WDPS31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (FIFTEEN) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.0S 168.0E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 125 NM EAST-NORTHEAST OF NOUMEA, NEW
CALEDONIA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 15P WITH AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) AND
CONVECTION BEING SHEARED OFF TO THE SOUTHEAST. ENVIRONMENTAL
ANALYSIS INDICATES THAT 15P IS IN AN UNFAVORABLE ENVIRONMENT
CHARACTERIZED BY STRONG POLEWARD OUTFLOW AND WARM SEA SURFACE
TEMPERATURES, STRONGLY OFFSET BY HIGH (30-35 KTS) WESTERLY VERTICAL
WIND SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE EXPOSED LLCC IN THE ANIMATED EIR IMAGERY. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   CIMSS SATCON: 40 KTS AT 031200Z
   CIMSS ADT: 34 KTS AT 031200Z
   CIMS DPRINT: 39 KTS AT 031200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30-35 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT ALONG THE WESTERN PERIPHERY.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: 15P IS FORECAST TO TRACK SOUTHEASTWARD, ALONG
THE SOUTHWESTERN PERIPHERY OF THE STR THROUGHOUT THE FORECAST
PERIOD. VERTICAL WIND SHEAR IS EXPECTED TO RISE ABOVE 40 KTS AROUND
TAU 24 AND DRY AIR ENTRAINMENT WILL ONLY WORSEN. THESE TWO FACTORS
WILL CAUSE 15P TO WEAKEN BELOW 35 KTS BY TAU 48, POSSIBLY SOONER. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN AGREEMENT ON A
SOUTHEASTWARD TRACK, WITH A 130 NM CROSS-TRACK SPREAD AT TAU 72.
THE JTWC TRACK FORECAST IS PLACED CLOSE TO CONSENSUS WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH THE
EXCEPTION OF COAMPS-TC, WHICH HAS THE SYSTEM STEADILY INTENSIFYING
RATHER THAN WEAKENING. THE JTWC INTENSITY FORECAST IS PLACED CLOSE
TO THE MAIN GROUPING OF GUIDANCE WITH MEDIUM CONFIDENCE, DUE TO THE
POSSIBILITY OF AN EARLY DISSIPATION.

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