WDPS31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08P (PITA) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.9S 161.5W
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 104 NM WEST-SOUTHWEST OF RAROTONGA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 26 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION BLOWN POLEWARD AND EASTWARD OF THE SHALLOW LOW-LEVEL
CIRCULATION CENTER (LLCC). CLEAR SKIES LIE TO THE SOUTHWEST OF
TROPICAL CYCLONE (TC) 08P, WHICH IS INDICATIVE OF THE DRY AIR
IMPINGING ON THE CIRCULATION CENTER. THE INITIAL POSITION IS PLACED
WITH LOW CONFIDENCE BASED ON THE OBSCURED AND DIFFICULT-TO-IDENTIFY
LLCC IN THE AFOREMENTIONED ANIMATED EIR. THE INITIAL INTENSITY OF
35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AN EARLIER
110816Z METOP-C ASCAT IMAGE REVEALING 30-35KT WINDS IN THE
NORTHEASTERN PERIPHERY OF THE LLCC.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: ON THE SOUTHWESTERN PERIPHERY OF A NEAR
EQUATORIAL RIDGE (NER) TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 35 KTS AT 111140Z
   CIMSS AIDT: 35 KTS AT 111210Z
   CIMSS D-MINT: 47 KTS AT 111142Z
   CIMSS D-PRINT: 48 KTS AT 111240Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG EASTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST IS 24 HOURS SHORTER THAN
THE PREVIOUS WARNING DUE TO THE RAPIDLY DEGRADING NATURE OF TC 08P
AS ENHANCED UPPER-LEVEL WESTERLIES AND DRY AIR HAVE FURTHER ERODED
THE STRUCTURE OF THE SYSTEM.

FORECAST DISCUSSION: TC 08P WILL CONTINUE TO TRACK
EAST-SOUTHEASTWARD FOR THE REMAINDER OF THE FORECAST PERIOD WHILE
DRIVEN BY THE DEEP-LAYER RIDGE TO THE NORTHWEST AND ENHANCED BY A
DEEP-LAYER TROUGH TO THE SOUTH. THE NEARBY JET TO THE SOUTHWEST
WILL CONTINUE TO INDUCE SUBTROPICAL TRANSITION AS TC 08P BECOMES
FURTHER EMBEDDED WITHIN THE JET MAXIMUM. DRY AIR WILL CONTINUE TO
ENTRAIN INTO THE SYSTEM FOR THE REMAINDER OF THE FORECAST, LEADING
TO GRADUAL WEAKENING BELOW 35KTS AS SUBTROPICAL TRANSITION
COMPLETES.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL TRACK EAST-SOUTHEASTWARD FOR THE REMAINDER OF
THE FORECAST PERIOD. THE CROSS-TRACK SPREAD BY TAU 36 IS 75NM. THE
JTWC INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT THE SYSTEM WILL
GRADUALLY WEAKEN FOR THE REMAINDER OF THE FORECAST PERIOD. SOME
MULTI-MODEL CONSENSUS MEMBERS WEAKEN THE SYSTEM RAPIDLY,
SPECIFICALLY COAMPS-TC AND HAFS-A, WHILE OTHER MEMBERS SHOW EITHER
GRADUAL WEAKENING OR AN OVERALL STAGNATION OF THE INTENSITY FOR THE
FIRST 12 HOURS. 

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