WPAC: AMPIL - Post-Tropical

[Hayabusa]

91W.INVEST

91W INVEST 240801 1200 27.0N 142.0E WPAC 15 0

[Hayabusa]

12Z

[Hayabusa]

Now low, interesting to watch how will the monsoon gyre evolves

ABPW10 PGTW 030600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/030600Z-040600ZAUG2024//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 91W) HAS PERSISTED NEAR 25.1N
137.4E, APPROXIMATELY 527 NM EAST OF KADENA AB. THE MONSOON GYRE EVENT
WHICH WAS PREDICTED LAST WEEK, HAS STARTED TO FORM IN THE NORTHERN
PHILIPPINE SEA, AFTER A MID-LATITUDE LOW PRESSURE AREA MOVED SOUTH OF
JAPAN EARLIER IN THE WEEK AND HAS DIVED SOUTHWARD, WHILE BECOMING MORE
TROPICAL IN NATURE. INVEST 91W HAS BEEN REPOSITIONED FROM ITS EARLIER
POSITION IN THE CENTROID OF THE LARGER ROTATION, TO TRACK THE LOW LEVEL
CIRCULATION CENTER (LLCC), WHICH IS THE ANCHOR POINT OF THE MONSOON GYRE
AND HAS BECOME BETTER ORGANIZED. INVEST 91W ITSELF IS EXPECTED TO TRACK
TOWARDS THE WEST-SOUTHWEST OVER THE NEXT FEW DAYS, BUT NO SIGNIFICANT
DEVELOPMENT IS EXPECTED, AS IT REMAINS THE ANCHOR POINT OF THE MONSOON
GYRE AND THUS NOT A TROPICAL CYCLONE. SOME ELEVATED WINDS ARE POSSIBLE,
ESPECIALLY ON THE WEST SIDE OF THE CIRCULATION, DUE TO GRADIENT PACKING,
BUT OTHERWISE 91W IS NOT EXPECTED TO POSE A SIGNIFICANT RISK TO ASSETS
AT THIS TIME. THE OVERALL GYRE CIRCULATION IS QUITE LARGE, SPANNING OUT
TO 600NM OR MORE (BASED ON THE RADIUS OF THE OUTER MOST CLOSED ISOBAR).
OVER THE NEXT WEEK OR TWO, THIS GYRE WILL CONTINUOUSLY PUMP OUT
ASYMMETRICAL CIRCULATIONS ALONG THE SOUTHEASTERN AND EASTERN PERIPHERY
IN A BAND OF ELEVATED, NEAR GALE FORCE WINDS. ANY OF THESE SMALL
CIRCULATIONS COULD REACH WARNING CRITERIA BEFORE WRAPPING UP AND AROUND
THE NORTHERN SIDE OF THE GYRE. MULTIPLE INVEST AREAS WILL POP-UP AND
DISAPPEAR DURING THIS EVENT, BUT DUE TO POOR PERFORMANCE OF THE MODELS
IN THIS SCENARIO, JTWC WILL BE IN A MORE REACTIVE MODE, OPENING AND
CLOSING INVESTS AS THE AVAILABLE DATA REVEALS THEIR EXISTENCE. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 22 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
IS LOW.
(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]

Remains low

ABPW10 PGTW 040600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/040600Z-050600ZAUG2024//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR
25.1N 137.4E IS NOW LOCATED NEAR 24.0N 134.8E, APPROXIMATELY 406 NM
EAST-SOUTHEAST OF KADENA AB. THE MONSOON GYRE EVENT IS NOW FIRMLY
ENTRENCHED ACROSS THE NORTHERN PHILIPPINE SEA, WITH INVEST 91W BEING
THE ANCHOR POINT OF A VERY LARGE CYCLONIC ROTATION, WITH A DIAMETER
NOW EXCEEDING 1400NM. INVEST 91W IS TRACKING TOWARDS THE WEST
SOUTHWEST AND WILL CONTINUE TO DO SO OVER THE NEXT FEW DAYS, BUT NO
SIGNIFICANT DEVELOPMENT IS EXPECTED AT THIS TIME. SOME ELEVATED WINDS
ARE POSSIBLE, ESPECIALLY ON THE WEST SIDE OF THE CIRCULATION, AND THE
PRESENCE OF INVEST 93W ROUGHLY 40NM NORTH OF 91W IS RACING DOWN FROM
THE NORTH AND WILL OVER THE NEXT COUPLE OF DAYS MERGE INTO THE LARGE
PRESSURE FIELD ASSOCIATED WITH 91W. BUT OTHERWISE 91W IS NOT EXPECTED
TO POSE A SIGNIFICANT RISK TO ASSETS AT THIS TIME. OVER THE NEXT WEEK
OR TWO, THIS GYRE WILL CONTINUOUSLY PUMP OUT ASYMMETRICAL CIRCULATIONS
ALONG THE SOUTHEASTERN AND EASTERN PERIPHERY IN A BAND OF ELEVATED,
NEAR GALE FORCE WINDS, SUCH AS INVEST 92W CURRENTLY MOVING NORTHWARD
INTO THE FAR NORTHEASTERN CORNER OF THE GYRE CIRCULATION. ANY OF THE
NOW AND FUTURE SMALL CIRCULATIONS COULD REACH WARNING CRITERIA BEFORE
WRAPPING UP AND AROUND THE NORTHERN SIDE OF THE GYRE OR MERGING INTO
THE LARGER ANCHOR CIRCULATION. MULTIPLE INVEST AREAS WILL POP-UP AND
DISAPPEAR DURING THIS EVENT, BUT DUE TO POOR PERFORMANCE OF THE MODELS
IN THIS SCENARIO, JTWC WILL BE IN A MORE REACTIVE MODE, OPENING AND
CLOSING INVESTS AS THE AVAILABLE DATA REVEALS THEIR EXISTENCE. ACROSS
THE SPAN OF THE GYRE, THE ENVIRONMENT IS GENERALLY FAVORABLE WITH WARM
SSTS, GOOD OUTFLOW ALOFT AND RELATIVELY LOW SHEAR, BUT THE
ENVIRONMENTAL ASSESSMENT WILL VARY BASED ON THE EXACT POSITIONING OF
THE INVEST AREAS WITHIN THE GYRE. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 18 TO 22 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.
(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]

