WTPN21 PGTW 222130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
110 NM EITHER SIDE OF A LINE FROM 19.9N 121.5E TO 15.9N 119.5E
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 20 TO 25 KNOTS. METSAT
IMAGERY AT 222130Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 19.4N 121.5E. THE SYSTEM IS MOVING WESTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED
NEAR 19.2N 121.8E IS NOW LOCATED NEAR 19.4N 121.5E, APPROXIMATELY
65 NM NORTH OF APARRI, PHILIPPINES. ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION 
(LLC) WITH PERSISTENT CENTRAL CONVECTION OVER THE CENTER. ANIMATED RADAR 
IMAGERY AND A 221941Z SSMIS 91GHZ MICROWAVE IMAGE DEPICT IMPROVED CURVED 
CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW LEVEL CIRCULATION CENTER 
(LLCC). RECENT OBSERVATIONS FROM CALAYAN, PHILIPPINES INDICATE A 
SIGNIFICANT 24-HOUR SLP DECREASE OF 7 MB FROM 1004MB TO 997MB WITH 
SUSTAINED SOUTHWESTERLY WINDS OF 12 KNOTS. ENVIRONMENTAL ANALYSIS 
REVEALS A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW VERTICAL WIND 
SHEAR (VWS) OF 5-10 KNOTS, GOOD EQUATORWARD UPPER-LEVEL OUTFLOW AND 
EASTWARD OUTFLOW, AND WARM SEA SURFACE TEMPERATURES (SST) OF 29-31C. 
DETERMINISTIC MODELS HAVE COME INTO BETTER ALIGNMENT SHOWING WINDS OF 
30-40 KNOTS WRAPPING AROUND THE LLC IN THE NEXT 24-36 HOURS. AVAILABLE 
MODEL GUIDANCE SHOWS A SOUTHWARD TRACK ALONG THE WESTERN COAST OF LUZON.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 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 
232130Z.//
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