WPAC: PULASAN - Tropical Storm

[Hayabusa]

97W INVEST 240914 1200 14.5N 144.2E WPAC 15 0

[Hayabusa]

Now low

ABPW10 PGTW 141930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED 141930Z-150600ZSEP2024//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/141351ZSEP2024//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 14SEP24 0000Z, TYPHOON 14W (BEBINCA) WAS LOCATED
NEAR 26.3N 131.4E, APPROXIMATELY 194 NM EAST OF KADENA AB, AND HAD
TRACKED NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. MAXIMUM
SUSTAINED SURFACE WINDS WERE ESTIMATED AT 50 KNOTS GUSTING TO 65 KNOTS.
SEE REF A (WTPN31 PGTW 141500) FOR FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
(1) AN AREA OF CONVECTION (INVEST 97W) HAS PERSISTED NEAR
13.0N 143.1E, APPROXIMATELY 106 NM WEST-SOUTHWEST OF ANDERSEN AFB, GUAM.
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A BROAD, ELONGATED
AREA OF TURNING OBSCURED BY FLARING, DISORGANIZED, FLARING DEEP
CONVECTION. THE POSITION IS BASED ON THE CENTROID OF THE BROAD
CIRCULATION AND EXTRAPOLATED FROM SURFACE WIND OBSERVATIONS ON GUAM.
ANALYSIS INDICATES 97W IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT IN A
NARROW ZONE WITH LOW TO MODERATE (10-20 KNOT) VWS, STRONG DIVERGENCE
ALOFT AND VERY WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS
INDICATE THAT 97W WILL BECOME ONE OF TWO VORTICES ALONG THE EASTERN
PERIPHERY OF AN EVOLVING MONSOON DEPRESSION (MD) THAT EXTENDS FROM THE
NORTHERN PHILIPPINE SEA INTO THE SOUTH CHINA SEA. 97W WILL GENERALLY
TRACK NORTH- TO NORTHWESTWARD ALONG THE PERIMETER OF THE MD. ALTHOUGH
CONDITIONS ARE FAVORABLE, THE LACK OF A DISTINCT, CONSOLIDATED LOW LEVEL
CIRCULATION CENTER AT THIS TIME WILL SERVE TO LIMIT THE POTENTIAL
DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS LOW.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: ADDED LOW AREA IN PARA. 1.B.(1).//
NNNN

[Hayabusa]

12z

[Hayabusa]

Up to medium

ABPW10 PGTW 150600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/150600Z-160600ZSEP2024//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/150151ZSEP2024//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 15SEP24 0000Z, TYPHOON 14W (BEBINCA) WAS LOCATED NEAR
29.7N 127.1E, APPROXIMATELY 303 NM EAST-SOUTHEAST OF SHANGHAI, CHINA,
AND HAD TRACKED NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS.
MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 65 KNOTS GUSTING TO
80 KNOTS. SEE REF A (WTPN31 PGTW 150300) FOR FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 97W) PREVIOUSLY LOCATED NEAR
13.0N 143.1E IS NOW LOCATED NEAR 14.0N 143.0E, APPROXIMATELY 105 NM
WEST-NORTHWEST OF GUAM. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
A BELT OF SCATTERED CONVECTION FLARING ACROSS THE PHILIPPINE SEA, FROM
THE PHILIPPINES TO THE SOUTHERN MARIANAS. EXPOSED LOW LEVEL CLOUDS NEAR
GUAM ARE DRIFTING CYCLONICALLY, CONSISTENT WITH SURFACE WEATHER
OBSERVATIONS FROM GUAM AND SCATTEROMETRY DATA DEPICTING BROAD CYCLONIC
TURNING. EXISTING DEEP CONVECTION IS CHAOTIC AND STRONGLY SHEARED BY
NORTHEASTERLY WINDS IN THE UPPER LEVELS. A 150347Z AMSR2 IMAGE FURTHER
REVEALS WEAK AND VERY FRAGMENTED BANDING, WITH NOTHING WELL DEFINED AT
PRESENT. HOWEVER, GLOBAL MODELS INDICATE IN THIS VICINITY AN AREA OF
LOW PRESSURE BECOMING CONSOLIDATED IMMEDIATELY WEST OF THE MARIANAS AS
A WESTERLY WIND BURST CAUSES SPIKING VORTICITY VALUES ALONG THE
CONVECTIVELY ACTIVE MONSOON TROUGH. MODEL GUIDANCE VARIES IN HOW
QUICKLY OR DEEPLY TO DEVELOP THE AREA OF CONCENTRATED PRESSURE FALLS,
BUT THERE IS CONSISTENTLY FAIR AGREEMENT THAT IT WILL TRACK AWAY FROM
THE MARIANAS AND HEAD GENERALLY NORTH AND EVENTUALLY NORTHWESTWARD
UNDER THE STEERING INFLUENCES OF A SUBTROPICAL RIDGE. CURRENT GUIDANCE
SUGGESTS THE SYSTEM MAY BECOME PART OF A MUCH LARGER REGION OF BROAD
CYCLONIC TROUGHING. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15
TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.
(2) NO OTHER SUSPECT AREAS.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
NNNN

