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TYPHOON '99 ARCHIVES
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MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
JUNE, 1999
(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.)
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JUNE HIGHLIGHTS
--> Quiet month overall--typhoon affects Philippines and China
while Atlantic and Northeast Pacific tropical seasons get
underway
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ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for June: 1 tropical storm
NOTE: Much of the information presented below was obtained from the
TPC/NHC discussion bulletins issued with every regular advisory. All
references to sustained winds imply a 1-min averaging period unless
otherwise noted.
Atlantic Activity for June
--------------------------
The 1999 Atlantic tropical cyclone season got underway a little
earlier than average when Tropical Storm Arlene developed in the
subtropical Atlantic about 475 nm southeast of Bermuda on 11 June.
Arlene posed a slight threat to Bermuda, but had weakened to a
tropical depression by the time of its closest approach to the island.
No other depressions or storms were tracked during the month, although
there were some rather impressive tropical waves which moved off the
west African coast.
Tropical Storm Arlene (TC #01)
11 - 18 June
-------------------------------
Arlene formed from a non-tropical disturbance along a decaying
front. A broad area of low pressure in association with an upper-
level LOW was noted several hundred miles northeast of Puerto Rico
on 8 Jun. By the 10th the disturbance was moving slowly to the
north-northwest and had become better organized. On 11 Jun the
center re-formed to the northeast near an area of deep convection
and the system rapidly strengthened, becoming a tropical depression
by 1800 UTC about 475 nm southeast of Bermuda. Considerable banding
surrounded a ragged CDO and outflow was impressive. TPC/NHC began
issuing advisories on the depression at 2100 UTC.
By the morning of 12 Jun convection had increased near the center
and Dvorak numbers from SAB and TAFB were 2.5, so the depression
was upgraded to Tropical Storm Arlene at 1500 UTC. Arlene was
centered at this time about 450 nm east-southeast of Bermuda. The
storm initially drifted very slowly and somewhat erratically northward
through 13/1200 UTC, at which time it made an abrupt turn to the west.
The storm was caught at first in a weak steering environment between
two mid/upper-level LOWs, but eventually came under the influence
of a mid-tropospheric subtropical ridge to the north.
Arlene's organization continued to improve through the night of
12-13 Jun--outflow was good, there was no shearing, and the main low-
level inflow was from the south and southeast with little to no
inflow from a stable airmass to the north. The storm reached its
peak intensity of 50 kts for the first time at 0600 UTC on 13 Jun.
Early on the 13th the cloud pattern looked quite healthy with cloud
tops of -70 C. But by mid-morning some shearing was evident as the
low-level center was located near the northwest edge of the CDO.
The Tropical Weather Discussion at 14/0300 UTC indicated that
scatterometer data showed winds to be less than 50 kts around the
system, so the MSW was decreased to 45 kts. The central pressure,
which had been previously reported at 1000 mb, was raised to 1009 mb
based upon ship reports which showed environmental pressures to be
quite high.
As Arlene continued slowly westward vertical shear increased
enough to inhibit strengthening but not enough to dissipate the storm;
hence, Arlene maintained a more or less steady state for a couple of
days. A Tropical Storm Watch was issued for Bermuda at 1500 UTC on
14 Jun as the forecast track was projected to carry the storm fairly
near the island. There may have been multiple centers late on the
14th as SAB and TAFB fixes were 50 nm apart. The first investigation
of the storm by U. S. Air Force Reserves Hurricane Hunters around
1200 UTC on 15 Jun found winds of 51 kts at 300 m, but a flight 12 hrs
later found winds to 55 kts at 450 m in the northeast quadrant;
therefore, the MSW was increased once more to 50 kts at 16/0000 UTC
with the storm centered about 200 nm southeast of Bermuda.
Arlene's motion was slow and erratic on 15 Jun, but by early on the
16th the storm began to move to the north-northwest, eventually curving
to the north and northeast around the mid-Atlantic subtropical ridge.
