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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