WDPN32 PGTW 190300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (MAN-YI) WARNING NR 
041//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.5N 114.0E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 228 NM SOUTH OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SMALL
PATCH OF DEEP CONVECTION CONFINED TO THE NORTHERN PORTION OF A
PARTIALLY EXPOSED LOW-LEVEL CIRCULATION. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON MULTI-AGENCY SATELLITE FIXES
AND AN 182158Z PARTIAL WSF-M MICROWAVE SATELLITE PASS. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE FAVORING 
AUTOMATED FIX ESTIMATES RANGING FROM 32 KTS (CIMSS D-PRINT) TO 41 KTS 
(CIMSS ADT). TROPICAL STORM (TS) 25W IS INTERACTING DIRECTLY WITH A
NORTHEASTERLY COLD SURGE TO THE WEST, USHERING DRY AIR INTO THE
SYSTEM AND INDUCING INCREASING VERTICAL WIND SHEAR WITH THE
PREVAILING ENVIRONMENTAL LOW-LEVEL FLOW TOWARD THE SOUTHWEST AND
UPPER-LEVEL FLOW TOWARD THE NORTHEAST.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) EXTENSION TO
THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS ADT: 41 KTS AT 182330Z
   CIMSS AIDT: 36 KTS AT 182330Z
   CIMSS D-PRINT: 32 KTS AT 182330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: PERSISTENT VERTICAL WIND SHEAR AND DRY AIR
ENTRAINMENT WILL PUT A QUICK END TO TS 25W OVER THE NEXT 24 HOURS.
AS THE LOW-LEVEL CIRCULATION BECOMES FULLY DECOUPLED FROM ASSOCIATED 
CONVECTION IT WILL TURN WEST-SOUTHWESTWARD FOLLOWING THE COLD SURGE 
FLOW. FULL DISSIPATION OF THE VORTEX IS LIKELY AFTER THE FORECAST 
PERIOD, MAKING IT UNLIKELY THAT REMNANT CIRCULATION WILL MAKE LANDFALL 
AT ANY POINT.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
REGARDING THE OVERALL FORECAST SCENARIO, DIRECTION OF MOTION AND
INTENSITY FORECAST, INCLUDING DISSIPATION OF THE VORTEX. BOTH THE
TRACK AND INTENSITY FORECASTS LIE CLOSE TO THE MULTI-MODEL
CONSENSUS AND TO THE PREVIOUS JTWC FORECAST, ALBEIT WITH A SLIGHTLY
FASTER DISSIPATION TIMELINE, WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH//
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