WDPN32 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (DOLPHIN) WARNING 
NR 20//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 07W (DOLPHIN), LOCATED APPROXIMATELY 464 NM 
EAST-NORTHEAST OF CHUUK, HAS TRACKED NORTHWESTWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY 
DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH 
DEEPENING ALBEIT BROKEN CONVECTIVE BANDING SHEARED TO THE WEST. AN 
111041Z GMI 36GHZ MICROWAVE IMAGE SHOWS SPIRAL BANDING BEGINNING TO 
WRAP AROUND THE WESTERN PERIPHERY WITH A PARTIALLY CLOSED MICROWAVE 
EYE FEATURE THAT SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. 
THE INITIAL INTENSITY HAS BEEN INCREASED TO 45 KNOTS TO REFLECT THE 
IMPROVED STRUCTURE OF THE SYSTEM AND IS SUPPORTED BY AN ASSESSMENT 
OF DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES. UPPER LEVEL 
CONDITIONS REMAIN MARGINAL WITH EASTERLY DIFFLUENT FLOW ALOFT AND 
MODERATE (20 TO 25 KNOTS) VERTICAL WIND SHEAR (VWS); HOWEVER, THE 
STORM MOTION IS NOW IN-PHASE WITH THE VWS VECTOR, REDUCING THE 
OVERALL IMPACTS. TS DOLPHIN HAS STARTED TO ACCELERATE WEST-
NORTHWESTWARD UNDER THE INFLUENCE OF THE BUILDING SUB-TROPICAL RIDGE 
(STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 07W WILL CONTINUE TO TURN TO A MORE WESTWARD TRAJECTORY 
OVER THE NEXT 06 HOURS AS THE STEERING STR CONTINUES TO BUILD TO THE 
NORTH. UPPER LEVEL CONDITIONS WILL REMAIN MOSTLY UNCHANGED, LEADING 
TO A SLIGHT INTENSIFICATION. BEYOND TAU 36, AN IMPROVING 
ENVIRONMENT, WITH REDUCED VWS (05 TO 10 KNOTS) AND AN INCREASING 
POLEWARD OUTFLOW CHANNEL, WILL LEAD TO AN INCREASED INTENSIFICATION 
RATE.
   C. AFTER TAU 72, TS DOLPHIN WILL TRACK WEST-NORTHWESTWARD AS IT 
MOVES JUST DOWNSTREAM FROM THE STEERING STR. BY TAU 96, ANOTHER 
APPROACHING MID-LATITUDE TROUGH WILL CAUSE THE STEERING STR TO 
WEAKEN AGAIN, ALLOWING TS 07W TO TURN SLIGHTLY POLEWARD TOWARDS A 
BREAK IN THE RIDGE. ENVIRONMENTAL CONDITIONS WILL BECOME MORE 
FAVORABLE WITH AN ENHANCED UPPER LEVEL OUTFLOW AND SEA SURFACE 
TEMPERATURES ABOVE 28 CELSIUS, SUPPORTING FURTHER INTENSIFICATION. 
DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE 
IN THE JTWC FORECAST.//
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