WDPS31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (JUDY) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.8S 169.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 307 NM NORTH-NORTHEAST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: WESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) A LARGE
CONSOLIDATING SYSTEM WITH DEEPENING CENTRAL CONVECTION THAT IS
OFFSET NORTHWESTWARD FROM BUT ALSO OBSCURING THE LOW LEVEL
CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON THE 270238Z AMSR2 MICROWAVE LLC FEATURE. THE
INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
HIGHER END OF AGENCY AND AUTOMATED DVORAK ESTIMATES TO REFLECT THE
6-HR IMPROVEMENT. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH
LIGHT TO MODERATE VWS, WARM SST, AND MODERATE RADIAL 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
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 41 KTS AT 270212Z
   CIMSS ADT: 41 KTS AT 270540Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC JUDY WILL 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. 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 321NM BY TAU 120; HOWEVER, GIVEN THE
FORMATIVE STAGE OF THE SYSTEM, 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//
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