Tropical Storm PRAPIROON Advisory mer, 10.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W (PRAPIROON) WARNING NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 22W (PRAPIROON), LOCATED APPROXIMATELY 505 NM SOUTH-
SOUTHEAST OF KADENA AIR BASE, OKINAWA, JAPAN, HAS TRACKED WEST-
NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS THE ORGANIZATION OF THE LOW
LEVEL CIRCULATION CENTER (LLCC) HAS UNDERGONE A PERIOD OF RAPID
INTENSIFICATION WITH RECENT INTENSITY ESTIMATES RANGING FROM 77 TO
90 KNOTS. THE CURRENT INTENSITY OF 85 KNOTS IS BASED PRIMARILY ON
THE 5.0/5.0 DVORAK ESTIMATES FROM PGTW AND RJTD, BUT REFLECTS THE
4.5/4.5 DVORAK FROM KNES AS WELL. STRONG BANDING FEATURES NOW WRAP
COMPLETELY AROUND THE LLCC, WITH A 092109Z SSMIS MICROWAVE IMAGE
SUPPORTING THE RECENT IMPROVEMENT IN THE LLCC STRUCTURE AND
POSITIONING. THE SYSTEM CONTINUES TO TRACK STEADILY ALONG THE
SOUTHWESTERN EDGE OF THE SUBTROPICAL RIDGE (STR). UPPER LEVEL
ANALYSIS INDICATES THE LLCC IS SLIGHTLY WEST OF A POINT SOURCE
ANTICYCLONE, WHICH IS PROVIDING GOOD RADIAL VENTILATION AND LOW
VERTICAL WIND SHEAR (VWS) OVER THE SYSTEM.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 22W IS EXPECTED TO TRACK SLOWLY WEST-NORTHWESTWARD OVER THE
NEXT 36 HOURS ALONG THE SOUTHWESTERN QUADRANT OF THE STR AS A MID-
LATITUDE TROUGH IS WEAKENING THE STR. BETWEEN TAU 36 AND 72 A NEAR
EQUATORIAL RIDGE (NER) IS EXPECTED TO BUILD TO THE SOUTHEAST OF THE
SYSTEM, BECOMING THE DOMINANT STEERING FLOW, SHIFTING THE TRACK TO
THE NORTHEAST. TRACK SPEEDS WILL REMAIN SLOW AS THE NER BUILDS
TOWARDS THE STR. FAVORABLE UPPER LEVEL OUTFLOW AND SURFACE
CONDITIONS WILL ALLOW THE SYSTEM TO INTENSIFY THROUGH TAU 48 TO 72.
   C. AFTER TAU 72, TY PRAPIROON WILL MOVE INTO A LESS FAVORABLE
UPPER LEVEL ENVIRONMENT (INCREASING VWS AND WEAKER POLEWARD OUTFLOW)
WITH DECREASING SEA SURFACE TEMPERATURES. THESE SLIGHT CHANGES WILL
START TO HINDER DEVELOPMENT BEYOND TAU 72, LEADING TO A WEAKENING
TREND THROUGH TAU 120. MODEL GUIDANCE REMAINS CONSISTENT WITH A
RECURVATURE SCENARIO IN THE NEXT 24 TO 36 HOURS, HOWEVER THE TIMING
REMAINS UNCERTAIN. ECMF AND GFS ARE THE WESTERN OUTLIERS, YET APPEAR
TO HAVE THE GREATEST HANDLE ON THE TRACK. THIS IS BASED ON THEIR
STEADY WEST-NORTHWESTWARD TRACK IN THE INITIAL TAUS, WHERE NGPS,
WBAR AND GFDN CONTINUE TO SHOW A SHARPER, EARLIER TURN. THIS
FORECAST FAVORS THE GFS AND ECMF SOLUTIONS BY KEEPING THE TRACK WEST
OF CONSENSUS AND SLOWER THROUGHOUT THE FORECAST. BASED ON THE
SHIFTING DYNAMIC MODEL GUIDANCE AND THE TIMING OF THE RECURVATURE,
CONFIDENCE IN THE FORECAST TRACK REMAINS LOW.//
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