Arlene's intensity began to decline later in the day as vertical
shear increased. Convection diminished, possibly due to the storm's
location in an area of confluent upper-level flow to the north of a
large upper-level cyclone to Arlene's south. It was thought that the
associated subsidence might be a factor in inhibiting the development
of any new convection. Vertical shear increased and Arlene was
downgraded to a tropical depression at 0900 UTC on 17 Jun as it was
moving northward about 100 nm due east of Bermuda. The weakening
depression turned to the north-northeast and was losing its identity
by 18/0000 UTC about 250 nm northeast of Bermuda. No winds anywhere
near gale force were reported from Bermuda, and the lowest pressure
there was around 1017 or 1018 mb. (Thanks to Jack Beven for sending
me this information.)
Tropical Storm Arlene is the first known June tropical storm to
form so far north and east in the Atlantic. The vast majority of
June tropical developments have been in the Gulf of Mexico and in the
Western Caribbean. There have been only two tropical storms to form
in June east of the Lesser Antilles this century, and there have been
a few that have formed in the Bahamas and over the warm Gulf Stream
waters just off the southeastern U. S. coast. However, there have
been several late season (November) and out-of-season tropical cyclone
developments in the general area between Hispaniola and Bermuda and
eastward for a thousand miles or so, so it is very possible that in
pre-satellite days a tropical storm could have formed during June
in this area and remained undetected or else considered to have been
an extratropical gale.
John Wallace of San Antonio, Texas, checked back through the records
and sent me the observation that Arlene is only the second June
tropical cyclone on record to move near Bermuda, and the first one
to approach the island from the east. The other June cyclone to pass
near Bermuda was Hurricane Brenda of 1968, which passed well to the
north of the island as it headed eastward across the Atlantic.
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NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for June: 1 hurricane
NOTE: Much of the information presented below was obtained from the
TPC/NHC discussion bulletins issued with every regular advisory (CPHC
for locations west of 140W.) All references to sustained winds imply
a 1-min averaging period unless otherwise noted.
Northeast Pacific Activity for June
-----------------------------------
The Eastern North Pacific tropical cyclone season was a little
later than normal getting underway for the second year in a row.
Since 1966, when complete operational satellite coverage began for
this region, the median date for the beginning of the first tropical
storm/hurricane has been 1 June. Of the thirty-three seasons
from 1966 through 1998, the first cyclone formed in May in fifteen
years--almost 50% of the time. The earliest beginning season on
record was in 1990, when Hurricane Alma formed on 12 May, while the
latest season to begin was in 1969, when Tropical Storm Ava formed on
1 July. Only three seasons have had a later starting date than
1999 with one season (1994) beginning on the same date. One storm,
Hurricane Adrian, was tracked during the month. On the average
about two or three tropical cyclones develop during the month of
June in the Eastern North Pacific.
Hurricane Adrian (TC-01E)
18 - 22 June
--------------------------
An area of disturbed weather south of the Gulf of Tehuantepec was
mentioned in a Tropical Weather Outlook by TPC/NHC at 1700 UTC on
16 Jun. Over the next couple of days the area drifted slowly west-
ward just offshore with the possibility of heavy rains forecast for
the Mexican coastline east of Acapulco. By early on 18 Jun the
system was located about 250 nm south-southeast of Acapulco and had
become sufficiently organized that depression advisories were
initiated by TPC/NHC at 0900 UTC. The depression displayed a band
of very deep convection near and west of the low-level center with
cloud top temperatures to -85 C. A large mid/upper-level HIGH over
Mexico steered the system on a fairly steady west-northwesterly course
parallel to the Mexican coast.
Moderate easterly shear inhibited intensification initially and
the depression's center was difficult to track--there was considerable
scatter in the fixes provided by different satellite analysts--but by
the afternoon of the 18th the shear had relaxed somewhat and the
system was strengthening, being upgraded to Tropical Storm Adrian
at 2100 UTC. The storm's center seemed to re-organize to the north
a bit to a position about 150 nm south of Acapulco. Outflow was
well-established in all quadrants except the eastern one. Initially
the center was still not well-defined. Deep convection warmed
considerably and what had been a large CDO feature fragmented into a
chaotic pattern during the night, but by very early on the 19th a
small area of convection began to grow near Adrian's center and the
tropical storm began to intensify more rapidly.
