WTPN21 PGTW 210800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 93W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 17.4N 127.7E TO 17.7N 122.9E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 210600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.4N 127.3E. THE SYSTEM IS MOVING WESTWARD AT 07 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED AT 17.5N 128.0E IS NOW LOCATED NEAR 17.4N 127.3E, APPROXIMATELY 535 NM SOUTH OF KADENA AB. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) LOCATED ON THE NORTHEASTERN EDGE OF AN AREA OF PERSISTENT DEEP CONVECTIVE ACTIVITY. THE LLCC HAS BEEN TUCKING IN AND OUT FROM UNDER THE CONVECTIVE CANOPY OVER THE PAST 12 HOURS AND HAS YET TO REMAIN ENSCONCED UNDER THE CONVECTION FOR LONG. HOWEVER, RECENT SCATTEROMETER DATA REVEALS THE LOW LEVEL CIRCULATION HAS TIGHTENED UP, AS EVIDENCED IN THE ANIMATED VISIBLE IMAGERY AS WELL, AND THE RATHER LARGE WIND FIELD HAS STRENGTHENED, WITH 20 TO 25 KNOT WINDS NOW PRESENT ACROSS THE MAJORITY OF THE CIRCULATION. THE ENVIRONMENT HAS IMPROVED SLIGHTLY, WITH THE SHEAR OVER TOP OF THE SYSTEM NOW ESTIMATED AROUND 15-20 KNOTS, DOWN ABOUT 5 KNOTS FROM THE PREVIOUS ANALYSIS, WHILE THE SYSTEM IS MOVING OVER VERY WARM, HIGH OHC WATERS PROVIDING AMPLE ENERGY FOR ADDITIONAL DEVELOPMENT. THE ONLY HINDRANCE IS THE UPPER-LEVEL WIND PATTERN. THE SYSTEM LIES TO THE SOUTHEAST OF A LARGE UPPER-LEVEL ANTICYCLONE WHICH IS GENERATING MODERATE TO STRONG NORTHEASTERLY FLOW OVER TOP OF THE SYSTEM, PUSHING THE CONVECTION OFF THE CENTER TO THE SOUTHWEST. THE WINDS REMAIN STRONGLY DIVERGENT HOWEVER, ALLOWING FOR PERSISTENT CONVECTIVE DEVELOPMENT. MODELS SUGGEST THAT WHILE THE UPPER-LEVEL PATTERN IS NOT EXPECTED TO CHANGE SIGNIFICANTLY, THE WINDS ARE EXPECTED TO WEAKEN, WHICH SHOULD ALLOW FOR THE SYSTEM TO QUICKLY CONSOLIDATE AND INTENSIFY. GLOBAL MODELS ARE IN GENERAL AGREEMENT ON A WESTWARD TRACK TOWARDS THE NORTHEAST TIP OF LUZON OR LUZON STRAIT, THEN A TURN TOWARDS THE NORTHWEST AFTER CROSSING OVER THE ISLAND OR PASSING THROUGH THE STRAIT. ENSEMBLE GUIDANCE SHOWS A LARGE DEGREE OF SPREAD AFTER PASSAGE THROUGH THE STRAIT, WITH MEMBERS SHOWING POTENTIAL TRACKS BETWEEN HONG KONG TO CENTRAL TAIWAN. THE MAJORITY OF THE INTENSITY GUIDANCE SUGGEST A QUICK INTENSIFICATION UP TO TROPICAL STORM STRENGTH PRIOR TO REACHING THE LUZON REGION FOLLOWED BY SOME ADDITIONAL INTENSIFICATION THEREAFTER. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 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 CANCELED BY 220800Z.//