WDPS31 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (FIFTEEN) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.7S 167.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 127 NM NORTHEAST OF NOUMEA, NEW CALEDONIA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A HYBRID SYSTEM 
THAT IS EMBEDDED ALONG THE MONSOON TROUGH THAT IS BOUND TO THE SOUTH 
PACIFIC CONVERGENCE ZONE (SPCZ). THE LOW LEVEL CIRCULATION (LLC) IS 
PARTLY EXPOSED UNDER THE LONG SWATH OF CONVECTIVE ACTIVITY ASSOCIATED 
WITH THE SPCZ. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE 
BASED ON THE PARTLY EXPOSED LLC. THE INITIAL INTENSITY OF 45 KTS IS 
ALSO ASSESSED WITH MEDIUM CONFIDENCE BASED ON OVERALL ASSESSMENT OF 
AGENCY AND AUTOMATED INTENSITY ESTIMATES (SEE BELOW) TO REFLECT THE 
MOSTLY SUSTAINED 12-HR CONVECTIVE SIGNATURE. ANALYSIS SHOWS A MARGINAL 
ENVIRONMENT WITH WARM SST AND STRONG POLEWARD OUTFLOW OFFSET BY STRONG 
VWS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   CIMSS ADT: 51 KTS AT 022340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: FORECAST CUT DOWN TO TAU 72 IN
ANTICIPATION OF EARLY DISSIPATION.

FORECAST DISCUSSION: TC 15P WILL CONTINUE TO TRACK EAST-SOUTHEASTWARD 
UNDER THE STEERING STR TO THE NORTH. THE MARGINAL ENVIRONMENT WILL 
MAINTAIN THE CURRENT INTENSITY UP TO TAU 24; AFTERWARD, INCREASING VWS 
AND DRY AIR INTRUSION WILL GRADUALLY ERODE THE SYSTEM TO DISSIPATION BY 
TAU 120, POSSIBLY SOONER, AS IT GETS ABSORBED BY THE SPCZ.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH AN EVEN 
SPREAD TO 125NM; HOWEVER DUE TO THE UNCERTAINTY IN THE FORECAST 
INTENSITY, TYPICAL OF HYBRID SYSTEMS, THERE IS ONLY MEDIUM CONFIDENCE 
TO THE JTWC TRACK AND INTENSITY FORECASTS. 

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