WPAC: BAILU - Post-Tropical

[Hayabusa]

TROPICAL DEPRESSION 996 HPA AT 26N 130E ENE SLOWLY.

93W INVEST 250731 0600 25.3N 131.1E WPAC 15 0

[Hayabusa]

ABPW10 PGTW 312200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/312200ZJUL2025-010600ZAUG2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/311951ZJUL2025//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 31JUL25 1800Z, TROPICAL STORM 12W (KROSA) WAS LOCATED
NEAR 31.6N 142.0E, APPROXIMATELY 250 NM SOUTH-SOUTHEAST OF YOKOSUKA,
JAPAN, AND HAD TRACKED NORTH- NORTHWESTWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 45 KNOTS
GUSTING TO 55 KNOTS. SEE REF A (WTPN31 PGTW 312100) FOR FURTHER
DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 93W) HAS PERSISTED NEAR 25.9N
131.6E, APPROXIMATELY 209 NM EAST OF OKINAWA, JAPAN. ANIMATED ENHANCED
INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD, POORLY-ORGANIZED LOW
LEVEL CIRCULATION CENTER (LLCC) WITH CYCLING DEEP CONVECTION BUILDING
NEAR THE CENTER. A 311148Z ASCAT METOP-B PASS SUPPORTING THE EIR
INDICATES A BROAD LLCC WITH SUSTAINED WINDS OF 15-20 KNOTS OVER THE
WESTERN QUADRANT. ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY
FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW TO MODERATE VERTICAL
WIND SHEAR (VWS) OF 15-20 KNOTS, GOOD POLEWARD UPPER-LEVEL OUTFLOW AND
WARM SEA SURFACE TEMPERATURES (SST) OF 28-29C. NUMERICAL MODELS
INDICATE SLOW DEVELOPMENT OF THIS SYSTEM AS IT TRACKS EASTWARD AND
NORTHEASTWARD OVER THE NEXT 24 TO 48 HOURS. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 13 TO 18 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 999 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.
3. JUSTIFICATION FOR REISSUE: ADDED LOW AREA IN PARA. 1.B.(1).//
NNNN

[cycloneye]

JMA at TD.

TD a
Issued at 2025/08/01 01:20 UTC
Analysis at 08/01 00 UTC
Grade TD
Scale -
Intensity -
Center position N25°20′ (25.3°)
E132°10′ (132.2°)
Direction and speed of movement E 15 km/h (9 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

[Hayabusa]

ABPW10 PGTW 011230
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED 011230Z-021230ZAUG2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/010751ZAUG2025//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 01AUG25 0600Z, TROPICAL STORM 12W (KROSA) WAS LOCATED NEAR
33.7N 141.3E, APPROXIMATELY 124 NM SOUTHEAST OF YOKOSUKA, JAPAN, AND HAD
TRACKED NORTHWARD AT 10 KNOTS OVER THE PAST SIX HOURS. MAXIMUM SUSTAINED
SURFACE WINDS WERE ESTIMATED AT 55 KNOTS GUSTING TO 70 KNOTS. SEE REF A
(WTPN31 PGTW 010900) FOR FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED NEAR
25.5N 134.1E IS NOW LOCATED NEAR 26.3N 135.1E, APPROXIMATELY 395 NM EAST
OF KADENA. ANIMATED MULTISPECTRAL IMAGERY (MSI) DEPICTS AN ELONGATED
AREA OF FLARING CONVECTION. A PARTIAL 010502Z ASCAT-B PASS REVEALS AN
ASYMMETRIC WEAK WIND FIELD OF 15-20 KNOT WINDS ALONG THE SOUTHERN
PERIPHERY DUE TO THE ENHANCED MONSOONAL FLOW. ENVIRONMENTAL ANALYSIS
REVEALS A MARGINAL CONDITIONS FOR DEVELOPMENT WITH LOW TO MODERATE
VERTICAL WIND SHEAR, MODERATE UPPER-LEVEL DIVERGENCE AND POLEWARD
OUTFLOW, AND WARM (28-29C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE
IN MODERATE AGREEMENT THAT INVEST 93W WILL DEVELOP WHILE TRACKING
NORTHEASTWARD IN 24-36 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO
BE NEAR 997 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.

[cycloneye]

[StormWeather]

https://i.imgur.com/FY4adWK.gif

Kay then, was not expecting this to be upgraded so quickly.

[sasha_B]

This is now TS Thirteen per JTWC; JMA still has it as a tropical depression.

13W THIRTEEN 250802 1800 31.0N 140.5E WPAC 35 997

[cycloneye]

JMA upgrades to TS Bailu.

TROPICAL STORM 2510 BAILU (2510) UPGRADED FROM TROPICAL DEPRESSION
996 HPA
AT 33.2N 140.9E SEA EAST OF JAPAN MOVING NORTHNORTHEAST 16 KNOTS.
POSITION FAIR.
MAX WINDS 35 KNOTS NEAR CENTER.

[wxman57]

JMA is still calling this extratropical low a TS. It's not officially "post-tropical".

[Hayabusa]

It's now an ET low from JMA's 00z