WPAC: INVEST 99W

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99W INVEST 250915 0600 12.7N 126.8E WPAC 15 0

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Models suddenly want to develop this in the latest runs

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JMA 48hr forecast makes it a TD

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Latest GFS makes it an STS while traversing Extreme Northern Luzon

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Now low

ABPW10 PGTW 151200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/151200Z-160600ZSEP2025//
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 98W) PREVIOUSLY LOCATED NEAR
12.0N 117.9E IS NOW LOCATED NEAR 12.5N 116.3E, APPROXIMATELY 515 NM
EAST-SOUTHEAST OF DA NANG, VIETNAM. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) DEPICTS A POORLY DEFINED LOW-LEVEL CIRCULATION WITH
FLARING CONVECTION IN THE NORTHERN AND WESTERN PERIPHERIES. A 150217Z
METOP-C ASCAT PASS REVEALED A BROAD LOW LEVEL CIRCULATION WITH 10-15
KT WINDS WRAPPING FROM THE NORTHERN PORTION OF THE SYSTEM.
ENVIRONMENTAL ANALYSIS INDICATES MARGINALLY FAVORABLE CONDITIONS FOR
DEVELOPMENT WITH LOW VERTICAL WIND SHEAR (5-10 KTS), AND WARM (29-30
C) SEA SURFACE TEMPERATURES, OFFSET BY WEAK EQUATORWARD OUTFLOW ALOFT
AND THE BROAD NATURE OF THE WIND FIELD. GLOBAL DETERMINISTIC MODELS
ARE IN AGREEMENT THAT 98W WILL PROPAGATE NORTHWESTWARD THROUGH THE
SOUTH CHINA SEA WITH LITTLE DEVELOPMENT. ENSEMBLE MODELS ARE ALSO IN
AGREEMENT ON A NORTHWESTWARD TRACK OVER THE NEXT 24 HOURS WITH ECENS
BEING MORE AGGRESSIVE WITH THE INTENSITY OF THE SYSTEM. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO 18 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
REMAINS LOW.
(2) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR 13.7N
125.2E, APPROXIMATELY 90 NM EAST-NORTHEAST OF LEGAZPI. ANIMATED
ENHANCED INFRARED IMAGERY (EIR) DEPICTS A FULLY EXPOSED LOW LEVEL
CIRCULATION WITH SLIGHT CONVECTION JUST SOUTH OF THE CENTER. 99W
CURRENTLY SITS WITHIN A MUCH BROADER OVERALL AREA OF CYCLONIC TURNING
THROUGHOUT THE PHILIPPINES SEA. ENVIRONMENTAL ANALYSIS INDICATES A
MODERATELY FAVORABLE ENVIRONMENT WITH WARM (30 C) SEA SURFACE
TEMPERATURES, MODERATE EQUATORWARD OUTFLOW ALOFT, AND LOW (10-15 KTS)
VERTICAL WIND SHEAR IMPACTING THE SYSTEM FROM THE NORTHWEST. GLOBAL
DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE IS IN GOOD AGREEMENT ON A
NORTH-NORTHWESTWARD TRACK AS 99W CONTINUES TO INTENSIFY ALONG THE
COAST OF LUZON. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO
18 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 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: 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.(2).//
NNNN

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06z eps

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12z, some ensemble showing sub 900mb on future 90W