development. The Wikipedia report states that the system caused heavy
rains in the Calcutta area with 16 casualties. Almost 20% of the
cumulative rainfall for the entire monsoon season fell in three days.
Since the system was almost entirely an over land depression, I did
not prepare a track for it in the July cyclone tracks file. However,
I am including one below based on the few IMD bulletins I have available.
Storm Name: None Cyclone Number: None Basin: NIO
Date Time Lat Lon Cent MSW MSW Remarks
(GMT) Press 1-min 10-min
(mb) (kts) (kts)
-------------------------------------------------------------------------
07 JUL 04 0300 22.0 N 89.5 E 25
07 JUL 04 1200 23.0 N 89.5 E 25
07 JUL 05 0300 23.0 N 88.0 E 25
07 JUL 05 1200 23.0 N 88.0 E 30
07 JUL 06 0300 23.0 N 87.0 E 30
07 JUL 07 0300 23.5 N 83.5 E 25
07 JUL 08 0300 23.5 N 79.0 E 25
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for July: 1 tropical disturbance **
1 tropical storm ++
** - no warnings issued by MFR or JTWC
++ - classified as a tropical cyclone by JTWC and BoM Perth
Southwest Indian Ocean Tropical Activity for July
-------------------------------------------------
Organized tropical cyclonic systems are very rare in the South Indian
Ocean during the month of July, but during 2007, not one, but two systems
formed over waters west of 90E. The second of these, designated as
TC-01S by JTWC, formed in the extreme eastern portion of the basin and
eventually moved east of 90E into the AOR of BoM Perth. While not
treated as a tropical cyclone operationally by the Perth TCWC, during a
post-storm analysis the determination was made, based primarily upon
QuikScat data, that the system had in fact reached tropical cyclone
(i.e., tropical storm) intensity, and it is now officially classified as
an unnamed tropical cyclone. A report on TC-01S follows.
On 21 July, about a week prior to the formation of TC-01S, an area of
convection appeared approximately 110 nm east-northeast of Diego Garcia
and persisted. Animated EIR and AMSU data revealed a developing LLCC.
The system was located within a region of moderate vertical wind shear
with weak divergence aloft. The next day the center was fully-exposed,
but Diego Garcia had reported 24-hour pressure falls of almost 5 mb, and
a QuikScat pass at 22/0142 UTC had indicated strong gradient winds on
the southern periphery of the disturbance with strong convergence over
the southwestern quadrant; therefore, JTWC upped the potential for
development to 'fair' at 22/1030 UTC. Based on satellite fix bulletins
from JTWC, the peak winds during this phase were likely around 25 kts
(1-min avg). The system began to drift in a south-southwesterly
direction and gradually became better organized. By 1800 UTC on 23 July
the system was located approximately 95 nm south of Diego Garcia and the
LLCC was partially-exposed. However, by late on the 24th the system had
weakened and was no longer considered suspect for tropical cyclone
development.
Dvorak ratings from JTWC reached T2.0/2.0 at 22/1130 UTC, and peaked
at T2.5/2.5 at 22/1730 UTC, after which they began to decline. However,
Dvorak estimates from SAB were at T2.5/2.5 from 22/1430 through 23/0830
UTC. Based on consistent Dvorak T-numbers of T2.0 or higher from two
independent agencies, it is very likely that peak 1-min avg winds were
around 30 kts, and possibly could have reached 35 kts on the 22nd and
23rd. The track for this system (NRL Invest 90S) which I prepared for
the companion cyclone tracks file was based completely on satellite
fix bulletins issued by JTWC and SAB. Since neither MFR nor JTWC issued
warnings on this system, I refrained from assigning a MSW value of
35 kts, but winds to tropical storm-strength were possible considering
the intensity estimates from SAB and JTWC.
TROPICAL CYCLONE
(TC-01S)
27 - 31 July
------------------------------------
A tropical LOW formed in the Southwest Indian Ocean just east of 90E
in late July and intensified into a minimal tropical cyclone, as
analyzed by both JTWC and BoM Perth. Development to tropical depression
status and to near tropical storm intensity occurred in the AOR of Meteo
France La Reunion, but that agency did not consider it well-organized
enough to initiate warnings until it was on the verge of moving into
Perth's AOR. Although the latter agency did not name the system in real
time, it was upgraded to tropical cyclone status during a post-storm
review, mainly on the basis of QuikScat data.
A low formed within the near-equatorial trough on 26 July. QuikScat
data showed a broad trough near 4S/86E at 26/0100 UTC, and then a tighter
circulation with a well-defined LLCC at 26/1241 UTC. An area of
associated convection developed on 27 July approximately 810 nm east
of Diego Garcia, or a like distance northwest of the Cocos Islands.
Animated infrared imagery, a 27/1419 UTC SSMI microwave image, and a
27/1215 UTC QuikScat pass revealed loosely-organized convective banding
surrounding the LLCC. The system was located in a region of good
poleward outflow but with moderate vertical shear. Based on a JTWC
satellite fix bulletin, winds were likely about 25 kts (1-min avg).
AMSU data a few hours later revealed improved banding so the potential
for development was upgraded to 'fair' at 27/2230 UTC. As the system
drifted generally southeastward it continued to exhibit increased
organization, so JTWC issued a TCFA at 28/0230.
The system underwent a temporary weakening later on the 28th as the
center became exposed, but a second TCFA was issued at 29/0130 UTC.
