Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Storm 13w Warning Nr 16//

From: SIU Weather Processor <[email-masked]>
Date: Thu, 23 Sep 2010 21:18:04 -0500

WDPN32 PGTW 240300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W WARNING NR 16//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TYPHOON (TY) 13W (MALAKAS), LOCATED APPROXIMATELY 40 NM
WEST-SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTHWARD AT 16 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND A 232253Z SSMIS MICROWAVE IMAGE SHOW A LARGE RAGGED EYE WITH
MULTIPLE CONVECTIVE BANDS WRAPPING AROUND THE SOUTHEASTERN TO
NORTHERN PERIPHERY. THE INITIAL POSITION IS BASED ON A 232216Z ITOP
VORTEX MESSAGE AS WELL AS A PGTW FIX. THE INITIAL INTENSITY IS BASED
ON DVORAK ESTIMATES FROM PGTW AND RJTD RANGING FROM 77 TO 90 KNOTS.
SURFACE LEVEL WIND OBSERVATIONS AT 240048Z FROM IWO JO ARE REPORTING
49 KNOT WINDS WITH 98 KNOT GUSTS. INCREASED POLEWARD OUTFLOW INTO A
MID-LATITUDE UPPER LEVEL TROUGH TO THE NORTHWEST AND GOOD
EQUATORWARD OUTFLOW HAS ALLOWED TY 13W TO INTENSIFY BY 10 KNOTS OVER
THE PAST SIX HOURS.
3. FORECAST REASONING.
   A. THIS FORECAST PREDICTS A HIGHER MAXIMUM INTENSITY THAN THE
PREVIOUS FORECAST BASED ON THE INTENSIFICATION TREND.
   B. TY 13W IS EXPECTED TO CONTINUE TRACKING ALONG THE WESTERN
PERIPHERY OF
A SUBTROPICAL STEERING RIDGE AND INTENSIFY OVER THE NEXT 12 HOURS AS
POLEWARD OUTFLOW INCREASES INTO THE APPROACHING UPPER LEVEL TROUGH.
BY TAU 24, TY 13W SHOULD BEGIN TO ROUND THE RIDGE AXIS AND BEGIN TO
INTERACT WITH THE MID-LATITUDE WESTERLIES. BY TAU 48, TY MALAKAS
IS FORECAST TO BECOME ABSORBED BY THE STRONG BAROCLINIC ZONE TO THE
NORTH. WITH THE UPPER LEVEL SUPPORT OF THE MID-LATITUDE TROUGH, TY
13W IS EXPECTED TO TRANSITION INTO AN INTENSE EXTRATROPICAL LOW.
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT. THEREFORE, THIS
FORECAST IS IN AGREEMENT WITH MODEL CONSENSUS.//

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