00Z JMA TD

WWJP27 RJTD 040000
WARNING AND SUMMARY 040000.
WARNING VALID 050000.
WARNING IS UPDATED EVERY 6 HOURS.
TROPICAL DEPRESSION 1002 HPA AT 24N 135E WSW 10 KT.

[Hayabusa]

Back to low and TD since 11/00Z

ABPW10 PGTW 111930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/111930Z-120600ZAUG2024//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/111351ZAUG2024//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 11AUG24 1200Z, TROPICAL STORM 06W (MARIA) WAS LOCATED
NEAR 37.8N 143.3E, APPROXIMATELY 184 NM SOUTH-SOUTHEAST OF MISAWA,
JAPAN, AND HAD TRACKED WEST-NORTHWESTWARD AT 05 KNOTS OVER THE PAST
SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 55 KNOTS
GUSTING TO 70 KNOTS. SEE REF A (WTPN31 PGTW 111500) FOR FURTHER
DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 91W) HAS PERSISTED NEAR 22.1N
135.6E, APPROXIMATELY 425 NM EAST-SOUTHEAST OF KADENA. ANIMATED
ENHANCED INFRARED SATELLITE IMAGERY AND A 111708Z AMSR2 89GHZ
SATELLITE IMAGE DEPICTS AN AREA OF FLARING CONVECTION AND FORMATIVE
CLOUD BANDING WRAPPING INTO A WEAKLY DEFINED LOW LEVEL CIRCULATION
CENTER (LLCC). ENVIRONMENTAL ANALYSIS REVEALS AN AREA THAT IS
MARGINALLY FAVORABLE FOR DEVELOPMENT WITH WARM (29-30C) SST, LOW
VERTICAL WIND SHEAR (10-15KTS), AND GOOD EQUATORWARD OUTFLOW ALOFT.
MODELS ARE IN GOOD AGREEMENT THAT 91W WILL CONTINUE TO TRACK
NORTHEASTWARD OVER THE NEXT 48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 13 TO 18 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.
(3) NO OTHER SUSPECT AREAS.
C. SUBTROPICAL SYSTEM SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 95W) PREVIOUSLY LOCATED NEAR
27.1N 154.9E IS NOW LOCATED NEAR 27.8N 155.2E, APPROXIMATELY 910 NM
EAST-SOUTHEAST OF YOKOSUKA. THE SYSTEM IS CURRENTLY CLASSIFIED AS A
SUBTROPICAL CYCLONE, GENERALLY CHARACTERIZED AS HAVING BOTH TROPICAL
AND MIDLATITUDE CYCLONE FEATURES. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS LOW-LEVEL CLOUD LINES WRAPPING INTO A FULLY-EXPOSED
LOW-LEVEL CIRCULATION, WITH ISOLATED DEEP CONVECTION SHEARED TO THE
EAST. A 110320Z AMSR2 WINDSPEED IMAGE AND A 110006Z ASCAT-C IMAGE
REVEAL A HIGHLY ASYMMETRIC WIND FIELD WITH 30-35 KNOT WINDS DISPLACED
WELL TO THE SOUTH AND EAST OF THE CENTER. AS EVIDENT IN THE TOTAL
PRECIPITABLE WATER IMAGERY, 95W IS LOCATED ALONG THE EASTERN PERIPHERY
OF THE MONSOON GYRE, WITH A HIGHLY ASYMMETRIC, EXTENSIVE REGION OF
DEEP MOISTURE EXTENDING WESTWARD TO 125E. GLOBAL MODELS INDICATE THE
SYSTEM WILL TRACK POLEWARD UNDER THE STRONG UPPER-LEVEL LOW OVER THE
NEXT TWO DAYS WITH GRADUAL WEAKENING. FOR HAZARDS AND WARNINGS,
REFERENCE THE FLEET WEATHER CENTER SAN DIEGO HIGH WINDS AND SEAS
PRODUCT OR REFER TO LOCAL WMO DESIGNATED FORECAST AUTHORITY. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 30 TO 35 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 995 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
REMAINS MEDIUM.
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