By 1800 UTC on 19 Jun Dvorak numbers from TAFB and SAB had reached
4.0 and 3.5, respectively--implying that Adrian was, or almost was, a
hurricane. However, a ship (FNCM), located 35 nm northwest of the
center and moving south, reported winds of only 27 kts, so TPC/NHC
waited one advisory period before upgrading Adrian to a hurricane.
Adrian was estimated to have reached hurricane intensity by 20/0000
UTC when it was located about 200 nm southwest of Manzanillo, Mexico.
The hurricane continued to intensify and reached its estimated peak
MSW of 85 kts and central pressure of 975 mb at 1800 UTC on 20 Jun.
Adrian's center was approximately 300 nm south of Cabo San Lucas
at this time with an eye readily apparent in satellite imagery.
However, shortly after reaching its peak intensity, Adrian entered
a region of cooler SSTs and began to weaken rather rapidly. Six hours
after peaking the eye was no longer discernible and deep convection
had diminished and cloud tops were warming. The storm was also
beginning to be affected by southeasterly shear. The first visible
satellite pictures on 21 Jun required a relocation to the east of
the previous position. Adrian was downgraded to a rapidly weakening
tropical storm at 1800 UTC. The storm was by that time only a swirl
of low-level clouds with no associated deep convection. A late
observation from Socorro Island reported a wind of 70/40 kts and
a pressure of 993 mb at 1200 UTC.
Adrian's forward motion had slowed throughout the 21st and the
dying cyclone became quasi-stationary roughly 300 nm south-southwest
of Cabo San Lucas by 0600 UTC on 22 Jun. The latest high-resolution
cloud motion vectors from the University of Wisconsin indicated winds
of only about 20 kts with a few spots of 30-kt winds, so Adrian was
downgraded to a dissipating depression. The final advisory was issued
at 22/2100 UTC.
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NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for June: 1 tropical depression **
1 typhoon
** - classified as a tropical depression only by PAGASA. Neither
JTWC nor JMA carried the system as a depression.
NOTE: Most of the information on each cyclone's history presented in
the narrative will be based upon JTWC's advisories, and references to
winds should be understood as a 1-min avg MSW unless otherwise noted.
However, in the accompanying tracking document I have made comparisons
of coordinates with JMA (Japan) and the Philippines (PAGASA) when their
positions differed from JTWC's by usually 40-50 nm or more. Also, as
announced earlier in a separate posting, a column of 10-min avg MSW
is included--the values being obtained from either PAGASA's or JMA's
advisories. A special thanks to Michael V. Padua, owner of the Typhoon
'99 webpage, for sending me the PAGASA and JMA tracks.
In the title line for each storm I plan to reference all the cyclone
names/numbers I have available: JTWC's depression number and name (if
any), JMA's tropical storm numeric designator, and PAGASA's name for
systems forming in or passing through their area of responsibility.
Northwest Pacific Activity for June
-----------------------------------
Typhoon Maggie/Etang during the first week of the month was the
only tropical cyclone of tropical storm or typhoon strength to develop
in the Northwest Pacific basin during June. Maggie became a fairly
impressive typhoon with winds up to 105 kts as it passed through the
Luzon Straits. Also, during the first week of the month, a broad
monsoon-type depression formed in the South China Sea. JTWC never
issued warnings on this system but PAGASA named the system Gening and
issued bulletins from the 4th to the 6th of June. Tropical Depression
Gening remained quasi-stationary in the central South China Sea
throughout its life with MSW estimated by PAGASA to have been 30 kts.
A track for Gening is included in the companion tropical cyclone tracks
file, courtesy of Michael V. Padua.
Typhoon Maggie/Etang (TC-06W / TY 9903)
1 - 8 June
----------------------------------------
The disturbance which eventually developed into Typhoon Maggie was
first mentioned by JTWC in their Tropical Weather Outlook at 0600 UTC
on 27 May. A broad area of scattered convection with no discernible
rotation was located east of the Philippines and west of Palau. By
the 29th there was still no evidence of a circulation--the convection
was being maintained by cross-equatorial southwesterlies merging with
tropical easterlies. A couple of days later deep convection was
increasing, outflow was good and the system was in a region of weak
vertical shear. At 0000 UTC on 1 Jun PAGASA and JMA classified the
system as a tropical depression and initiated advisories with PAGASA
naming the depression Etang. Tropical Depression Etang was located
about 275 nm northwest of Palau with MSW (10-min) estimated at 30 kts.
