Subject: Pacific-NW: Ref/b/msg/navmarfcstcen Pearl Harbor Hi/210252zoct2010//

From: SIU Weather Processor <[email-masked]>
Date: Thu, 21 Oct 2010 04:52:13 -0500

WTPN21 PGTW 210930
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED//
REF/A/MSG/NAVMARFCSTCEN PEARL HARBOR HI/200921ZOCT2010//
REF/B/MSG/NAVMARFCSTCEN PEARL HARBOR HI/210252ZOCT2010//
NARR/REFS A AND B ARE TROPICAL CYCLONE FORMATION ALERTS.//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
145 NM EITHER SIDE OF A LINE FROM 16.9N 142.1E TO 17.0N 137.4E
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 15 TO 20 KNOTS. METSAT IM-
AGERY AT 210600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.0N 141.7E. THE SYSTEM IS MOVING WESTWARD AT 11 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED 16.3N 146.7E,
IS NOW LOCATED NEAR 17.0N 141.7E, APPROXIMATELY 280 NM NORTHWEST OF
ANDERSEN AFB, GUAM. A 210042Z ASCAT PASS SHOWS A WELL-DEFINED LOW
LEVEL CIRCULATION CENTER (LLCC) WITH WINDS APPROACHING WARNING
CRITERIA IN THE NORTHEASTERN, GRADIENT SIDE OF THE LLCC. HOWEVER,
RETURN FLOW ALONG THE WESTERN PERIPHERY OF THE CIRCULATION IS MUCH
WEAKER. A 210733Z SSMI MICROWAVE IMAGE HIGHLIGHTS THE LOCATION OF
THE LLCC TO A FAIR DEGREE OF CERTAINTY WITH A WEAK CONVECTIVE BAND
FLANKING THE EASTERN SIDE. MORE RECENTLY CONVECTION HAS BEGUN TO
SHALLOW AND FRAGMENT AS A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT)
CELL ENCROACHES FROM THE NORTHEAST AND SUPPRESSES UPWARD VERTICAL
MOTION. VERTICAL WIND SHEAR HAS ALSO ELEVATED DUE TO AN ENHANCED
GRADIENT BETWEEN THE TUTT CELL AND AN EXTENSION OF THE UPPER LEVEL
SUBTROPICAL RIDGE RUNNING ALONG 140E TO THE WEST OF THE DISTURBANCE.
THIS SHEAR HAS PERIODICALLY LEFT THE LLCC PARTIALLY EXPOSED ON THE
NORTH SIDE OF THE DEEPEST CONVECTION OVER THE PAST 24 HOURS. 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 REMAINS GOOD DUE TO AN APPRECIABLE LOW LEVEL CYCLONIC WIND
FIELD. THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
220930Z.
4. SEE REF B FOR DETAILS ON A TROPICAL CYCLONE FORMATION ALERT
LOCATED NEAR 19.2N 159.9E//

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