WDXS31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (DUDZAI) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.6S 77.8E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 649 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 14S (DUDZAI) CONTINUING TO RAPIDLY INTENSIFY. THE EYE HAS
CLEARED OUT, SIGNIFICANTLY WARMED, AND BECOME MUCH MORE SYMMETRIC
OVER THE PAST 6 HOURS. THE CENTRAL DENSE OVERCAST (CDO) HAS ALSO
CONTRACTED INTO A SMALL RING WITH VERY COLD (-75 C) CLOUD TOPS
ENTIRELY SURROUNDING THE EYEWALL. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE DEFINED EYE IN ANIMATED MSI. THE
INITIAL INTENSITY OF 100 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A COMBINATION OF THE AGENCY DVORAK FIXES AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW. THE INITAL WIND RADII ARE PLACED
WITH HIGH CONFIDENCE BASED ON A TIMELY 120406Z METOP-B ASCAT
BULLSEYE PASS. ENVIRONMENTAL ANALYSIS INDICATES THAT 14S IS IN A
HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD
OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (27-28
C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: 120406Z METOP-B ASCAT SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   DEMS: T5.0 - 90 KTS
   FMEE: T5.5 - 102 KTS
   FIMP: T6.0 - 115 KTS
   CIMSS ADT: 94 KTS AT 120630Z
   CIMSS AIDT: 96 KTS AT 120630Z
   CIMSS D-PRINT: 105 KTS AT 120630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: NEAR-TERM INTENSITY FORECAST HAS
INCREASED DUE TO CONTINUED RAPID INTENSIFICATION.

FORECAST DISCUSSION: TC 14S IS FORECAST TRACK VERY SLOWLY SOUTHWARD
THROUGH TAU 24 AS IT ENTERS A COMPETING STEERING ENVIRONMENT.  NEAR
TAU 24, 14S IS EXPECTED TO INITIATE A SHARP WESTWARD TURN AS THE
STEERING MECHANISM SHIFTS TO A BUILDING STR TO THE SOUTHWEST. 14S
WILL THEN CONTINUE ON A GENERALLY WESTWARD TRACK, ALONG THE
NORTHERN EXTENT OF THE STR, THROUGH TAU 96. AFTER TAU 96, THE
SYSTEM WILL BEGIN TO ROUND THE NORTHWESTERN PERIPHERY OF THE STR,
CAUSING A SOUTHWESTWARD TRACK THROUGH THE REMAINDER OF THE FORECAST
PERIOD. IN TERMS OF INTENSITY, 14S IS FORECAST TO CONTINUE
INTENSIFYING OVER THE NEXT 12 HOURS DUE TO THE HIGHLY FAVORABLE
ENVIRONMENT. THE PEAK INTENSITY IS CURRENTLY FORECAST TO BE 110
KTS, BUT BASED ON THE APPEARANCE AT 120800Z, THAT WILL LIKELY BE
TOO LOW. AFTER TAU 12, THE SYSTEM IS EXPECTED TO INTERACT WITH
COOLER WATERS DUE TO UPWELLING CAUSED BY THE EXTREMELY SLOW TRACK
SPEEDS. THIS WILL CAUSE 14S TO WEAKEN THROUGH TAU 36, BEFORE IT IS
ABLE TO TRAVERSE BACK OVER WARMER WATERS. NEAR TAU 96, THE SYSTEM
IS FORECAST TO TAP INTO A ROBUST POLEWARD OUTFLOW CHANNEL, ALLOWING
FOR REINTENSIFICATION THROUGH TAU 120. MODELS HAVE BACKED OFF THE
HIGH NORTHWESTERLY SHEAR, AND ARE NOW DEPICTING LESS THAN 15 KTS OF
SHEAR THROUGHOUT THE FORECAST PERIOD. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN MODERATE
AGREEMENT THROUGH TAU 72 WITH THE EXCEPTION OF ONE SIGNIFICANT
OUTLIER IN GALWEM, WHICH ODDLY TRACKS THE VORTEX BACK EASTWARD
THROUGH TAU 36 RATHER THAN SOUTHWARD OR WESTWARD. THE REMAINDER OF
GUIDANCE AGREES ON THE GENERAL TRACK SCENARIO FOR 14S. AFTER TAU
72, MODELS DIVERGE WITH CROSS-TRACK SPREAD INCREASING TO AROUND 300
NM AT TAU 120. ECMWF IS THE SOUTHERNMOST MODEL WHILE UKMET IS THE
NORTHERNMOST. GFS IS ALSO NOTABLY FASTER FROM TAU 72 ONWARD THAN
THE REST OF GUIDANCE, CREATING AN ALONG-TRACK SPREAD OF NEAR 400
NM. OVERALL, THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MODIFIED CONSENSUS (AFTER REMOVING GALWEM) WITH MEDIUM CONFIDENCE
THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER. INTENSITY GUIDANCE
IS IN GENERALLY POOR AGREEMENT, ESPECIALLY AFTER TAU 48. HAFS-A AND
HWRF BOTH SUGGEST A SECOND PEAK AROUND TAU 84-96 OF 110-120 KTS. ON
THE OTHER HAND, GFS AND COAMPS-TC BOTH SUGGESTS A STEADY INTENSITY
OF 60-75 THROUGH TAU 120. THE JTWC INTENSITY FORECAST FOLLOWS
CLOSELY TO HAFS-A THROUGH TAU 48 AND THEN TRIES TO SPLIT THE
DIFFERENCE THROUGH TAU 120, CALLING FOR ONLY MILD
REINTENSIFICATION. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
NNNN