WDPN32 PGTW 210300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
      A. TYPHOON (TY) 11W (VAMCO) HAS MAINTAINED AN INTENSITY
OF 105 KNOTS OVER THE PAST 12 HOURS AS SUPPORTED BY DVORAK
SATELLITE INTENSITY ESTIMATES FROM PGTW AND RJTD THAT HAD 
BEEN RANGING FROM 90 TO 115 KNOTS. MORE RECENTLY AN IRREGULAR 
AND CLOUD-FILLED EYE HAS TAKEN SHAPE, AND TRACK SPEED HAS 
INCREASED TO 05 KNOTS.
3. FORECAST REASONING.
      A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE 
PREVIOUS PROGNOSTIC REASONING BULLETIN. HOWEVER, BEYOND TAU
48, THE TRACK SPEEDS HAVE INCREASED IN RESPONSE TO A FASTER 
MODEL CONSENSUS. 
      B. TY 11W IS FORECAST TO GRADUALLY BEGIN TO EXIT A 
NEAR-QUASISTATIONARY STEERING ENVIRONMENT IN RESPONSE TO THE 
SUBTROPICAL RIDGE BUILDING BACK IN TO THE EAST OF THE TYPHOON. 
THE UPPER LEVEL LOW TO THE NORTHEAST THAT HAD BEEN PARTIALLY 
RESPONSIBLE FOR ERODING THE WESTERN EDGE OF THIS SUBTROPICAL 
STEERING RIDGE APPEARS TO BE FILLING IN ANIMATED WATER VAPOR 
IMAGERY. THE OTHER CULPRIT FOR WEAK STEERING, AN UPPER LEVEL 
SHORTWAVE TROUGH LOCATED SEVERAL DEGREES TO THE NORTH OF THE 
TYPHOON, ALSO APPEARS TO BE WEAKENING AND PULLING FURTHER 
AWAY FROM THE TROPICS. RIDGING IS EXPECTED TO BECOME THE 
PRIMARY STEERING MECHANISM WITHIN THE NEXT DAY AS THESE TWO 
SYSTEMS DECAY. FAVORABLE SEA SURFACE TEMPERATURES, LOW 
VERTICAL WIND SHEAR, AND SMALL PROFILE WILL ALLOW THE SYSTEM 
TO MAINTAIN TYPHOON CLASSIFICATION. THE OBJECTIVE MODEL AIDS 
ARE IN MOSTLY GOOD AGREEMENT WITH THIS SCENARIO. 
     C. BETWEEN TAU 72 AND 96 THE SYSTEM WILL BEGIN TO 
INTERACT WITH THE BAROCLINIC BOUNDARY. INCREASED VERTICAL 
WIND SHEAR AND DECREASED SEA SURFACE TEMPERATURES WILL ALSO
INCITE INCREASED BAROCLINICITY. THE SYSTEM WILL RAPIDLY
TRANSIT ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL 
RIDGE AND WILL BE NEAR 50N BY TAU 120. MODEL GUIDANCE SUGGESTS 
THAT THE TYPHOON WILL TRANSITION INTO A STRONG EXTRATROPICAL
SYSTEM.
FORECAST TEAM: DELTA//
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