WDPN33 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (NANGKA) WARNING NR 
05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 11W (NANGKA), LOCATED APPROXIMATELY 147 NM WEST OF
UTIRIK, HAS TRACKED WESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. 
ANIMATED EIR LOOP REVEALS GOOD BANDING WRAPPING TIGHTLY INTO A CLOUD 
FILLED LLCC. A 041037Z AMSU SHOWS GOOD CONVECTION WITH THE DEEPEST 
CONVECTION ON THE WESTERN SIDE OF THE SYSTEM AND A FORMATIVE 
MICROWAVE EYE. THE 040945Z ASCAT PASS SHOWS A FAIRLY SYMMETRIC 
STRUCTURE WITH WINDS OF AT LEAST 45 KNOTS. THE POSITION AND 
INTENSITY ARE BASED ON THE ABOVE MENTIONED SATELLITE IMAGES WITH 
GOOD CONFIDENCE. THE UPPER LEVEL ENVIRONMENT CONTINUES TO BE 
FAVORABLE WITH LOW VWS AND SEEMINGLY RADIAL OUTFLOW. TS 11W IS 
CURRENTLY TRACKING NORTHWEST ALONG THE SOUTHERN PERIPHERY OF THE STR.
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC 
REASONING MESSAGE.
   B. TS NANGKA WILL CONTINUE TO TRACK WEST-NORTHWEST ALONG THE 
SOUTHERN PERIPHERY OF THE STR THROUGH TAU 36. AS THE STR BEGINS TO 
BREAK DOWN AND TRACK TO THE EAST, EXPECT A POLEWARD SHIFT IN THE 
TRACK OF THE STORM. OVER THE NEXT 12 HOURS, EXPECT TS NANGKA TO 
RAPIDLY INCREASE IN INTENSITY TO TYPHOON STRENGTH WITH A STEADY 
INCREASE IN INTENSITY THROUGH TAU 72 DUE TO THE ENVIRONMENT 
REMAINING FAVORABLE.
   C. BEYOND TAU 72, TS 11W WILL TAKE ON A MORE NORTHWEST TRACK AS 
THE STR MOVES TO THE EAST, ALLOWING TS 11W TO GAIN LATITUDE. THE 
UPPER LEVELS AT THIS TIME WILL SLIGHTLY IMPEDE DEVELOPMENT OF THE 
SYSTEM, FORCING TS NANGKA TO MAINTAIN ITS INTENSITY THROUGH THE END 
OF THE FORECAST PERIOD. AS MODEL GUIDANCE REMAINS IN TIGHT 
AGREEMENT, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST WHICH IS 
LAID CLOSE TO THE MULTI-MODEL CONSENSUS.//
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