WDPN33 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W (FITOW) WARNING NR 18//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 22W (FITOW), LOCATED APPROXIMATELY 212 NM SOUTH-SOUTHEAST 
OF KADENA AB, OKINAWA, HAS TRACKED NORTHWESTWARD AT 05 KNOTS OVER 
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY 
SHOWS THE SYSTEM REMAINS WELL ORGANIZED WITH AN EYEWALL OF DEEP 
BROAD CONVECTION ENVELOPING THE LOW LEVEL CIRCULATION CENTER (LLCC). 
THE EYE HAS BECOME MORE SYMMETRIC OVER THE PAST SIX HOURS AS THE 
CONVECTION IMPROVES. THE CURRENT INTENSITY OF 85 IS BASED ON A RE-
ASSESSMENT OF THE DVORAK ESTIMATES FROM PGTW, KNES AND RJTD, ALL 
INDICATING A 77 KNOT SYSTEM AND DO NOT APPEAR TO REPRESENT THE 
IMPROVEMENT IN THE OVERALL STRUCTURE OF THE SYSTEM. UPPER LEVEL 
ANALYSIS INDICATES THE RADIAL OUTFLOW HAS MAINTAINED THE SYSTEM OVER 
THE PAST FEW HOURS, WITH A FAVORABLE TAP INTO THE MID-LATITUDE 
WESTERLIES SUPPORTING ADDITIONAL POLEWARD OUTFLOW. CURRENTLY THE 
VERTICAL WIND SHEAR (VWS) OVER THE LLCC HAS BEEN SLOWLY INCREASING 
TO MODERATE LEVELS (10 TO 15 KNOTS) AS THE SYSTEM CONTINUES TO 
INTERACT WITH THE MID-LATITUDE TROUGH. TY 22W HAS MAINTAINED A 
NORTHWESTWARD TRACK FOR THE PAST 12 HOURS AS THE SUBTROPICAL RIDGE 
(STR) CONTINUES TO BUILD WESTWARD. 
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TY 22W IS FORECAST TO REMAIN ON A NORTHWESTWARD TRACK OVER THE 
NEXT 24 HOURS, TURNING TO THE WEST-NORTHWEST AS THE STR BUILDS TO 
THE NORTH OF THE CIRCULATION. THE OVERALL ENVIRONMENT WILL REMAIN 
FAVORABLE FOR FURTHER DEVELOPMENT OF THE SYSTEM THROUGH TAU 36. FROM 
TAU 36 THROUGH 72, INCREASING DRY AIR ENTRAINMENT ALONG THE 
NORTHWESTERN QUADRANT, DECREASING SEA SURFACE TEMPERATURES (SST), 
AND THE EVENTUAL TRACK TOWARDS COASTAL CHINA WILL LEAD TO A STEADY 
WEAKENING OF TY 22W.
   C. AFTER TAU 72, TY 22W IS EXPECTED TO MAKE LANDFALL INTO 
MAINLAND CHINA. THE FRICTIONAL LAND EFFECTS AND INCREASING VWS WILL 
QUICKLY CAUSE THE SYSTEM TO WEAKEN, WITH DISSIPATION EXPECTED BY TAU 
120. WITH THE EXPECTION OF CMCX, MODEL GUIDANCE HAS SHIFTED FURTHER 
SOUTH OVER THE PAST 12 HOURS. THE CURRENT FORECAST KEEPS THE TRACK 
ON THE NORTHERN SIDE OF THE MODEL GUIDANCE, MORE IN LINE WITH ECMWF 
AS THE CURRENT TRACK HAS BEEN STEADILY NORTH OF CONSENSUS FOR THE 
PAST FEW MODEL RUNS. BASED ON THE RECENT SHIFTS IN MODEL GUIDANCE 
THE CONFIDENCE IN THE FORECAST TRACK HAS DROPPED TO LOW CONFIDENCE.//
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