Subject: Pacific-NW: 1. Formation Of A Significant Tropical Cyclone Is Possible Within

From: SIU Weather Processor <[email-masked]>
Date: Wed, 20 Oct 2010 04:29:06 -0500

WTPN21 PGTW 200930
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
200 NM EITHER SIDE OF A LINE FROM 16.0N 148.1E TO 16.7N 140.5E
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 200900Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 16.3N 146.7E.  THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 12
KNOTS.
2. REMARKS: ANIMATED MULTISPECTRAL IMAGERY SHOWS SUSTAINED
CONVECTION ASSOCIATED WITH A DEVELOPING LOW LEVEL CIRCULATION CENTER
(LLCC) APPROXIMATELY 80 NM NORTHEAST OF SAIPAN. OBSERVATIONS FROM
SAIPAN INDICATE A 4 MB DROP IN SEA LEVEL PRESSURE OVER THE LAST 24
HOURS. ALSO, A 200346Z AMSR-E MICROWAVE IMAGE SHOWS FORMATIVE CURVED
BANDING INTO THE LLCC. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS
TO THE WEST OF A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL THAT
IS PROVIDING EQUATORWARD OUTFLOW. HOWEVER, AN ANTICYCLONE TO THE
NORTH IS SUPPRESSING THE POLEWARD OUTFLOW CHANNEL. THE CYCLONE IS
CURRENTLY IN AN AREA OF LOW VERTICAL WIND SHEAR AND IS EXPECTED TO
CONTINUE MOVING WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF
THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE TO THE NORTH. NUMERIC MODELS
INDICATE A GRADUAL DEVELOPMENT AS POLEWARD OUTFLOW IMPROVES WITH THE
SYSTEM'S REORIENTATION TO THE TUTT CELLS IN THE AREA. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. IN VIEW OF THE
IMPROVING ENVIRONMENT, THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELED BY
210930Z.//

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