WDPS31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08P (PITA) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.4S 164.2W
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 246 NM WEST OF RAROTONGA
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 35 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
ELONGATED LOW-LEVEL BANDING IN THE NORTHWESTERN QUADRANT OF THE
CIRCULATION WITH DEEP CONVECTION OBSCURING THE REMAINDER OF
TROPICAL CYCLONE (TC) 08P TO THE SOUTHEAST. THE SYSTEM EMBEDDED
WITHIN THE SOUTH PACIFIC CONVERGENCE ZONE (SPCZ) IS COMBATTING HIGH 
VERTICAL WIND SHEAR TO REMAIN 40KTS. AN 110512Z F-16 SSMIS COLOR-
ENHANCED 91GHZ MICROWAVE IMAGE HIGHLIGHTS THE AFOREMENTIONED 
CONVECTIVE BURST AND ASSOCIATED LOW-LEVEL BANDING AROUND THE 
CIRCULATION CENTER. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED MSI AND MICROWAVE 
IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON PERSISTENCE ALONGSIDE THE AGENCY AND OBJECTIVE 
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A NEAR EQUATORIAL RIDGE (NER) TO THE
NORTHEAST 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 41 KTS AT 110540Z
   CIMSS AIDT: 36 KTS AT 0740Z
   CIMSS D-PRINT: 50 KTS AT 110740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE EASTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TC 08P WILL CONTINUE TO TRACK EAST-SOUTHEASTWARD 
UNDER THE STEERING INFLUENCE OF THE NORTHEASTERN STR FOR THE NEXT 48 
HOURS. WHILE THE SYSTEM WILL CONTINUE TO BE FUELED BY WARM SEA 
SURFACE TEMPERATURES AND STRONG UPPER-LEVEL DIVERGENCE FOR THE 
REMAINDER OF THE FORECAST PERIOD, THE SYSTEM WILL BE HINDERED BY HIGH 
VWS THAT WILL REMAIN ABOVE AN UNFAVORABLE 20KTS. A JET MAX 
APPROACHING FROM THE SOUTHWEST WILL CAUSE SHALLOWING OF TC 08P AND 
BEGIN TO CAUSE SUBTROPICAL TRANSITION BY TAU 36. TC 08P WILL BECOME 
FULLY SUBTROPICAL BY TAU 48.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 24, BUT BEGINS TO LOSE THE VORTEX BY TAU 36, CAUSING
MODERATE BIFURCATION BY TAU 48. GFS INDICATES A GENERAL EAST-
NORTHEASTWARD TRACK, WHILE THE MAJORITY OF THE CONSENSUS DEPICTS AN 
EAST-SOUTHEASTWARD TRACK. THE INTENSITY GUIDANCE AGREES ON STEADY 
WEAKENING THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD. 

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