WDPN31 PGTW 131500
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W WARNING NR 21//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TYPHOON (TY) 15W HAS REINTENSIFIED SLIGHTLY AFTER UNDERGOING
REPLACEMENT OF THE EYEWALL WHILE TRACKING NORTHWESTWARD AT 03 KNOTS
OVER THE PAST 06 HOURS. THIS REINTENSIFICATION IS EVIDENT IN ANIMATED
METSAT IMAGERY WHICH DEPICTS IMPROVED OUTFLOW COUPLING IN THE UPPER
LEVELS, AND WELL DEFINED INFLOW ON THE EQUATORWARD SIDE OF THE STORM
DESPITE INCREASED INTERACTION WITH LAND. ANIMATED INFRARED SATELLITE
IMAGERY DEPICTS TIGHTLY-CURVED BANDING WITH A RAGGED EYE FEATURE, AND
A 131110Z SSMIS IMAGE SHOWS WELL-DEFINED, INTENSE BANDING WITH DEEP
CONVECTION WRAPPING INTO THE CENTER. THERE IS HIGH CONFIDENCE IN
BOTH THE CURRENT POSITION AND THE 12-HOUR STORM MOTION DUE TO THE 
AVAILABILITY OF RADAR FIXES AND WELL-DEFINED LOW-LEVEL CIRCULATION
CENTER (LLCC). THE AVAILABLE MODEL GUIDANCE HAS BECOME MORE ALIGNED
WITH MOST AIDS DEPICTING A RECURVATURE NORTH OF TAIWAN NEAR TAU 24.
   B. THE SYSTEM CONTINUES TO TRACK PRIMARILY UNDER THE STEERING
INFLUENCE OF THE MID-LEVEL SUBTROPICAL RIDGE (STR) LOCATED NORTH
OF THE SYSTEM. THE MOST RECENT 500MB ANALYSIS INDICATES A SMALL BREAK
BETWEEN A WESTERN STR AND AN EASTERN STR, HOWEVER ZONAL FLOW DOMINATES
THE REGION NORTH OF THE STR WITH NO SIGNIFICANT MIDLATITUDE SHORTWAVE
TROUGHS MOVING INTO THE REGION. THE SYSTEM DISPLAYS GOOD RADIAL OUT-
FLOW WHICH HAS HELPED SUPPORT THE RECENT SURGE IN INTENSITY. THE
CURRENT POSITION IS BASED ON RADAR FIXES AND IS SUPPORTED BY THE 
131110Z SSMIS IMAGE. THE CURRENT INTENSITY IS BASED ON DVORAK ESTI-
MATES RANGING FROM 77 TO 102 KNOTS.
   A. TRACK PHILOSOPHY HAS NOT CHANGED SINCE THE PREVIOUS PROG REAS-
ONING; HOWEVER, THE INITIAL INTENSITIES WERE ADJUSTED SLIGHTLY TO
REFLECT THE RECONSOLIDATION OF THE EYEWALL AND IMPROVED CONVECTIVE
BANDING WRAPPING INTO THE LLCC.  
   B. THE FORECAST TRACK PHILOSOPHY IS BASED ON THE EXPECTED
STRENGTHENING OF THE EASTERN STR, WHICH IS EXPECTED TO ALLOW THE
SYSTEM TO TRACK NORTHWARD INTO THE MIDLATITUDE WESTERLY FLOW. THE
DYNAMIC MODELS INDICATE A DOMINANT STEERING RIDGE EAST OF THE
SYSTEM AFTER TAU 12. MOST MODEL AIDS ARE IN AGREEMENT WITH THE 
RECURVATURE SCENARIO, HOWEVER NOGAPS AND GFDN CONTINUE TO STRUGGLE
WITH THE TRACK FORECAST AND SHOW CLEAR INDICATIONS OF UNDERFORECAST-
ING THE SYSTEM STRENGTH NEAR TAIWAN. TY 15W IS FORECAST TO WEAKEN 
AS IT TRACKS NEAR TAIWAN AND MAY RE-INTENSIFY SLIGHTLY ONCE IT
CLEARS LAND AND POLEWARD OUTFLOW IMPROVES, BUT THIS WILL BE SHORT-
LIVED AS THE SYSTEM ACCELERATES TOWARDS THE MIDLATITUDE FLOW.
   C. IN THE EXTENDED RANGES, THE SYSTEM WILL TRACK INCREASINGLY
NORTHEASTWARD WITHIN THE STRONG WESTERLY FLOW AND WILL ACCELERATE,
WEAKEN FURTHER, AND UNDERGO EXTRA-TROPICAL TRANSITION BY TAU 120. 
FORECAST TEAM: DELTA//
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