The first JTWC warning on TC-01S was issued at 1800 UTC on 29 July with
the center located approximately 400 nm west-northwest of Cocos Island,
tracking south-southeastward at 15 kts. The system by now was already
west of 90E, and BoM Perth issued a gale warning at 30/0400 UTC,
estimating the maximum 10-min avg winds at 30 kts but forecast to
increase to gale force. JTWC's second and final warning was issued
at 30/0600 UTC, and while the MSW was still held at 35 kts, vertical
shear had increased and the system was forecast to quickly dissipate.
TC-01S reached its westernmost point around 1200 UTC 30 July when it
was located about 350 nm south of the Cocos Islands. Afterward the
system began to drift west-northwestward and weaken. The final Perth
warning at 31/0600 UTC placed the LOW very near 90E about 450 nm south-
southwest of Cocos.
The following information is taken from a preliminary report on the
storm prepared by BoM Perth and sent to the author by Joe Courtney. (A
special thanks to Joe for sending the report.) As noted above, the
Perth TCWC upgraded the LOW to tropical cyclone status based primarily
on QuikScat data instead of conventional Dvorak estimates. Cyclone
intensity is estimated to have been reached at 29/0600 UTC and continuing
through 30/0600 UTC. Dvorak estimates during this time ranged from T2.5
to T3.0. Operationally, the lower value was chosen, but upon re-analysis
the higher value was utilized, being biased from supporting QuikScat
images at 29/1100 and 29/2310 UTC. The former image captured only the
eastern part of the system, but some 30-40 kt wind flags showed up on
the eastern flank, which suggests that gales likely surrounded at least
half the LLCC. Ambiguity plots and NRCS wind speed plots from the latter
image also suggest that gales surrounded the center. Also, an ASCAT
image from 29/1500 UTC depicted 30-40 kt winds around the center.
The LOW formed over warmer-than-normal waters in excess of 28 C, but
as the system moved south of 10S is encountered SSTs of less than 27 C,
and during the 30th, when it reached 12S, the SSTs were estimated at
less than 25 C.
Following is a "best track" for the tropical cyclone prepared by the
Perth TCWC (abridged):
Year Mon Day Hour Lat Lon MSW Peak Cent
(UTC) (deg) (deg) 10-min Gusts Press
(kts)(kts) (hPa)
---------------------------------------------------------------------
2007 7 26 1200 3.0 S 86.3 E 20 45 1004
2007 7 26 1800 3.4 S 86.3 E 20 45 1004
2007 7 27 0000 3.7 S 86.2 E 25 45 1002
2007 7 27 0600 4.1 S 86.1 E 25 45 1000
2007 7 27 1200 4.4 S 86.1 E 25 45 1000
2007 7 27 1800 4.8 S 86.0 E 25 45 1000
2007 7 28 0000 5.3 S 86.0 E 25 45 1000
2007 7 28 0600 6.0 S 86.0 E 25 45 1000
2007 7 28 1200 6.6 S 86.5 E 25 45 1000
2007 7 28 1800 7.3 S 87.4 E 25 45 1000
2007 7 29 0000 8.1 S 88.4 E 30 45 998
2007 7 29 0600 9.0 S 89.0 E 35 50 994
2007 7 29 1200 9.8 S 89.9 E 40 55 992
2007 7 29 1800 10.4 S 90.4 E 40 55 992
2007 7 30 0000 11.0 S 91.2 E 40 55 992
2007 7 30 0300 11.2 S 91.6 E 35 50 994
2007 7 30 0600 11.7 S 91.7 E 35 50 994
2007 7 30 1200 12.1 S 91.6 E 30 45 998
2007 7 30 1800 12.3 S 91.0 E 30 45 998
2007 7 31 0000 12.2 S 90.3 E 25 45 1000
2007 7 31 0600 12.0 S 89.9 E 25 45 1000
2007 7 31 1200 12.0 S 89.6 E 25 45 1000
2007 7 31 1800 12.0 S 88.8 E 25 45 1004
2007 8 01 0000 12.0 S 87.9 E 25 45 1004
It should be noted that BoM Perth analyzed TC-01S to be a stronger
system than JTWC did (40-kt 10-min avg vs 35-kt 1-min avg).
TC-01S is only the second tropical cyclone on record to have formed
during July in the Western Australian Region. The other was Tropical
Cyclone Lindsay, which occurred in the same general region on 10-11 July
1996 and was at minimal tropical cyclone intensity for only 21 hours.
The BoM report concludes with the following very true and relevant
statement: "It is arguable that without QuikScat imagery that this
system would not have been classified as a tropical cyclone going by
imagery alone. This type of system may not be represented in the
historical database, which is significant when making conclusions about
trends in the frequency of tropical cyclones."
(Report written by Gary Padgett with significant contributions from
Joe Courtney)
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for July: 1 tropical cyclone **
** - Moved into Perth's AOR from west of 90E
Northwest Australia/Southeast Indian Ocean
Tropical Activity for July
------------------------------------------
A system being carried as a minimal tropical storm by JTWC (numbered
TC-01S) moved into the Perth AOR on 30 July. Gale warnings were issued
as a precaution in case the system should intensify into a tropical
cyclone (10-min avg winds of 34 kts or higher). The LOW was not named
operationally, but during a post-storm analysis it was determined that
the system had been a short-lived tropical cyclone. A report on this
unnamed tropical cyclone may be found in the preceding section covering
the Southwest Indian Ocean basin.
*************************************************************************
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: 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/
These tracks are often updated as further analysis occurs and may be
considered as sort of a working "best track".
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: https://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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