WDPS31 PGTW 141500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (THIRTY) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.4S 168.4E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 78 NM NORTH OF PORT VILA, VANUATU
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 30P WITH LARGE SWATHS OF CONVECTION OBSCURING THE LOW-LEVEL
CIRCULATION CENTER (LLCC) THAT IS ASSESSED TO BE NEARLY DIRECTLY
OVER THE ISLANDS OF VANUATU AT THIS TIME. VAST CONVECTIVE BANDING
CAN BE SEEN TRAILING FAR OFF TO THE NORTH AND SOUTH OF THE CENTER.
A 141028Z METOP-B ASCAT IMAGE REVEALED THE BROAD CIRCULATION WITH
35-40 KTS CONFINED TO THE EASTERN SEMICIRCLE. ENVIRONMENTAL
ANALYSIS INDICATES THAT 30P IS IN A FAVORABLE ENVIRONMENT
CHARACTERIZED BY STRONG POLEWARD AND EQUATORWARD OUTFLOW, LOW
(10-15 KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE
TEMPERATURES. THE MAIN HINDERING FACTOR FOR THE SYSTEM WILL BE THE
ASYMMETRICAL AND BROAD WIND FIELD. THE INITIAL POSITION, INTENSITY,
AND WIND RADII ARE ALL PLACED WITH HIGH CONFIDENCE BASED ON THE
MENTIONED METOP-B ASCAT IMAGE.

INITIAL WIND RADII BASIS: 141028Z METOP-B ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 41 KTS AT 141210Z
   CIMSS AIDT: 31 KTS AT 141210Z
   CIMSS PRINT: 38 KTS AT 141140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND 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 30P IS FORECAST TO TRACK SOUTHWARD, ALONG
THE WESTERN PERIPHERY OF THE STR THROUGHOUT THE FORECAST PERIOD
WITH FASTER THAN AVERAGE TRACK SPEEDS. THE SYSTEM IS EXPECTED TO
STEADILY INTENSIFY OVER THE NEXT 36 HOURS DUE TO THE FAVORABLE
ENVIRONMENT, PARTICULARLY THE POLEWARD OUTFLOW. NEAR TAU 36, AN
INCOMING LONG WAVE TROUGH WILL ENVELOP THE SYSTEM AND CAUSE THE
SYSTEM TO COMPLETE SUBTROPICAL TRANSITION NEAR TAU 36 AND THEN
EXTRATROPICAL TRANSITION BY TAU 60. THE EXPANSIVE COLD-CORE LOW
WILL THEN PLANT ITSELF TO THE NORTHWEST OF NEW ZEALAND.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH A 175 NM CROSS-TRACK SPREAD AT TAU 36 AND MINIMAL
ALONG-TRACK SPREAD BETWEEN TRACKERS. THE JTWC TRACK FORECAST IS
PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH ALL MODELS
SUGGESTING INTENSIFICATION TO 55-65 KTS AT TAU 36. THEREFORE, THE
JTWC INTENSITY FORECAST IS ALSO PLACED WITH HIGH CONFIDENCE.

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