[Hayabusa]

JMA TC warning similar track to Bebinca...

TD b
Issued at 2024/09/15 07:30 UTC
Analysis at 09/15 06 UTC
Grade TD
Scale -
Intensity -
Center position N11°55′ (11.9°)
E144°00′ (144.0°)
Direction and speed of movement Almost stationary
Central pressure 1000 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 09/15 18 UTC
Grade TD
Intensity -
Center position of probability circle N14°20′ (14.3°)
E144°35′ (144.6°)
Direction and speed of movement N 20 km/h (10 kt)
Central pressure 1000 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Radius of probability circle 100 km (55 NM)
Forecast for 09/16 06 UTC
Grade TS
Intensity -
Center position of probability circle N16°00′ (16.0°)
E144°00′ (144.0°)
Direction and speed of movement NNW 20 km/h (11 kt)
Central pressure 998 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 130 km (70 NM)
Forecast for 09/17 06 UTC
Grade TS
Intensity -
Center position of probability circle N22°05′ (22.1°)
E137°30′ (137.5°)
Direction and speed of movement WNW 40 km/h (22 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 200 km (110 NM)
Forecast for 09/18 06 UTC
Grade TS
Intensity -
Center position of probability circle N26°10′ (26.2°)
E129°25′ (129.4°)
Direction and speed of movement WNW 40 km/h (21 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 260 km (140 NM)
Forecast for 09/19 06 UTC
Grade TS
Intensity -
Center position of probability circle N28°30′ (28.5°)
E122°50′ (122.8°)
Direction and speed of movement WNW 30 km/h (16 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 330 km (180 NM)
Forecast for 09/20 06 UTC
Grade TD
Intensity -
Center position of probability circle N26°20′ (26.3°)
E117°40′ (117.7°)
Direction and speed of movement WSW 25 km/h (13 kt)
Central pressure 998 hPa
Radius of probability circle 440 km (240 NM)

[Hayabusa]

JMA upgrades to Pulasan

T2414(Pulasan)
Issued at 2024/09/15 13:25 UTC
Analysis at 09/15 12 UTC
Grade TS
Scale Large
Intensity -
Center position N13°30′ (13.5°)
E143°55′ (143.9°)
Direction and speed of movement N Slow
Central pressure 1002 hPa
Maximum wind speed 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of 30-kt wind area E800 km (425 NM)
W500 km (270 NM)
Forecast for 09/16 00 UTC
Grade TS
Intensity -
Center position of probability circle N14°55′ (14.9°)
E144°20′ (144.3°)
Direction and speed of movement NNE 15 km/h (7 kt)
Central pressure 1000 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 75 km (40 NM)
Forecast for 09/16 12 UTC
Grade TS
Intensity -
Center position of probability circle N17°35′ (17.6°)
E142°20′ (142.3°)
Direction and speed of movement NW 30 km/h (17 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 105 km (57 NM)
Forecast for 09/17 12 UTC
Grade TS
Intensity -
Center position of probability circle N22°50′ (22.8°)
E136°00′ (136.0°)
Direction and speed of movement NW 35 km/h (20 kt)
Central pressure 992 hPa
Maximum sustained wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 185 km (100 NM)
Forecast for 09/18 12 UTC
Grade TS
Intensity -
Center position of probability circle N26°35′ (26.6°)
E127°25′ (127.4°)
Direction and speed of movement WNW 40 km/h (22 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 260 km (140 NM)
Forecast for 09/19 12 UTC
Grade TS
Intensity -
Center position of probability circle N28°00′ (28.0°)
E120°30′ (120.5°)
Direction and speed of movement W 30 km/h (16 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 320 km (175 NM)
Forecast for 09/20 12 UTC
Grade TD
Intensity -
Center position of probability circle N28°20′ (28.3°)
E117°35′ (117.6°)
Direction and speed of movement W 10 km/h (6 kt)
Central pressure 998 hPa
Radius of probability circle 400 km (215 NM)

[doomhaMwx]

How is this a TC? Scatterometer data even indicates there are a couple of separate circulations in all that convection.

