WDXS31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (VERNON) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.5S 93.3E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 250 NM SOUTHWEST OF COCOS ISLANDS,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 14S IS UNDERGOING A PERIOD OF VERY RAPID INTENSIFICATION, WITH
THE INITIAL INTENSITY INCREASING FROM 45 KNOTS SIX HOURS AGO TO 70
KNOTS ON THIS WARNING. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS A VERY COMPACT SYSTEM WITH A WELL DEFINED PINHOLE
EYE HAVING RAPIDLY DEVELOPED SINCE THE 250900Z HOUR. AT 1200Z THE
EYE MEASURED SLIGHTLY LESS THAN 10NM WIDE. EYE TEMPERATURES WERE
STILL VERY COLD, BUT CLOUD TOP TEMPERATURES REACHED AS LOW AS -86C
IN THE STRONGEST HOT TOWERS SURROUNDING THE EYE. 250950Z GPM 37GHZ
AND 89GHZ MICROWAVE IMAGERY DEPICTED THE EYE TO GOOD EFFECT,
SURROUNDED BY A SOLID BAND OF DEEP CONVECTION. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE 10NM EYE IN THE EIR AND
AN EXTRAPOLATION OF THE MICROWAVE EYE FEATURE. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, PRIMARILY BASED ON
FORECAST ASSESSMENT OF THE STRUCTURE AND APPEARANCE OF THE SYSTEM.
THE APRF ESTIMATE OF T4.0 IS CLOSER TO REALITY BUT LIKELY TOO LOW
AS IS THE PGTW T3.5 AND THE ADT WHICH IS MISSING THE PINHOLE EYE
FEATURE ALTOGETHER. THE SYSTEM IS INTENSIFYING UNDER VERY FAVORABLE
CONDITIONS WITH LOW SHEAR, VERY WARM, HIGH OHC WATERS AND A SMALL
POINT SOURCE OVER TOP OF THE SYSTEM PROVIDING GOOD LOCALIZED RADIAL
OUTFLOW AND A WEAK POLEWARD OUTFLOW CHANNEL.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   APRF: T4.0 - 65 KTS
   CIMSS ADT: 49 KTS AT 251140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: RADIAL OUTFLOW IS VERY LIMITED TO THE DIRECT
VICINITY OF THE CORE OF THE SYSTEM, WITH MODERATE POLEWARD OUTFLOW.


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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST PHILOSOPHY, HOWEVER DUE TO THE RECENT RAPID
INTENSIFICATION, THIS FORECAST IS BEING ISSUED OFF-CYCLE TO CAPTURE 
INTENSIFICATION TREND AND ADJUST THE PEAK INTENSITY FORECAST. 

FORECAST DISCUSSION: TC 14S WILL CONTINUE TRACKING WEST-SOUTHWEST
THROUGH TAU 12 ALONG THE NORTHERN SIDE OF THE STR. AFTER THIS POINT
THE FORECAST GETS INTERESTING, AS TC 14S WILL BEGIN BINARY
INTERACTION WITH INVEST 93S, CURRENTLY LOCATED APPROXIMATELY 300NM
TO THE NORTHWEST. INVEST 93S IS TWO DEGREES EQUATORWARD OF TC 14S,
AND THUS WILL MOVE TO A POSITION TO THE NORTH OF TC 14S AS IT
TRACKS EASTWARD AND SLOWLY SPIRALS IN CLOSER TO TC 14S. AS 93S
PASSES TO THE NORTH, TC 14S WILL BEGIN TO TRACK TOWARDS THE
NORTHWEST AS THE TWO SYSTEMS BEGIN TO FUJIWARA ABOUT ONE ANOTHER.
TC 14S WILL COMPLETE A CLOCKWISE LOOP AND THE TWO SYSTEMS ARE
EXPECTED TO MERGE INTO ONE LARGER SYSTEM AROUND TAU 48. AS THIS IS
OCCURRING, FAR TO THE SOUTH A MID-LATITUDE TROUGH WILL ERODE THE
STEERING RIDGE FROM WEST TO EAST, ALLOWING FOR TC 14S TO TURN
POLEWARD AFTER TAU 48, ACCELERATING SOUTH-SOUTHWEST THROUGH THE
REMAINDER OF THE FORECAST. FROM AN INTENSIFICATION STANDPOINT, THE
SYSTEM IS COCOONED WITHIN A VERY FAVORABLE ENVIRONMENT, BUT FOR
ONLY ABOUT ANOTHER 24 HOURS, WHEN THE CORE WILL START TO BE
DISRUPTED BY THE BINARY INTERACTION AND MERGER WITH 93S. THUS THE
SYSTEM IS FORECAST TO INCREASE TO 100 KNOTS BY TAU 24, THEN LEVEL
OFF AS IT MERGES WITH 93S, FOLLOWED BY A BRIEF SPURT OF
REINTENSIFICATION TO A PEAK OF 105 KNOTS BY TAU 48. AFTER TAU 72
THE SYSTEM WILL ENCOUNTER INCREASING VWS, WHICH WILL INITIATE A
STEADY WEAKENING TREND THROUGH THE REMAINDER OF THE FORECAST
PERIOD. 

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE GUIDANCE HAS COME INTO
A BIT BETTER AGREEMENT SINCE THE PREVIOUS FORECAST. UKMET AND GFS
CONTINUE TO MARK THE EASTERN AND WESTERN BOUNDARIES RESPECTIVELY,
WITH ALL TRACKERS SUPPORTING TO VARYING DEGREES THE SLOW, LOOPING
MOTION FROM TAU 24 TO 48. THE JTWC FORECAST REMAINS CONSISTENT WITH
THE PREVIOUS FORECAST, AND TRACKS THE CONSENSUS MEAN THROUGH TAU
36, THEN HEDGES TOWARDS THE WESTERN EDGE OF THE ENVELOPE
THEREAFTER. DUE TO THE HIGH UNCERTAINTY ASSOCIATED WITH THE BINARY
INTERACTION, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.
INTENSITY GUIDANCE IS MIXED, WITH THE HWRF AND COAMPS SUGGESTING
NEAR-TERM WEAKENING TO 45 KNOTS FOLLOWED BY INTENSIFICATION AFTER
MERGER TO A SECOND PEAK OF 95 KNOTS BY TAU 96. MEANWHILE THE DECAY
SHIPS SUGGESTS STEADY INTENSIFICATION PEAKING AT AROUND 95 KNOTS.
ADDITIONALLY THE RAPID INTENSIFICATION AIDS CONTINUE TO TRIGGER
WITH THIS RUN, WITH RIPA PEAKING AT 125 KNOTS AT TAU 48. THE JTWC
FORECAST FOLLOWS RIPA THROUGH TAU 24, BUT THEN SHIFTS TO ROUGHLY
APPROXIMATE THE DECAY SHIPS AND HWRF SOLUTIONS THROUGH THE
REMAINDER OF THE FORECAST. CONFIDENCE IS LOW IN LIGHT OF THE RAPID
INTENSIFICATION TRENDS, POSSIBLE ERC AND THE ULTIMATE IMPACT OF THE
BINARY INTERACTION AND MERGER.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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