WTPN21 PGTW 300730
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 94W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 20.3N 133.8E TO 21.5N 130.8E
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 20 TO 25 KNOTS. METSAT
IMAGERY AT 300600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 20.6N 133.3E. THE SYSTEM IS MOVING NORTHWESTWARD AT 05
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED 
NEAR 20.3N 133.7E IS NOW LOCATED NEAR 20.6N 133.3E, APPROXIMATELY 785 
NM NORTHWEST OF GUAM. THE SYSTEM IS CURRENTLY CLASSIFIED AS A MONSOON 
DEPRESSION, GENERALLY CHARACTERIZED AS A LARGE CYCLONIC CIRCULATION, 
GREATER THAN 600NM DIAMETER, WITH ELEVATED WINDS OVER THE SOUTHEASTERN 
PERIPHERY AND A WEAK CORE OF LIGHT WINDS. ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY DEPICTS A BROAD LOW-LEVEL CIRCULATION CENTER 
OBSCURED BY PERSISTENT CONVECTION ALONG THE WESTERN AND SOUTHERN 
EXTENT OF THE SYSTEM. A 292347Z METOP-B BULLSEYE ASCAT REVEALED WEAK 
WINDS NEAR THE CENTER OF 94W, SURROUNDED BY ELEVATED WINDS UP TO 25 
KTS. THE ENVIRONMENTAL ANALYSIS OF THE AREA INDICATES CONDUCIVE 
CONDITIONS FOR DEVELOPMENT WITH LOW (10-15 KTS) VERTICAL WIND SHEAR 
(VWS), WARM (29-30 C) SEA SURFACE TEMPERATURES, PLENTIFUL MOISTURE, 
AND A STRONG EQUATORWARD OUTFLOW IN THE UPPER LEVELS. ONLY A SLIGHT 
TIGHTENING OF THE WIND FIELD IS NEEDED TO DESIGNATE THE SYSTEM AS A 
TROPICAL DEPRESSION. THE MAJORITY OF GLOBAL AND ENSEMBLE MEMBERS 
INDICATE THAT 94W WILL HAVE A SHORT WINDOW TO CONSOLIDATE, AFTER WHICH 
TIME, THE CLOSED CIRCULATION WILL OPEN UP. 94W CURRENTLY LIES ALONG A 
TROUGH THAT EXTENDS FROM TAIWAN TO THE MARIANA ISLANDS. OVER THE NEXT 
FEW DAYS, DEVELOPMENT OF ADDITIONAL, NORTHWEST-TRACKING CIRCULATIONS 
ALONG THIS TROUGH WILL BE POSSIBLE. THAT MAY LEAD TO MORE DIRECT 
IMPACTS TO THE RYUKYU ISLANDS. WHILE THIS SCENARIO IS SUPPORTED BY 
ENSEMBLE SYSTEMS, THE SPECIFIC IMPACTS WILL BE PREDICATED ON THE 
EVOLUTION OF THESE SUBSEQUENT CIRCULATIONS, WHICH HAVE NOT YET FORMED. 
THEREFORE, SIGNIFICANT UNCERTAINTY EXISTS FOR TROPICAL CYCLONE 
POTENTIAL OVER THE NEXT FEW DAYS AS IT RELATES TO THE REGION OF THE 
EAST CHINA SEA. FOR HAZARDS AND WARNINGS, REFERENCE THE FLEET WEATHER 
CENTER SAN DIEGO HIGH WINDS AND SEAS PRODUCT OR REFER TO LOCAL WMO 
DESIGNATED FORECAST AUTHORITY. MAXIMUM SUSTAINED SURFACE WINDS ARE 
ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED 
TO BE NEAR 1002 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT 
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.
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 
310730Z.//
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