WDPN31 PGTW 261200
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 04W WARNING NR 26//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. SUPER TYPHOON (STY) 04W (SONGDA), LOCATED APPROXIMATELY 250 NM 
EAST-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE 
IMAGERY AND RECENT MICROWAVE IMAGERY (260936Z CORIOLIS AND 261157Z 
SSMIS) DEPICT A 16 NM CONCENTRIC EYE-WALL WITH SPIRAL BANDING 
WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER FROM ALL QUADRANTS. 
THERE IS HIGH CONFIDENCE IN THE CURRENT POSITION AND MOTION BASED ON 
THE 26/1132Z PGTW EYE FIX AND THE SSMIS MICROWAVE IMAGE. THE CURRENT 
INTENSITY IS BASED ON DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD OF 
140 KNOTS. FUELED BY DUAL CHANNEL OUTFLOW, LOW VERTICAL WIND SHEAR 
(5-10 KNOTS), AND FAVORABLE SEA SURFACE TEMPERATURES, STY 04W HAS 
RAPIDLY INTENSIFIED OVER THE PAST 24 HOURS. THE SYSTEM IS CURRENTLY 
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED 
SUBTROPICAL STEERING RIDGE (STR) AND HAS SLOWED SLIGHTLY, INDICATING 
THE SYSTEM IS APPROACHING THE RIDGE AXIS AND SHOULD BEGIN TO TURN 
INCREASINGLY POLEWARD.
3. FORECAST REASONING.
   A. THERE ARE NO SIGNIFICANT CHANGES IN FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
   B. STY SONGDA IS FORECAST TO ROUND THE STR AND MAINTAIN SUPER 
TYPHOON INTENSITY THROUGH TAU 24, BUT WILL GRADUALLY WEAKEN AS IT 
TRACKS TOWARD OKINAWA, JAPAN AND ENCOUNTERS INCREASING VERTICAL WIND 
SHEAR AND LESS FAVORABLE SEA SURFACE TEMPERATURES NEAR 25 DEGREES 
NORTH LATITUDE. STY 04W WILL BEGIN TO INTERACT WITH THE MID-LATITUDE 
WESTERLIES BY TAU 48. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT 
ON BOTH TRACK AND INTENSITY THROUGH TAU 48, BUT DIFFERS SLIGHTLY IN 
TRACK SPEED. EGRR AND JGSM REMAIN THE SLOWER MODELS, WHILE NOGAPS 
AND GFDN ARE SLIGHTLY FASTER. THE JTWC FORECAST IN THE EARLY TAUS 
REMAINS SLIGHTLY INSIDE AND FASTER THAN CONSENSUS, AND IS CONSISTENT 
WITH THE PREVIOUS JTWC FORECAST TRACK.
   C. IN THE EXTENDED TAUS, STY 04W IS FORECAST TO ACCELERATE AND 
WEAKEN RAPIDLY IN RESPONSE TO A DEEP MID-LATITUDE SHORT-WAVE TROUGH. 
DYNAMIC AIDS ARE IN GOOD GENERAL AGREEMENT AS FAR AS THE DEVELOPMENT 
OF A HIGH-GALE TO STORM FORCE LOW AFTER TAU 72, BUT OVER THE PAST 12-
24 HOURS, THERE HAS BEEN A DISTINCT POLEWARD TREND IN MODEL 
TRACKERS, WITH NOGAPS, GFDN, AND GFS BRINGING THE SYSTEM INLAND JUST 
SOUTH OF KYOTO, JAPAN. BASED ON THIS TREND, THE CURRENT FORECAST HAS 
SHIFTED SLIGHTLY POLEWARD FROM THE PREVIOUS JTWC FORECAST, BUT 
REMAINS INSIDE AND FASTER THAN MODEL CONSENSUS. BASED ON THE 
FORECASTED MID-LATITUDE TROUGH-RIDGE PATTERN, AND KNOWN MODEL ERROR 
IN A RE-CURVE TYPE SCENARIO, A TRACK OVER SOUTHERN HONSHU DOES NOT 
SEEM LIKELY AT THIS TIME.//
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