WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUBTROPICAL STORM 02W (SURIGAE) 
WARNING NR 043//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUBTROPICAL STORM (SS) 02W (SURIGAE), LOCATED APPROXIMATELY 570
NM WEST OF IWO TO, HAS TRACKED EAST-SOUTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A BROAD, EXPOSED LOW-LEVEL CIRCULATION WITH ISOLATED, FLARING DEEP CONVECTION CONFINED TO THE EASTERN QUADRANT ASSOCIATED WITH A SHORTWAVE TROUGH PROPAGATING NORTHEASTWARD OVER THE NORTHERN QUADRANT OF THE SYSTEM. VISIBLE IMAGERY AND A 232228Z SSMIS 91GHZ COLOR COMPOSITE IMAGE REVEAL TIGHTLY-CURVED SHALLOW BANDING WRAPPING INTO A WELL-DEFINED CENTER SUPPORTING THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS HEDGED SLIGHTLY ABOVE THE PGTW SUBTROPICAL INTENSITY ESTIMATE (USING THE HEBERT-POTEAT SUBTROPICAL METHOD) OF ST3.0 (45-50 KNOTS) BASED ON RECENT ASCAT DATA AND THE WELL-ORGANIZED LOW-LEVEL STRUCTURE. SS 02W IS EMBEDDED WITHIN THE SUBTROPICAL WESTERLIES UNDER 40-50 KNOTS OF WESTERLY VERTICAL WIND SHEAR AND IS TRACKING OVER COOLER SST (24-25C) ALONG WITH SIGNIFICANT MID-LEVEL DRY AIR ENTRAINMENT.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. SS 02W (SURIGAE) WILL CONTINUE STEADILY WEAKENING OVER THE 
NEXT 24 HOURS AS IT LOSES BAROCLINIC SUPPORT FROM THE UPPER-LEVEL 
SHORTWAVE TO THE NORTH BUT IS EXPECTED TO RETAIN GALE-FORCE WINDS. AROUND TAU 36, A SECOND SHORTWAVE TROUGH CURRENTLY ENTERING THE YELLOW SEA WILL APPROACH SURIGAE, REINTRODUCING BAROCLINIC FORCING. THIS MAY STRENGTHEN AND INTENSIFY THE WIND FIELD SLIGHTLY BY 48 HOURS, AND WILL ALSO BRING ABOUT THE CONCLUSION OF EXTRATROPICAL TRANSITION. THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS ONE, PASSING NEAR IWO TO IN AROUND 36 HOURS. THE MODEL GUIDANCE ENVELOPE IS TIGHTLY CLUSTERED, WITH SOME SLIGHT VARIATION IN FORWARD SPEED. OVERALL, THIS FORECAST IS OF HIGH CONFIDENCE.//
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