Interestingly, JTWC only issued a Formation Alert at 0000 UTC and
did not initiate depression warnings until 0600 UTC, and then with
the MSW estimated at only 25 kts (1-min) (even though the Remarks
section in the warning indicated some synoptic observations in the
area of winds to 30 kts).
Dvorak T-numbers had reached 3.0 by 02/0000 UTC so JTWC upgraded
the depression to Tropical Storm Maggie with 45-kt MSW. Maggie/Etang
initially moved on a general north-northwesterly course as it was
steered by a subtropical ridge to its east. JTWC upgraded the storm
to a typhoon at 1800 UTC on 2 Jun when it was located approximately
300 nm east of Catanduanes Island in the Philippines. (PAGASA did
not upgrade Maggie/Etang to a typhoon until 03/1800 UTC.) By 1200
UTC on 3 Jun the typhoon was beginning to move more west-northwestward
as a mid-level ridge to the north strengthened. JTWC upped the MSW
to 90 kts at 04/0000 UTC as satellite imagery revealed a completely
formed eyewall with an anticyclone centered directly over the typhoon.
Peak MSW of 105 kts was reached at 0000 UTC on 5 Jun when Maggie/
Etang was located about 125 nm east-northeast of Cabo Engano on the
northern tip of Luzon. During its most intense phase, Maggie's eye
ranged from about 8 to 20 nm in diameter. PAGASA's peak 10-min
MSW reached 85 kts--JMA's value was predictably lower, reaching only
75 kts. As pressures built to the north, the typhoon slowly turned
to more of a west-northwesterly, then westerly, course which carried
it through the Batan Islands and the Bashi Channel. The center
passed around 60 nm south of the southern tip of Taiwan shortly after
1800 UTC on 5 Jun. Interaction with Taiwan caused Maggie to begin
slowly weakening and the MSW had decreased to 80 kts when the center
reached the Chinese coast just south of Shantou (or about 125 nm east
of Hong Kong) around 06/1200 UTC.
Instead of moving directly inland, Maggie turned to a slight
west-southwesterly course and skimmed along the southern coast of
China. Still carried by JTWC as a minimal typhoon, the storm passed
a short distance north of Hong Kong around 2000 UTC. By 0000 UTC on
the 7th, visible and infrared satellite imagery indicated Maggie had
lost about all of its deep convection, and there were no synoptic
observations (that JTWC had available, at least) of winds any greater
than 30 kts, so the storm was downgraded from a typhoon to a tropical
depression and the last warning issued at 07/0300 UTC when Maggie
was located roughly 60 nm west of Hong Kong along the Chinese coast.
There was considerable disagreement regarding the intensity of
Maggie during its dissipating stages. At the time JTWC downgraded
the typhoon to a depression and dropped it, JMA and the Royal
Observatory of Hong Kong (HKO) still carried Maggie as a rather strong
tropical storm. HKO downgraded the system to a tropical depression
at 07/0600 UTC while JMA still reported the MSW at 50 kts. However,
by the time JMA downgraded Maggie to a depression and dropped it, HKO
re-instated the system as a minimal tropical storm with 40-kt winds,
presumably based upon some synoptic observations. The rejuvenated
Maggie was reported to be quasi-stationary off the coast of China
approximately 120 nm southwest of Hong Kong. The storm subsequently
began to move northwestward and inland, and the last HKO warning at
0600 UTC on 8 Jun placed the dissipating depression north of Wuzhou.
The only report of fatalities due to Maggie that I could locate was
a press report which indicated that two persons were killed in the
Philippines near the town of Santo Domingo in Albay province southeast
of Manila. The deaths were due to a landslide triggered by heavy
rains related to the typhoon.
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NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for June: 1 tropical depression **
1 tropical cyclone of gale intensity
** - classified as a depression only by IMD
NOTE: The tracking and intensity information for North Indian Ocean
Basin tropical cyclones is based primarily upon operational warnings
from the Joint Typhoon Warning Center of the U. S. Air Force and Navy
(JTWC) 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
WMO's RSMC for the basin.
