WTPN21 PGTW 280600
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
160 NM EITHER SIDE OF A LINE FROM 10.3N 146.0E TO 12.7N 139.6E 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 280530Z INDICATES
THAT A CIRCULATION CENTER IS LOCATED NEAR 10.6N 145.5E. THE SYSTEM IS
MOVING WEST-NORTHWESTWARD AT 14 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED
NEAR 9.9N 146.7E IS NOW LOCATED NEAR 10.6N 145.5E, APPROXIMATELY 173
NM SOUTH-SOUTHEAST OF GUAM. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A SLOWLY-DEVELOPING LOW-LEVEL CIRCULATION (LLC) WITH LOW-LEVEL
CLOUD LINES WRAPPING INTO A WEAKLY-DEFINED CENTER, AND DEEP CONVECTION
FLARING OVER THE LLC. A 280336Z AMSR2 89GHZ COLOR COMPOSITE MICROWAVE
IMAGE SHOWS INCIPIENT LOW-LEVEL BANDING OVER THE SOUTHERN SEMICIRCLE
WITH EXTENSIVE FRAGMENTED BANDING OVER THE NORTHERN SEMICIRCLE
ASSOCIATED WITH CONVERGENT LOW-LEVEL EASTERLIES. SURFACE OBSERVATIONS
FROM GUAM INDICATE VIGOROUS NORTHEASTERLY WINDS AT 15-20 KNOTS GUSTING
TO 25-30 KNOTS. ENVIRONMENTAL ANALYSIS INDICATES GENERALLY FAVORABLE
CONDITIONS WITH LOW TO MODERATE (10-15KTS) VWS, WARM (29-30C) SEA
SURFACE TEMPERATURES AND GOOD POLEWARD OUTFLOW. OVER THE NEXT ONE TO
TWO DAYS, GLOBAL MODELS INDICATE GRADUAL DEVELOPMENT AND CONSOLIDATION
INTO A DISCRETE LLC WITH A GENERALLY WEST-NORTHWESTWARD TO
NORTHWESTWARD TRACK SOUTH AND SOUTHWEST OF GUAM. HOWEVER, VIGOROUS
NORTHEASTERLY WINDS WILL MAINTAIN OVER GUAM DURING THIS PERIOD.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 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
290600Z.//
NNNN
ABPW10 PGTW 280130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS/REISSUED/280130Z-280600ZNOV2021//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED
NEAR 7.3N 152.1E IS NOW LOCATED NEAR 9.9N 146.7E, APPROXIMATELY 232
NM SOUTH-SOUTHEAST OF GUAM. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND A 272101Z SSMIS 91GHZ MICROWAVE IMAGE SHOW A DISJOINTED PATCH OF
CONVECTION ON THE NORTHERN PERIPHERY OF A TROPICAL WAVE. A PARTIAL
2341Z ACSAT-B IMAGE REVEALS 15-20KT WINDS NORTH OF THE WAVE CUSP
WHILE ASLO REVEALING SHARP CYCLONIC TURNING TO THE WEST OF THE WAVE
AXIS. THERE IS ALSO SOME WEAK RETURN FLOW EVIDENT IN ANIMATED
VISIBLE IMAGERY AND AS OF YET THERE IS NO CLEAR LOW LEVEL
CIRCULATION (LLC). ENVIRONMENTAL ANALYSIS INDICATES AN OVERALL
FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW TO MODERATE (05-
15KTS) VWS, WARM (29-30C) SEA SURFACE TEMPERATURES AND GOOD POLEWARD
OUTFLOW. WHILE THERE IS NO CLOSED ISOBAR OR CLOSED LLC AT THIS TIME,
GLOBAL MODELS ARE IN AGREEMENT THAT A CLOSED CIRCULATION CENTER WILL
DEVELOP IN THE NORTHERN CUSP OF THE TROPICAL WAVE WITHIN THE NEXT 12
TO 24 HOURS, FOLLOWED BY RAPID CONSOLIDATION AND INTENSIFICATION IN
THE 24 HOURS FOLLOWING. 93W WILL GENERALLY TRACK TO THE NORTHWEST
OVER THE NEXT 48 HOURS AND DEVELOP LIKE A HOUSE ON FIRE. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM.
(2) NO OTHER SUSPECT AREAS.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
3. JUSTIFICATION FOR REISSUE: UPGRADED AREA IN 1.B.(1) TO MEDIUM.//
NNNN
(1) AN AREA OF CONVECTION (INVEST 93W) HAS PERSISTED NEAR 8.3N
156.4E, APPROXIMATELY 752 NM EAST-SOUTHEAST OF GUAM. ANIMATED
ENHANCED INFRARED SATELLITE IMAGERY (EIR) AND A RECENT SCATTEROMETRY
PASS DEPICT A TROPICAL WAVE WITH WINDS 15-20 KT. ENVIRONMENTAL
ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT FOR
DEVELOPMENT WITH ROBUST POLEWARD OUTFLOW ALOFT AND WARM (29-30C) SEA
SURFACE TEMPERATURES, OFFSET BY HIGH (30-35KT) VERTICAL WIND SHEAR.
NVGM, CMC, GFS AND ITS ENSEMBLES ARE IN GOOD AGREEMENT THAT 93W WILL
WILL TRACK WEST-NORTHWESTWARD AND CONSOLIDATE IN THE VICINITY OF
GUAM OVER THE NEXT 48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.
