WDPN31 PGTW 252100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 
022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.2N 115.3E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 312 NM SOUTH-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
IMPROVED CONVECTIVE PLUME AND COLD COVER OVER TS 22W WITH SIGNS OF
AN ATTEMPT AT RADIAL OUTFLOW BUT EVIDENCE OF SHEAR ON THE NORTHEAST
SIDE. THE EQUATORWARD OUTFLOW REMAINS VIGOROUS DUE TO SUPPORT FROM
THE TROPICAL EASTERLY JET. THE INITIAL POSITION IS PLACED WITH LOW
CONFIDENCE BASED ON EXTRAPOLATION FROM AN EARLIER 231250Z ASCAT UHR
BULLSEYE IMAGE AND A 231404Z AMSU-B 89 GHZ MICROWAVE IMAGE SHOWING
CURVED BANDING AROUND THE WESTERN AND SOUTHERN PERIPHERIES. THE
INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON AGENCY SUBJECTIVE DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: HIGH PRESSURE SYSTEM CENTERED OVER
NORTHERN MYANMAR

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 55 KTS AT 251447Z
   CIMSS ADT: 35 KTS AT 251730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 27-29 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM 22W IS ENJOYING ITS PEAK NOW
AND IS EXPECTED TO BEGIN TO DECAY GOING FORWARD DUE TO THE
UNFAVORABLE AMOUNTS OF SHEAR. DESPITE THE GRADUAL WEAKENING, THE
LOW LEVEL CIRCULATION IS EXPECTED TO HOLD TOGETHER THROUGH THE END
OF THE FORECAST PERIOD AND TRACK GENERALLY WESTWARD UNTIL IT RUNS
INTO RIDGING OVER VIETNAM. THE RIDGE WILL BLOCK THE SYSTEM FROM
MAKING LANDFALL AND WILL TURN IT SHARPLY SOUTH, AFTER WHICH RIDGING
OVER THE PHILIPPINES WILL ASSUME CONTROL AS THE DOMINANT STEERING
MECHANISM. UNCERTAINTY REGARDING FURTHER STRENGTHENING AT THE END
OF THE FORECAST PERIOD HAVE DIMINISHED DUE TO A LIKELY
DECAPITATION SCENARIO IN THE FACE OF HOSTILE VERTICAL WIND SHEAR.
THEREFORE, THE SYSTEM IS EXPECTED TO BEGIN DISSIPATION OVER WATER
AT TAU 120.

MODEL DISCUSSION: THE MODELS SHARE POOR AGREEMENT AND LITTLE
RUN-TO-RUN CONSISTENCY REGARDING THE TRACK AND POINT AT WHICH THE
SOUTHWARD TURN CAN BE EXPECTED. DETERMINISTIC GUIDANCE IS OBLIVIOUS
TO THE EXPECTED SOUTHWARD TURN AND SHOWS THE SYSTEM CONTINUING
WESTWARD INTO THE VIETNAM COAST. INTENSITY GUIDANCE HOLDS MUCH
BETTER AGREEMENT THAT FURTHER STRENGTHENING IS UNLIKELY, AND A
GRADUAL DECLINE IN WINDSPEEDS CAN BE EXPECTED GOING FORWARD.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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