WDPN31 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 
029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.4N 107.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 63 NM SOUTHWEST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 07 KTS

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND RADAR IMAGERY 
DEPICT RAPIDLY DETERIORATING CONVECTION, PRIMARILY OVER THE WESTERN 
SEMICIRCLE, WITH A BROAD BUT DEFINED LOW-LEVEL CIRCULATION CENTER 
(LLCC). A 271136Z GMI 89GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS THE 
BULK OF THE DEEP CONVECTION DISPLACED OVER THE WESTERN SEMICIRCLE DUE 
TO MODERATE TO HIGH EASTERLY VERTICAL WIND SHEAR. THE INITIAL POSITION 
IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE EIR IMAGERY. THE INITIAL 
INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A 
BLEND OF THE RJTD DATA-T ESTIMATE OF T2.0 (30 KNOTS) AND THEIR CURRENT 
INTENSITY ESTIMATE OF 3.0 (45 KNOTS) REFLECTING THE RAPIDLY WEAKENING 
CONVECTIVE STRUCTURE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WEAK, COMPETING STEERING ENVIRONMENT WITH 
A SUBTROPICAL RIDGE (STR) TO THE WEST AND NORTHEAST, AND A SWATH OF 
WESTERLIES TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T3.0 - 45 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: OVER LAND
   OUTFLOW: MODERATE WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TS 22W IS LOCATED WITHIN A REGION OF WEAK 
STEERING AND IS EXPECTED TO MAINTAIN QUASI-STATIONARY TRACK MOTION
THROUGH TAU 24. STEADY WEAKENING WILL OCCUR THROUGH THIS PERIOD DUE
TO INTERACTION WITH LAND AND PERSISTENT EASTERLY VERTICAL WIND SHEAR. 
AFTER TAU 24, THE SYSTEM IS FORECAST TO DRIFT EASTWARD ALONG THE 
NORTHERN PERIPHERY OF THE LOW-LEVEL WESTERLIES AND SHOULD MOVE BACK 
OVER WATER BY THE TAU 36 TO TAU 48 PERIOD. THE SYSTEM WILL LIKELY 
DISSIPATE BUT COULD LINGER NEAR TROPICAL DEPRESSION STRENGTH.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE SHOWS A SQUASHED SPIDER
PATTERN WITH DETERMINISTIC GUIDANCE GENERALLY INDICATING A HIGHLY
UNCERTAIN, ERRATIC TRACK MOTION THROUGH THE FORECAST PERIOD. ALL
GUIDANCE EVENTUALLY BRINGS THE SYSTEM BACK OVER WATER BUT THE EXACT
TRACK MOTION VARIES CONSIDERABLY. THE MOST RECENT EPS AND GEFS
PROBABILISTIC GUIDANCE ALSO SHOWS A SIMILAR TRACK PATTERN WITH THE
BULK OF SOLUTIONS TRACKING THE SYSTEM BACK OVER WATER AS A WEAK
TROPICAL DEPRESSION OR TROPICAL DISTURBANCE.   

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