WDPS31 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (JUDY) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.5S 169.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 263 NM NORTH-NORTHEAST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A LARGE,
EXPANDING AND CONSOLIDATING SYSTEM WITH DEEPENING CENTRAL CONVECTION 
THAT IS OFFSET NORTHWESTWARD FROM BUT ALSO OBSCURING THE LOW-LEVEL 
CIRCULATION (LLC). THE INITIAL POSITION AND INTENSITY ARE ASSESSED 
WITH HIGH CONFIDENCE BASED ON THE 271003Z ASCAT BULLSEYE PASS. THE 
INITIAL INTENSITY IS ALSO SUPPORTED BY THE HIGHER END OF AGENCY AND 
AUTOMATED DVORAK ESTIMATES AND REFLECTS THE 6-HR IMPROVEMENT. ANALYSIS 
INDICATES A FAVORABLE ENVIRONMENT WITH LIGHT TO MODERATE VWS, WARM 
SST, AND STRONG EQUATORIAL OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   PHFO: T3.5 - 55 KTS
   NFFN: T3.0 - 45 KTS
   CIMSS SATCON: 51 KTS AT 270937Z
   CIMSS ADT: 45 KTS AT 270830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC JUDY WILL CONTINUE TO TRACK SOUTHWESTWARD,
SOUTHWARD, THEN ACCELERATE SOUTHEASTWARD AS IT ROUNDS THE WESTERN
EDGE OF THE STEERING STR. THE FAVORABLE ENVIRONMENT WILL FUEL A
STEADY INTENSIFICATION TO A PEAK OF 80KTS BY TAU 48, ENHANCED BY
IMPROVED POLEWARD OUTFLOW AHEAD OF A SHORTWAVE TROUGH APPROACHING
FROM THE SOUTHWEST. AFTERWARD, INCREASING VWS AND COOLING SST WILL
GRADUALLY WEAKEN THE CYCLONE, AND BY TAU 120, WILL BE REDUCED TO
45KTS AS IT PASSES NORTHEAST OF NEW ZEALAND. CONCURRENTLY BY TAU
96, THE SYSTEM WILL BEGIN SUBTROPICAL TRANSITION AND BY TAU 120
WILL TRANSFORM INTO A SUBTROPICAL LOW. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH AN
EVEN AND GRADUAL SPREAD TO 346NM BY TAU 120; HOWEVER, GIVEN THE
FORMATIVE STAGE OF THE SYSTEM AND UNCERTAINTIES ASSOCIATED WITH
SUBTROPICAL TRANSITION, THERE IS ONLY MEDIUM CONFIDENCE TO 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//
NNNN