WWJP27 RJTD 111800
WARNING AND SUMMARY 111800.
WARNING VALID 121800.
WARNING IS UPDATED EVERY 6 HOURS.
TROPICAL DEPRESSION 1000 HPA AT 22N 135E EAST SLOWLY.

[Hayabusa]

JMA

TD c
Issued at 2024/08/12 01:30 UTC
Analysis at 08/12 00 UTC
Grade TD
Scale -
Intensity -
Center position N22°20′ (22.3°)
E135°50′ (135.8°)
Direction and speed of movement E Slow
Central pressure 1002 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 08/13 00 UTC
Grade TS
Intensity -
Center position of probability circle N24°35′ (24.6°)
E138°30′ (138.5°)
Direction and speed of movement NE 20 km/h (10 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 08/14 00 UTC
Grade TS
Intensity -
Center position of probability circle N26°35′ (26.6°)
E140°30′ (140.5°)
Direction and speed of movement NE 15 km/h (7 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 200 km (110 NM)
Forecast for 08/15 00 UTC
Grade STS
Intensity -
Center position of probability circle N29°10′ (29.2°)
E140°50′ (140.8°)
Direction and speed of movement N 15 km/h (7 kt)
Central pressure 990 hPa
Maximum sustained wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 260 km (140 NM)
Forecast for 08/16 00 UTC
Grade STS
Intensity -
Center position of probability circle N33°35′ (33.6°)
E140°30′ (140.5°)
Direction and speed of movement N 20 km/h (11 kt)
Central pressure 985 hPa
Maximum sustained wind speed near center 30 m/s (55 kt)
Maximum wind gust speed 40 m/s (80 kt)
Radius of probability circle 330 km (180 NM)
Radius of storm warning area 390 km (210 NM)
Forecast for 08/17 00 UTC
Grade STS
Intensity -
Center position of probability circle N38°25′ (38.4°)
E143°35′ (143.6°)
Direction and speed of movement NNE 25 km/h (14 kt)
Central pressure 985 hPa
Maximum sustained wind speed near center 30 m/s (55 kt)
Maximum wind gust speed 40 m/s (80 kt)
Radius of probability circle 440 km (240 NM)
Radius of storm warning area 500 km (270 NM)

[Hurricane2022]

TD 08W (Future Typhoon Ampil) is likely set to make history if this forecast is right

[ElectricStorm]

Yeah this could be the real deal, HAFS-A has 100kts shortly before landfall. HWRF still running but has a Cat 1 already in less than 40 hours.

[Hayabusa]

Now Ampil since 1218Z

T2407(Ampil)
Issued at 2024/08/12 22:00 UTC
Analysis at 08/12 21 UTC
Grade TS
Scale -
Intensity -
Center position N23°55′ (23.9°)
E137°20′ (137.3°)
Direction and speed of movement ENE 10 km/h (6 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 30-kt wind area E220 km (120 NM)
W165 km (90 NM)

[ElectricStorm]

12z HAFS-A has a Cat 5 SE of Tokyo 140kts/923mb

I highly doubt that happens, has there ever been a Cat 5 that far north?

HWRF still running but already at 105kts at hour 54

[ElectricStorm]

Trying to clear an eye out already although it looks like there's a bit of dry air it needs to mix out. Looks well on its way to becoming a major which seems relatively rare for a storm this far north. Current forecasted 105kt peak may end up being too low at this rate.

[dexterlabio]

Is this still only a TS?

[Hurricane2022]

JMA still at 60 kt/975 but the JTWC has it as a 75 kt Typhoon.

[ElectricStorm]

08W AMPIL 240815 0000 29.7N 141.2E WPAC 85 967

Cat 2 already, well ahead of the forecast

[Kingarabian]

Tokyo needs to keep an eye out for this.

[Hurricane2022]

Beautiful donut. It could be a strong major typhoon now but i'm not very sure about that, since Nigel '23 looked almost the same but recon found only a peak intensity of 85 kt/970. I think that the 95/952 estimate from JTWC is reasonable.

[doomhaMwx]

Drifting buoy "5802056" entered the edge of the eye/eyewall and recorded a min SLP of 966 mb at ~10Z today (966.5 mb at ~11Z).


 https://x.com/doomhaMwx/status/1824116490385441149

[ElectricStorm]

08W AMPIL 240815 1800 32.5N 140.8E WPAC 100 951

[Teban54]