Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Storm 10w Warning Nr 16//

From: SIU Weather Processor <[email-masked]>
Date: Sun, 5 Sep 2010 09:24:07 -0500

WDPN33 PGTW 051500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W WARNING NR 16//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 10W (MALOU), LOCATED APPROXIMATELY 180 NM
SOUTH OF CHEJU ISLAND, HAS TRACKED NORTHWARD AT 10 KNOTS OVER THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS A BROAD
AREA OF CIRCULATION, RESEMBLING A MONSOON GYRE PATTERN, WITH
MULTIPLE SMALLER VORTICES EMERGING FROM THE CENTER AND ROTATING
CYCLONICALLY AROUND THE GYRE. A 051037Z 37GHZ SSMIS MICROWAVE IMAGE
ALSO DEPICTS
A BROAD CIRCULATION WITH THE MAJORITY OF THE CONVECTION WRAPPING
AROUND FROM THE SOUTHEASTERN TO NORTHERN PERIPHERY. TS 10W HAS
MAINTAINED AN INTENSITY OF 35 KNOTS BASED ON DVORAK ESTIMATES FROM
PGTW, KNES, AND RJTD. TS MALOU IS CURRENTLY LOCATED IN AN AREA OF
HIGH SEA SURFACE TEMPERATURES AND UPPER LEVEL DIVERGENCE.
ADDITIONALLY, AN UPPER LEVEL, MID-LATITUDE TROUGH TO THE NORTH HAS
ENHANCED POLEWARD OUTFLOW.
3. FORECAST REASONING.
   A. THIS FORECAST HAS BEEN RELOCATED FROM A SMALLER LOW LEVEL
CIRCULATION CENTER TO THE BROAD CIRCULATION CENTER SINCE THE
PREVIOUS PROGNOSTIC REASONING. BASED ON THE NEW POSITIONING, THE
FORECAST TRACK HAS SHIFTED EAST.
   B. TS 10W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A
SUBTROPICAL STEERING RIDGE. IT IS EXPECTED TO CONTINUE TRACKING
NORTHWARD, BEGIN TO ROUND THE STEERING RIDGE AFTER TAU 24, AND
BEGIN TO INTERACT WITH THE MID-LATITUDE WESTERLIES AFTER MAKING
LANDFALL OVER SOUTH KOREA. DUE TO FAVORABLE UPPER LEVEL CONDITIONS,
TS 10W IS FORECAST TO INTENSIFY OVER THE NEXT 12 HOURS. BY TAU 24,
TS MALOU SHOULD WEAKEN DUE TO THE INTERACTION WITH LAND AND
INCREASED VERTICAL WIND SHEAR ASSOCIATED WITH THE MID-LATITUDE
WESTERLIES. AVAILABLE NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH
THE NORTHWARD TRACK, HOWEVER THE MODELS RECURVE THE SYSTEM EASTWARD
AT DIFFERENT TIMES. THE ECMWF, WBAR, AND GFS MODELS RECURVE THE
SYSTEM SOON. THE GFDN MODEL IS AN OUTLIER THAT TRACKS THE SYSTEM
WESTWARD. THIS FORECAST IS IN AGREEMENT WITH THE JGSM AND UKMO
MODELS, WHICH RECURVE TS 10W AFTER REACHING SOUTH KOREA.
   C. BY TAU 72, TS 10W IS EXPECTED TO BECOME ABSORBED BY THE
BAROCLINC ZONE OVER THE SEA OF JAPAN AND BECOME A FULLY
EXTRATROPICAL SYSTEM.//

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