[Hayabusa]

Jtwc tcfa

[Hayabusa]

Up to 60 knots surprisingly despite its looks due to reasoning below...

WDPN32 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (PULASAN) WARNING NR
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 21.2N 134.7E
INITIAL INTENSITY: 60 KTS
GEOGRAPHIC REFERENCE: 494 NM SOUTHEAST OF KADENA AB
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 18 KTS
SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD
MONSOON DEPRESSION WITH SUBSIDENT DRY AIR REVEALING THE LOW-LEVEL
CIRCULATION CENTER (LLCC). A BAND OF ENHANCED WIND WRAPS AROUND THE
EASTERN PERIPHERY OF TROPICAL STORM (TS) 15W WITH ASSOCIATED DEEP
CONVECTION WHILE THE CENTER REMAINS CLEAR AND FED WITH DRY AIR FROM
THE TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL LOCATED TO THE
WEST. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
ON THE ANIMATED EIR DEPICTING A BROAD AREA OF TURNING AND A CLEAR
CENTER OF DRY AIR, MAKING PINNING DOWN A CENTER LOCATION DIFFICULT.
WHILE FNMOC IS EXPERIENCING A SYSTEM DEGRADATION, DATA FOR TS 15W
HAS BEEN SPARSE UNTIL A 170857Z RCM-2 SYNTHETIC APERTURE RADAR
(SAR) PASS REVEALED MUCH STRONGER WINDS (60-70KTS) THAN ASSESSED IN
THE PREVIOUS WARNING. THE ELEVATED INTENSITY WAS FURTHER SUPPORTED
BY A SIMILARLY TIMED 170911Z SMOS PASS DISCLOSING DATA ABOVE 55KTS,
NAILING DOWN THE INTENSITY ASSESSMENT TO BE 60KTS. NEVERTHELESS,
BOTH IMAGES WERE PARTIAL PASSES DUE TO THE LARGE DIAMETER OF THE
SYSTEM WITH A MAXIMUM 35KT WIND RADIUS OF 310NM. THE INITIAL
INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AFOREMENTIONED SMOS AND SAR PARTIAL IMAGERY AND THE INABILITY TO
CAPTURE THE INTENSITY THROUGHOUT THE ENTIRE SYSTEM.

INITIAL WIND RADII BASIS: SAR DATA

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T2.0 - 30 KTS
RCTP: T1.5 - 25 KTS
KNES: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE INTENSITY FORECAST HAS CHANGED
SIGNIFICANTLY SINCE THE PREVIOUS WARNING DUE TO UPDATED WIND SPEED
DATA FROM RCM-2 AT 170857Z THAT INDICATES WIND SPEEDS UP TO 60KTS
IN THE NORTHERN AND EASTERN PERIPHERY OF THE SYSTEM. AS A RESULT,
THE OVERALL TRACK INTENSITY IS HIGHER UNTIL LANDFALL, WHEN RAPID
WEAKENING WILL OCCUR. SINCE THE CURRENT INTENSITY IS HIGHEST IN THE
NORTHERN AND NORTHWESTERN PERIPHERY OF THE SYSTEM, THE IMPACTS TO
OKINAWA MAY BE GREATER THAN IN THE PREVIOUS WARNING AS THE SYSTEM
TRACKS SOUTH OF THE ISLAND.

