Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Storm 10w Warning Nr 20//

From: SIU Weather Processor <[email-masked]>
Date: Mon, 6 Sep 2010 08:51:04 -0500

WDPN33 PGTW 061500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W WARNING NR 20//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 10W (MALOU), LOCATED APPROXIMATELY 25 NM
SOUTH-SOUTHWEST OF CHEJU ISLAND, HAS TRACKED NORTHEASTWARD AT 08
KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
SHOWS INCREASED CENTRAL CONVECTION OVER A BROAD LOW LEVEL
CIRCULATION CENTER (LLCC). A 061025Z 91H SSMIS MICROWAVE IMAGE
DEPICTS THE DEEPER CONVECTION IS LOCATED TO THE NORTHEAST OF THE
LLCC. THE INITIAL POSITION IS BASED ON THE SSMIS IMAGE AND A RJTD
RADAR FIX. THE INITIAL INTENSITY IS BASED ON DVORAK ESTIMATES
RANGING FROM 45 TO 55 KNOTS FROM PGTW, KNES, AND RJTD, AS WELL AS 35
KNOT WIND SURFACE OBSERVATIONS TO THE SOUTHEAST. SURFACE
OBSERVATIONS ON CHEJU ISLAND (40 NM TO THE NORTHEAST) HAVE BEEN
INDICATING 15 TO 25 KNOT WINDS. UPPER LEVEL ANALYSIS SHOWS THE
POLEWARD OUTFLOW HAS INCREASED INTO THE WESTERLIES AND EQUATORWARD
OUTFLOW HAS DECREASED.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE FROM THE PREVIOUS FORECAST
PHILOSOPHY. HOWEVER, THIS FORECAST TRACK HAS SHIFTER TO THE RIGHT
WITH A FASTER RECURVATURE INTO THE MID-LATITUDE WESTERLIES.
   B. TS 10W IS CURRENTLY ROUNDING THE SUBTROPICAL RIDGE AXIS SOUTH
OF CHEJU ISLAND AND IS NOW TRACKING ALONG THE NORTHWESTERN PERIPHERY
OF THE STEERING RIDGE. TS MALOU IS FORECAST TO GRADUALLY WEAKEN AS
IT BEGINS TO INTERACT WITH THE BAROCLINIC ZONE TO THE NORTH WITHIN
12 HOURS. BY TAU 24, TS 10W IS EXPECTED TO BECOME FULLY ABSORBED
INTO THE MID-LATITUDE WESTERLY FLOW OVER THE SEA OF JAPAN. NUMERICAL
MODEL GUIDANCE IS IN FAIR AGREEMENT EXCEPT FOR GFDN AND NOGAPS WHICH
TRACK THE SYSTEM NORTHWARD. THIS FORECAST IS IN GOOD AGREEMENT WITH
THE MODEL CONSENSUS AND IS WITHIN THE TIGHT PACKING OF GFS, JGSM,
ECMWF, EGRR, AND WBAR, WHICH RECURVE TS 10W INTO THE MID-LATITUDE
WESTERLY FLOW. //

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