WDPS31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 26P (TWENTYSIX) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9S 169.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 178 NM NORTH-NORTHEAST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A MEDIUM
SIZED SYSTEM WITH DISORGANIZED DEEP FLARING CENTRAL CONVECTION THAT
IS SHEARED FROM AN EXPOSED LOW LEVEL CIRCULATION (LLC). HOWEVER, A 
FRESH BALL OF CONVECTION DUE SOUTH OF THE THE LLC HAS BEGUN TO GROW 
AND EXPAND INTO THE LLC OVER THE LAST FEW HOURS. THE MAIN FORMATIVE 
RAIN BAND IS FEEDING IN FROM THE NORTHEAST. THE EIR LOOP ALSO SHOWS 
TRANSVERSE BANDING ALONG THE SOUTHERN PERIPHERY, AN INDICATION OF 
STRONG VERTICAL WIND SHEAR. THE INITIAL POSITION AND INTENSITY ARE 
EXTRAPOLATED WITH HIGH CONFIDENCE FROM THE 181052Z ASCAT BULLSEYE 
PASS WITH THE STRONGEST WIND BARBS ALONG THE SOUTHWEST QUADRANT 
UNDER THE FLARING CONVECTION.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 26P IS EXPECTED TO CONTINUE SOUTHWESTWARD
ALONG THE NORTHWEST PERIPHERY OF THE STR AND TRACK OVER THE
NORTHERN ISLANDS OF VANUATU OVER THE NEXT 24HRS. AFTER TAU 72, IT
WILL ROUND THE STR AXIS AND RECURVE SOUTHEASTWARD TOWARD NEW
CALEDONIA. THE MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL WEAK
INTENSIFICATION TO 40KTS AT TAUS 12-36. AFTERWARD, INCREASING VWS
WILL GRADUALLY ERODE THE SYSTEM TO DISSIPATION BY TAU 96, POSSIBLY
SOONER.  

MODEL DISCUSSION: NUMERICAL MODELS WIDELY SPREAD OUT TO OVER 310NM
BY TAU 96 BUT ARE IN BROAD AGREEMENT WITH THE POLEWARD AND
RECURVING TRACK WITH AFUM ON THE RIGHT AND NAVGEM ON THE LEFT
MARGIN OF THE MODEL ENVELOPE. IN VIEW OF THIS, THERE IS MEDIUM
CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS.  

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