FORECAST DISCUSSION: TS 15W CONTINUES TO MAINTAIN THE
CHARACTERISTICS OF A MONSOON DEPRESSION GIVEN THE AFOREMENTIONED
BROAD CIRCULATION AND ENHANCED WINDS DISPLACED 145NM-310NM FROM
CENTER. WARNINGS CONTINUE DUE TO THE POTENTIAL IMPACTS TS 15W MAY
BRING TO OKINAWA WITHIN 24 HOURS. TS 15W IS FORECAST TO TRACK
NORTHWESTWARD WHILE DRIVEN BY A STR TO THE NORTH. THE TRACK SPEED
IS EXPECTED TO BE ENHANCED ABOVE THE TYPICAL NATURE FOR A TROPICAL
SYSTEM DUE TO CONSTRUCTIVE INTERFERENCE BETWEEN THE STR AND A TUTT
CELL TO THE WEST DRIVING THE SYSTEM FORWARD. THE SYSTEM IS EXPECTED
TO TRACK APPROXIMATELY 50NM SOUTH OF OKINAWA WITHIN 24 HOURS, BUT
GIVEN THE LARGE NATURE OF THE MONSOON DEPRESSION THE WIND FIELD
WILL BE DISPLACED FAR FROM CENTER AND IS MORE LIKELY TO IMPACT
OKINAWA WHILE PASSING SOUTH. GIVEN THE CURRENT 145NM RADIUS OF
MAXIMUM WIND, IF THE SYSTEM WERE TO DEVIATE FARTHER SOUTH, THE
INTENSITY MAY INCREASE. THROUGH THE FIRST 48 HOURS, THE SYSTEM WILL
GRADUALLY WEAKEN UNTIL MAKING LANDFALL. THE PRESSURE GRADIENT
BETWEEN THE STR TO THE NORTH AND THE MONSOON DEPRESSION WILL
DIMINISH, INITIATING THE PROGRESSIVE WEAKENING TREND. THE WEAKENING
WILL FURTHER AS THE TUTT CELL CONTINUES TO FEED CONTINENTAL DRY AIR
INTO THE SYSTEM AND VERTICAL WIND SHEAR INCREASES, WEARING AWAY AT
CONVECTIVE DEVELOPMENT. ONCE MAKING LANDFALL, THE SYSTEM WILL
RAPIDLY WEAKEN TO DISSIPATION BY TAU 96 DUE TO TOPOGRAPHIC
INTERACTION.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT AS THE SYSTEM TRACKS NORTHWESTWARD WITH A MAXIMUM
CROSS-TRACK SPREAD OF 100NM BY TAU 72, AND BIFURCATING VARIABLY BY
TAU 96 DUE TO RAPID WEAKENING AND DIFFICULTY FOR THE MODELS TO
TRACK THE WEAK AND ALREADY BROAD SYSTEM. THE INTENSITY GUIDANCE IS
UNRELIABLE GIVEN THE DIFFICULTY IN TRACKING THE CORE OF THE SYSTEM
AND THE DISLOCATED CIRCULATION CENTER. HAFS-A FORECASTS
INTENSIFICATION JUST ABOVE 60KTS FOR THE FIRST 36 HOURS WHILE HWRF
INDICATES RAPID WEAKENING WITH SPURIOUS INTENSIFICATION AT TAU 36
BEFORE MEETING THE SAME TREND OF WEAKENING AS HAFS-A.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: LOW
INTENSITY 72-120 HR: LOW//
NNNN

[Hayabusa]

79 kts at NE

[Hayabusa]

TY winds @ 995 mb

15W PULASAN 240917 1800 22.3N 133.4E WPAC 65 995

[Subtrop]

wow

WP, 15, 2024091718, , BEST, 0, 223N, 1334E, 65, 995, MD, 34, NEQ, 250, 310, 0, 180, 1000, 240, 135, 0, 0, W, 0, , 0, 0, PULASAN, M,
WP, 15, 2024091718, , BEST, 0, 223N, 1334E, 65, 995, MD, 50, NEQ, 100, 115, 0, 140, 1000, 240, 135, 0, 0, W, 0, , 0, 0, PULASAN, M,
WP, 15, 2024091718, , BEST, 0, 223N, 1334E, 65, 995, MD, 64, NEQ, 0, 0, 0, 135, 1000, 240, 135, 0, 0, W, 0, , 0, 0, PULASAN, M,

[ElectricStorm]

65kt monsoon depression? Why is it even classified if it isn't a TC?

[doomhaMwx]

65kt monsoon depression? Why is it even classified if it isn't a TC?

Probably because it's heading to a US military base (Okinawa). JTWC normally wouldn't issue warnings on a monsoon depression until it becomes a bonafide TD.

[doomhaMwx]

Peak intensity was lowered to 60 kts on the working best track.

15W PULASAN 240918 0000 23.4N 131.9E WPAC 55 998
15W PULASAN 240917 1800 22.3N 133.4E WPAC 55 995
15W PULASAN 240917 1200 21.3N 134.5E WPAC 60 996
15W PULASAN 240917 0600 20.1N 136.4E WPAC 45 996

[cycloneye]

 https://x.com/cyclonicwx/status/1836426929055887549