The MSW are based on a 1-min 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 region,
both 10-min and 3-min average winds are employed, but IMD makes no
attempt to modify the Dvorak scale for estimating tropical cyclone
intensity; hence, a 1-min avg MSW is implied. In the North Indian
basin JTWC usually does not initiate warnings until a system is
well-organized and likely to attain tropical storm status within
48 hours.
North Indian Ocean Activity for June
------------------------------------
In contrast to June of 1998 when a disastrous tropical cyclone
caused over 1000 deaths in northwest India, the month of June this
year was relatively quiet. A short-lived weak tropical cyclone
formed in the extreme northern reaches of the Bay of Bengal near
Calcutta and quickly moved inland on 10 June. A few days later
another system formed farther south in the Bay of Bengal and was
classified as a deep depression by IMD. This system moved inland
around 1200 UTC on 17 June near Berhampur, or about 100 nm south-
southwest of Cuttack. A short track is given for this system in
the accompanying tropical cyclone tracks file.
Tropical Cyclone (TC-03B)
--------------------------
The third tropical cyclone of 1999 to form in the North Indian Ocean
basin and the second in the Bay of Bengal was a short-lived monsoon
depression type of tropical cyclone. A area of convection which had
formed in the northern Bay of Bengal was first mentioned by JTWC on
8 Jun. Convection slowly became better organized over the next couple
of days and a low-level circulation developed. Convection developed
explosively near the center on 10 Jun and JTWC issued the first warning
on the developing cyclone at 1200 UTC. The center was located just off
the west end of the mouths of the Ganges River, or about 100 nm south
of Calcutta. Steered by a subtropical ridge to the north, the system
moved west-northwestward and made landfall around 1500 UTC about 90 nm
southwest of Calcutta.
By 11/0000 UTC the cyclone was inland and weakening about 150 nm
west of Calcutta. The system was intensifying quickly at the time
the first warning was issued, and based upon an analysis of satellite
imagery, the MSW likely reached 40-45 kts around the time the cyclone
made landfall.
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SOUTH INDIAN OCEAN (SIO) - South Indian Ocean West of Longitude 90E
Activity for June: No tropical cyclones
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AUSTRALIAN REGION (AUG) - From Longitude 90E Eastward to Longitude 160E
Activity for June: No tropical cyclones
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SOUTHWEST PACIFIC (SWP) - South Pacific Ocean East of Longitude 160E
Activity for June: No tropical cyclones
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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 included in the July, 1998 summary.
I will include this glossary from time to time, primarily in "lean"
months without a lot of tropical cyclone activity to cover. But if
anyone missed receiving it and wishes to obtain a copy, send me an
e-mail privately and I'll forward them a copy.
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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
in the following manner:
(a) FTP to: hrd-type42.nhc.noaa.gov [140.90.176.206]
(b) Login as: anonymous
(c) For a password use your e-mail address
(d) Go to "data" subdirectory (Type: cd data)
(e) Set file type to ASCII (Type: ascii)
(f) Transfer file (Type: get remote_file_name local_file_name )
(The files will be named with an obvious nomenclature--using
June as an example: jun99.tracks)
(g) To exit FTP, type: quit
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. If anyone wishes to retrieve any of the previous summaries,
they may be downloaded from the aforementioned FTP site at HRD. The
summary files are catalogued with the nomenclature: jun99.sum, for
example.
Back issues can also be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Tom Berg, and Michael
Pitt):
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:
TROPICAL CYCLONE REPORTS AVAILABLE
I have discovered that JTWC now has available on its new website
the complete Annual Tropical Cyclone Report for 1997 (1996-1997 season
for the Southern Hemisphere). Also, tracks only for the 1998 tropical
cyclones are currently available.
The URL is:
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 1998 Atlantic and Eastern North Pacific
tropical cyclones; also, preliminary storm reports for all the 1998
Atlantic and Eastern North Pacific cyclones are now available.
The URL is:
Prepared by: Gary Padgett
E-mail: garyp@alaweb.com
Phone: 334-222-5327 (nights & weekends) / 850-882-2594 (weekdays)
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