WDPN31 PGTW 140300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W WARNING NR 23//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TYPHOON (TY) 15W HAS WEAKENED DUE TO INTERACTION WITH TAIWAN
OVER THE PAST 12 HOURS. THE SYSTEM MADE LANDFALL AROUND 13/17Z,
WHILE TRACKING WESTWARD, AND IMMEDIATELY STARTED A CYCLONIC LOOP
ALONG THE NORTHEAST COAST. THE SYSTEM TRACKED BACK OVER WATER NEAR
13/22Z AND RADAR DATA NOW INDICATES THAT TY 15W HAS BEGUN TO TRACK
NORTHWARD. ANIMATED SATELLITE IMAGERY AND A RECENT SSMIS IMAGE
INDICATE THAT THE SYSTEM HAS WEAKENED SIGNIFICANTLY BUT HAS RETAIN-
ED TIGHTLY-CURVED BANDING OVER THE EASTERN SEMI-CIRCLE. THE MODEL
GUIDANCE IS IN GOOD AGREEMENT WITH THE RE-CURVE SCENARIO WITH THE
EXCEPTION OF NOGAPS, WHICH IS WEAKENING THE SYSTEM TOO RAPIDLY. 
   B. THE LATEST 500 MB ANALYSIS INDICATES THAT THE SYSTEM IS
POSITIONED WITHIN A WEAK STEERING ENVIRONMENT IN THE BREAK BETWEEN
THE WESTERN AND EASTERN SUBTROPICAL RIDGE (STR). THERE ARE CLEAR
INDICATIONS THAT THE EASTERN STR HAS STRENGTHENED OVER THE PAST
24 HOURS WITH ASSOCIATED HEIGHT RISES AND STRONGER SOUTHERLY
FLOW OVER THE WESTERN PERIPHERY OF THE STR. THE VAD WIND PROFILE
OUT OF OKINAWA SHOWS SOUTHERLY WINDS AT 25-35 KNOTS FROM 15,000
TO 20,000 FEET. 
   A. OTHER THAN SLIGHT INTENSITY ADJUSTMENTS, THE FORECAST PHILOS-
OPHY HAS REMAINED UNCHANGED.
   B. BASED ON THE 500 MB ANALYSIS PREVIOUSLY DISCUSSED IN DETAIL
AS WELL AS THE RECENT NORTHWARD MOTION, THERE IS RENEWED CONFIDENCE
IN THE FORECAST TRACK AND RE-CURVATURE SCENARIO. THE EASTERN STR
IS NOW THE DOMINANT STEERING RIDGE AND IS FORECAST TO PRODUCE A
POLEWARD TRACK THAT WILL EVENTUALLY MOVE THE SYSTEM INTO THE MID-
LATITUDE WESTERLIES AND ALLOW THE SYSTEM TO RE-CURVE. THE AVAILABLE
MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE FORECAST TRACK AND THE
CURRENT FORECAST IS CLOSE TO THE CONSENSUS. TY 15W IS EXPECTED TO
MAINTAIN TYPHOON STRENGTH THROUGH TAU 48 UNDER GENERALLY FAVORABLE
CONDITIONS WITH ENHANCED POLEWARD OUTFLOW THE IMPETUS FOR SOME
IMPROVED CONSOLIDATION ONCE THE SYSTEM MOVES AWAY FROM TAIWAN.
THE SYSTEM REMAINS A LARGE TYPHOON WITH A RADIUS OF 240 NM, SO
COULD PRODUCE STRONG WINDS OVER OKINAWA NEAR CPA WITH A CLOSER
TRACK POSSIBLE DEPENDING ON HOW QUICKLY THE SYSTEM RE-CURVES.
   C. IN THE EXTENDED TAUS, TY 15W WILL TRACK EAST-NORTHEASTWARD
WITHIN THE MIDLATITUDE WESTERLIES AND ENCOUNTER STRONGER VERTICAL
WIND SHEAR, WHICH WILL SERVE TO WEAKEN THE SYSTEM. TY 15W SHOULD
BEGIN TO INTERACT WITH THE BAROCLINIC ZONE NEAR TAU 72 AND BEGIN
EXTRA-TROPICAL TRANSITION (ETT), COMPLETING ETT BY TAU 120. 
FORECAST TEAM: CHARLIE//
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