WTPN21 PGTW 222200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 21.5N 147.0E TO 26.0N 150.3E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 221800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 21.7N 147.1E. THE SYSTEM IS MOVING EASTWARD AT 10 KNOTS.
2. REMARKS: AN AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED 
NEAR 21.4N 144.9E IS NOW LOCATED NEAR 21.7N 144.7E, APPROXIMATELY 
366 NM EAST-SOUTHEAST OF IWO-TO. THE SYSTEM IS CURRENTLY CLASSIFIED 
AS A SUBTROPICAL STORM/DEPRESSION, GENERALLY CHARACTERIZED AS HAVING 
BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. ANIMATED ENHANCED 
INFRARED SATELLITE IMAGERY (EIR) AND A 221852Z SSMIS 91 GHZ 
MICROWAVE IMAGE DEPICT A LOW LEVEL CIRCULATION CENTER (LLCC) FORMING 
ALONG THE EASTERN EXTENT OF THE MONSOON TROUGH WITH DEEP CONVECTION 
OFFSET TO THE EASTERN AND SOUTHEASTERN PERIPHERIES. ENVIRONMENTAL 
ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT, WITH ROBUST 
EQUATORWARD OUTFLOW, LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), AND 
WARM (29-30C) SEA SURFACE TEMPERATURES (SST). THIS DISTURBANCE IS 
EXPECTED TO DEVELOP QUICKLY AS A SUBTROPICAL CYCLONE AND IS 
FORECASTED TO INTENSIFY AS IT TRACKS NORTHEASTWARD WITHIN A DEEP 
UPPER-LEVEL TROUGH WITH WEAK BAROCLINICITY. GLOBAL MODELS INDICATE 
THAT AS THE SYSTEM TRACKS TOWARD CENTRAL HONSHU, THE SYSTEM WILL 
TRANSITION TO A WARM-CORE TROPICAL SYSTEM EAST OF THE KANTO PLAIN. 
WHILE THE SYSTEM IS SUBTROPICAL, REFERENCE THE FLEET WEATHER CENTER 
SAN DIEGO HIGH WINDS AND SEAS PRODUCT OR REFER TO THE LOCAL WMO 
DESIGNATED FORECAST AUTHORITY FOR HAZARDS AND WARNINGS. MAXIMUM 
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 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 
232200Z.//
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