Invest 96A: Tropical Cyclone Formation Alert. Tapah(18W): over the Sea of Japan

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WESTERN NORTH PACIFIC

TS TAPAH(18W)
As of 18:00 UTC Sep 22, 2019:
Location: 35.4°N 131.5°E
Maximum Winds: 55 kt ( 100km/h)
Gusts: 70 kt ( 130km/h)
Minimum Central Pressure: 980 mb
WDPN31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (TAPAH) WARNING NR
015//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 18W (TAPAH), LOCATED APPROXIMATELY 52 NM
NORTH-NORTHWEST OF SASEBO, JAPAN, HAS TRACKED NORTHEASTWARD AT 17
KNOTS OVER THE PAST SIX HOURS. TS 18W HAS COMMENCED EXTRA-TROPICAL
TRANSITION (ETT) AND IS ACCELERATING NORTHEASTWARD WITHIN THE
MIDLATITUDE SOUTHWESTERLIES. ADDITIONALLY, THE SYSTEM HAS A WEAK
FRONTAL STRUCTURE AS EVIDENCED IN SATELLITE IMAGERY AND THE 22/06Z
1000-500MB THICKNESS ANALYSIS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A BROAD LOW-LEVEL CIRCULATION (LLCC) WITH DEEP
CONVECTION SHEARED TO THE NORTHEAST DUE TO STRONG (35-40 KNOT)
SOUTHERLY VERTICAL WIND SHEAR (VWS). A 221241Z MHS 89GHZ COLOR
COMPOSITE MICROWAVE IMAGE SHOWS AN EXPOSED, DEFINED LLCC WITH
RAPIDLY ERODING DEEP CONVECTION OVER THE NORTHEAST QUADRANT. A
221127Z ASCAT-A IMAGE INDICATES 50-55 KNOT WINDS OVER THE NORTHWEST
QUADRANT, THEREFORE, THE CURRENT INTENSITY REMAINS ASSESSED AT 55
KNOTS. ENVIRONMENTAL CONDITIONS ARE GRADUALLY DEGRADING WITH THE
INCREASING VWS AND SLIGHTLY COOLER SST, HOWEVER, POLEWARD OUTFLOW
REMAINS ROBUST. TS 18W IS TRACKING NORTHEASTWARD AS IT RECURVES
AROUND THE NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE (STR)
LOCATED TO THE SOUTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 18W WILL CONTINUE TO RECURVE NORTHEASTWARD INTO THE SEA OF
JAPAN WITH INCREASING, HOSTILE VWS EXPECTED AND COOLER SST (LESS
THAN 24C). TS 18W WILL COMPLETE ETT BY TAU 24 AND CONTINUE TO
ACCELERATE NORTHEASTWARD TOWARD HOKKAIDO. THE SYSTEM IS FORECAST TO
REMAIN A STRONG COLD-CORE LOW WITH GALE-FORCE WINDS ANTICIPATED OVER
NORTHERN HONSHU. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT
THROUGH TAU 36, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK.//
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NORTH INDIAN

INVEST 96A
As of 12:00 UTC Sep 22, 2019:
Location: 20.4°N 68.1°E
Maximum Winds: 30 kt
Minimum Central Pressure: 1002 mb
WTIO21 PGTW 221330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 96A)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 20.2N 68.6E TO 20.4N 61.9E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 221300Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 20.4N 68.1E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 96A) PREVIOUSLY LOCATED
NEAR 19.2N 70.2E IS NOW LOCATED NEAR 20.4N 68.1E, APPROXIMATELY 560
NM EAST OF MASIRAH ISLAND, OMAN. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY AND A 221135Z 91GHZ SSMIS IMAGE DEPICT A
CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTIVE BANDING OVER THE WESTERN QUADRANT. A 220448Z ASCAT-B
IMAGE ALSO DEPICTS A WELL DEFINED CIRCULATION WITH 25 TO 30 KNOT
WINDS IN THE NORTHWEST QUADRANT. UPPER LEVEL ANALYSIS REVEALS 96A
HAS RELATIVELY WEAK UPPER LEVEL OUTFLOW, BUT IS MOVING INTO AN AREA
OF FAVORABLE VERTICAL WIND SHEAR OF 5-10 KNOTS. SEA SURFACE
TEMPERATURES ALSO REMAIN FAVORABLE AT 27-29 DEGREES CELSIUS. GLOBAL
MODELS ARE IN GOOD AGREEMENT THAT 96A WILL CONTINUE TO SLOWLY
CONSOLIDATE AND INTENSIFY WHILE TRACKING WESTWARD TOWARDS OMAN.
ADDITIONALLY, ECMWF SHOWS 96A REACHING SUSTAINED WINDS OF 35 KNOTS
BY TAU 30. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30
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 HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
231330Z.//
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