WDPN31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W (PRAPIROON) WARNING NR 09//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) TYPHOON 22W (PRAPIROON), LOCATED APPROXIMATELY 555 NM
SOUTH-SOUTHEAST OF KADENA AIR BASE, OKINAWA, JAPAN, HAS TRACKED WEST-
NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED (EIR) SATELLITE IMAGERY (MSI) SHOWS SLIGHTLY DEEPENED
CENTRAL CONVECTION AS THE SYSTEM SLOWED DOWN AND GAINED LATITUDE. THE
INITIAL POSITION IS BASED ON THE EIR ANIMATION AND EXTRAPOLATED FROM
A MICROWAVE EYE FEATURE ON A 090849Z TRMM IMAGE. THE INITIAL INTENSITY
IS SLIGHTLY HIGHER THAN THE CONGRUENT DVORAK ESTIMATES OF 65 KNOTS
FROM PGTW, KNES, AND RJTD TO REFLECT THE DEEPENED CENTRAL CONVECTION.
UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS APPROACHING THE WESTERN
EDGE OF A RIDGE AXIS IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL WIND
SHEAR (VWS). THE CYCLONE IS TRACKING ALONG THE SOUTHERN EXTENSION OF
A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST-NORTHEAST. 
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 22W IS EXPECTED TO ROUND THE WESTERN EDGE OF THE STR AND
RECURVE NORTHEASTWARD OVER THE NEXT 72 HOURS AS A MID-LATITUDE TROUGH
DIGGING IN FROM THE NORTHWEST WEAKENS THE STR. CONTINUED FAVORABLE
UPPER AND LOW LEVEL ENVIRONMENT WILL ALLOW TY 22W TO INTENSIFY
THROUGH TAU 48 BEFORE INCREASING VWS AND COOLING SEA SURFACE
TEMPERATURES BEGIN TO ERODE THE SYSTEM. 
   C. AFTER TAU 72, TY PRAPIROON WILL BEGIN TO ACCELERATE NORTHEAST-
WARD AND CONTINUE TO ERODE AS IT GETS EMBEDDED DEEPER INTO THE STRONG
WESTERLIES. MODEL GUIDANCE UNANIMOUS WITH A RECURVATURE SCENARIO BUT
HAS SIGNIFICANT TIMING/SPEED DIFFERENCES. THIS FORECAST FAVORS ECMWF
AND GFS WITH A LATER/SLOWER TIMING ON THE RECURVATURE. THE CONFIDENCE
IN THE FORECAST REMAINS LOW DUE TO THE WIDE VARIATION IN THE MODEL
GUIDANCE.   //
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