WTPN21 PGTW 121130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/121121Z APR 21//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 121130)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 5.6N 141.5E TO 8.6N 140.8E
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 120600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 5.9N 141.5E. THE SYSTEM IS MOVING NORTHWESTWARD AT 07 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 5.6N 143.1E IS NOW LOCATED NEAR 5.9N 146.5E, APPROXIMATELY 488
NM SOUTH-SOUTHWEST OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND A 120858Z SSMIS 91GHZ MICROWAVE IMAGE REVEAL FLARING,
DEEP CONVECTION IN THE NORTHEASTERN PERIPHERY OF THE ASSESSED LOW
LEVEL CIRCULATION CENTER (LLCC). A 121030Z ASCAT-A SCATTEROMETRY
PASS INDICATES A DISORGANIZED LLCC ON THE SOUTHWESTERN EDGE OF
FLARING DEEP CONVECTION, WITH WINDS OF 20-25 KTS IN THE NORTHEASTERN
QUADRANT OF THE CIRCULATION AND 15-20 KTS ELSEWHERE. INVEST 94W IS
IN A FAVORABLE ENVIRONMENT FOR TROPICAL DEVELOPMENT WITH ROBUST
WESTWARD AND EQUATORWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND
SHEAR, AND WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE
IN GOOD AGREEMENT THAT INVEST 94W WILL STEADILY INTENSIFY AS IT
TRACKS TO THE NORTHWEST OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH. THIS SUPERSEDES REF A.3. THIS ALERT WILL BE REISSUED,
UPGRADED TO WARNING OR CANCELLED BY 131130Z.
//
NNNN
(1) THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 4.4N 144.5E IS NOW LOCATED NEAR 4.8N 144.0E, APPROXIMATELY 516
NM SOUTH OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
REVEALS SYMMETRICAL FLARING CONVECTION NEAR THE ASSESSED LOW LEVEL
CIRCULATION (LLC). A PARTIAL 111048Z ASCAT-A PASS DEPICTS THE
EASTERN SIDE OF AN ELONGATED LLC WITH 15-20 KT WINDS PRESENT TO THE
NORTH AND SOUTH OF THE LLC. INVEST 94W IS IN A FAVORABLE ENVIRONMENT
FOR TROPICAL DEVELOPMENT WITH ROBUST WESTWARD AND EQUATORWARD
OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (29-30C)
SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT
THE CIRCULATION IN ASSOCIATION WITH INVEST 94W WILL CONTINUE TO
CONSOLIDATE AND INTENSIFY AS IT TRACKS TO THE NORTHWEST OVER THE
NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18
TO 23 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 IS UPGRADED TO MEDIUM.
