WPAC: INVEST 99W

[Hayabusa]

99W INVEST 250811 1800 26.3N 177.1E WPAC 15 0

[StormWeather]

99W INVEST 250811 1800 26.3N 177.1E WPAC 15 0

According to the models, this could cross the IDL. Interested to see if the CPHC takes note of it at all.

[Hayabusa]

Now low

ABPW10 PGTW 131330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/131330Z-140600ZAUG2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/130751ZAUG2025//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 13AUG25 0600Z, TYPHOON 16W (PODUL) WAS LOCATED NEAR 22.9N
120.6E, APPROXIMATELY 141 NM SOUTH- SOUTHWEST OF TAIPEI, TAIWAN, AND
HAD TRACKED NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. MAXIMUM
SUSTAINED SURFACE WINDS WERE ESTIMATED AT 75 KNOTS GUSTING TO 90
KNOTS. SEE REF A (WTPN32 PGTW 130900) FOR FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR 25.6N
178.2E, APPROXIMATELY 285 NM WEST-SOUTHWEST OF MIDWAY. THE SYSTEM IS
CURRENTLY CLASSIFIED AS A SUBTROPICAL CYCLONE, GENERALLY CHARACTERIZED
AS HAVING BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. ANIMATED
ENHANCED INFRARED SATELLITE IMAGERY DEPICTS AN EXTREMELY ELONGATED
CIRCULATION LOCATED ALONG THE SOUTHWESTERN END OF A WEAK FRONTAL BAND
AND A PARTIALLY EXPOSED LLCC TYPICAL OF A SUBTROPICAL SYSTEM. A
130946Z ASCAT-C PASS REVEALS WINDS OF UP TO 25 KNOTS OVER THE SOUTHERN
PERIPHERY OF THE LLCC, WITH WINDS ON THE EASTERN SIDE NOW WRAPPING
INTO THE LLCC, SEPARATING IT FROM THE FRONTAL BAND. ENVIRONMENTAL
ANALYSIS REVEALS UNFAVORABLE CONDITIONS FOR TROPICAL TRANSITION
DEFINED BY A DEEP LAYER OF DRY AIR BEING ADVECTED OVER THE
CIRCULATION, COOL (26-27C) SEA SURFACE TEMPERATURES AND LIGHT TO
MODERATE NORTHERLY SHEAR IMPARTED BY A VERY LARGE UPPER-LEVEL LOW
POSITIONED TO THE NORTH. GLOBAL MODELS ARE IN AGREEMENT THAT 99W WILL
CONTINUE TO TRACK NORTHEAST AND THEN NORTHWARD OVER THE NEXT 24-48
HOURS, WITH A BROAD AND ASYMMETRIC WIND FIELD POSITIONED WELL AWAY
FROM THE CENTER. 99W WILL MOVE UNDER THE UPPER-LEVEL LOW WITHIN THE
NEXT 36 HOURS AND TRANSITION TO A COLD-CORE LOW. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. FOR HAZARDS AND WARNINGS,
REFERENCE THE FLEET WEATHER CENTER SAN DIEGO HIGH WINDS AND SEAS
PRODUCT OR REFER TO LOCAL WMO DESIGNATED FORECAST AUTHORITY. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS LOW.
(2) NO OTHER SUBTROPICAL SYSTEMS.
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 AREA IN PARA 1.C.1 AS A LOW//
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