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
H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. 5.5/10 BANDING AROUND THE LLCC YIELDS A DT OF 2.5. MET AND PT
ARE EQUAL TO 2.0 BASED ON A DEVELOPMENT TREND IN THE LAST 24 HOURS. FT
IS BASED ON MET AS BANDING FEATURES ARE NOT CLEAR CUT DUE TO PULSING
CONVECTION AROUND THE LLCC.
WTPN21 PGTW 130330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 94W) REISSUED//
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
120 NM EITHER SIDE OF A LINE FROM 7.1N 138.8E TO 9.1N 137.4E
WITHIN THE NEXT 06 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 130000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 7.3N 138.5E. THE SYSTEM IS MOVING WESTWARD AT 12 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 5.9N 141.5E IS NOW LOCATED NEAR 7.3N 138.5E, APPROXIMATELY 134
NM SOUTH OF YAP. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS PERSISTENT CONVECTION PARTIALLY OBSCURING A LOW LEVEL
CIRUCLATION CENTER (LLCC). A 122137 SSMIS 91GHZ SATELLITE IMAGE
DEPICTS MINOR LOWER LEVEL BANDING AND DEEP CONVECTION TO THE
NORTHERN PERIPHERY. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT FOR
DEVELOPMENT WITH WARM (29-30C) SEA SURFACE TEMPERATURES (SST), DUAL-
CHANNEL UPPER LEVEL OUTFLOW, AND LOW TO MODERATE (10-20 KTS)
VERTICAL WIND SHEAR (VWS). GLOBAL MODELS ARE IN AGREEMENT THAT
INVEST 94W WILL CONTINUE TO TRACK NORTHWESTWARD, CONSOLIDATE AND
STRENGTHEN FOR THE NEXT 48-96 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 REMAINS HIGH.
THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
140330Z.//
H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. IRREGULAR CDO WITH A DIAMETER GREATER THAN
1.5 DEG GIVES A DT OF 3.0. MET IS 2.0 AND PT IS
2.5. FT IS BASED ON PT DUE TO CDO VARYING IN SIZE
LAST FEW HR.
