WDPN31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TRAMI) WARNING 
NR 031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.7N 107.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 29 NM SOUTHWEST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 04 KTS

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL DEPRESSION
22W (TRAMI) AFTER IT MADE A U-TURN AND IS TRACKING BACK SLOWLY 
TOWARDS COASTAL VIETNAM AND THE SOUTH CHINA NEAR THE CITY OF DA NANG. 
THE INITIAL POSITION IS THEREFORE PLACED WITH HIGH CONFIDENCE. THE 
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON 
LACK OF DEVELOPING CONVECTION, WHILE THE SYSTEM TRANSITS OVER LAND, 
OFFSET BY REMAINING STRUCTURAL INTEGRITY OF THE CIRCULATION.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: COMPETING STEERING INFLUENCE OF
SUBTROPICAL RIDGES TO THE WEST AND TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: OVER LAND
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: DESPITE THE LACK OF WARM WATER AND FRICTIONAL
EFFECTS OF LAND INTERACTION, TROPICAL DEPRESSION 22W MANAGED TO
MAINTAIN AN ORGANIZED CIRCULATION, WITH THE HELP OF VERY LOW VERTICAL
WIND SHEAR (VWS). THE SYSTEM INTENSITY IS CURRENTLY ASSESSED TO BE
AT 30 KTS, HOWEVER AS SOON AS IT MOVES OVER WATER WITHIN THE NEXT
24 HOURS, IT WILL ENCOUNTER AN INCREASINGLY STRONGER VWS FROM THE
WEST AND SOUTHWEST. GIVEN THE MARGINALLY UNFAVORABLE CONDITIONS,
TD 22W IS EXPECTED TO BEGIN WEAKENING SHORTLY AFTER AND COMPLETE
DISSIPATION BY THE END OF THE FORECAST PERIOD. 

MODEL DISCUSSION: MODEL GUIDANCE IS INCONSISTENT IN TERMS OF BOTH
TRACK AND DISSIPATION TIMELINE, WITH SOME MODELS (ECMWF ENSEMBLE)
MOVING THE SYSTEM NORTH, RIGHT AFTER ER-EMERGING OVER WATER, WHILE
OTHERS (GFS) PREDICTING A SOUTHWESTWARD TRACK. THERE IS A
SIGNIFICANT DIFFERENCE IN VERTICAL WIND SHEAR VALUES BETWEEN THOSE
TWO APPROACHES. ADDITIONALLY, SEA SURFACE TEMPERATURES ARE ALSO 2-3
DEGREES CELSIUS COLDER CLOSER TO HAINAN, THAN THEY ARE, IF THE
SYSTEM WERE TO TRACK SOUTHWESTWARD. THEREFORE, BOTH TRACK AND
INTENSITY ARE ASSESSED WITH LOW CONFIDENCE, WITH THE TRACK PLACED
CLOSE TO THE MULTI-MODEL CONSENSUS, WITHOUT THE OUTLIERS, AND THE
INTENSITY GUIDANCE SLIGHTLY LOWER THAN THE CONSENSUS. 

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