WDXS31 PGTW 231500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN) 
WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.4S 83.8E
   INITIAL INTENSITY: 135 KTS
   GEOGRAPHIC REFERENCE: 740 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 41 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT
TROPICAL CYCLONE 05S (DARIAN) HAS CONTINUED TO INTENSIFY AT A RAPID
PACE DURING THE PAST SIX HOURS. DESPITE INDICATIONS OF AN OPEN
EYEWALL TO THE SOUTHWEST IN A 231133Z SSMIS MICROWAVE IMAGE AND EIR
IMAGERY, THE EYE HAS WARMED TO AROUND +10 DEGREES CELSIUS, AND
AGENCY DVORAK ESTIMATES HAVE RISEN DRAMATICALLY TO T6.5 OR T7.0,
WITH RAW ADT VALUES AS HIGH AS T6.9. THE INITIAL INTENSITY IS THUS
REVISED UPWARD TO 135 KT. THE ENVIRONMENT REMAINS OVERALL FAVORABLE
WITH LOW VERTICAL SHEAR, AND THE CYCLONE APPEARS TO BE MOVING OVER
A PATCH OF WARMER SEA SURFACE TEMPERATURES DURING THE LAST 12
HOURS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   KNES: T7.0 - 140 KTS 
   FMEE: T6.5 - 127 KTS
   CIMSS SATCON: 119 KTS AT 230755Z
   CIMSS ADT: 122 KTS AT 231215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE SHORT-TERM INTENSITY FORECAST HAS
BEEN REVISED UPWARD BY 20-30 KT DURING THE FIRST 24-36 HOURS TO
REFLECT THE RAPID INTENSIFICATION THAT HAS RECENTLY OCCURRED.

FORECAST DISCUSSION: THIS SUPPLEMENTARY WARNING IS PRIMARILY TO
UPDATE THE SHORT-TERM INTENSITY FORECAST DUE TO THE UPWARD REVISION
TO THE INITIAL INTENSITY. INTENSIFICATION COULD CONTINUE BRIEFLY
UNTIL DARIAN BEGINS TO TURN SOUTH OR SOUTH-SOUTHEASTWARD IN 12-24
HOURS DUE TO A DIGGING UPPER-LEVEL TROUGH WEST OF AUSTRALIA AND A 
STRENGTHENING WESTERLY WIND BURST SOUTH OF THE EQUATOR. DURING THIS 
TURN, THE CYCLONE'S FORWARD MOTION WILL SLOW. THE RESULTING INCREASE 
IN OCEANIC UPWELLING WILL LIKELY INDUCE WEAKENING ONCE MORE, WHICH 
HAS BEEN CONSISTENTLY FORECAST BY THE COUPLED HWRF AND COAMPS-TC 
MODELS. A PERIOD OF RAPID WEAKENING IS EXPECTED DURING THE 24-48 HOUR 
PERIOD WHEN UPWELLING IS FORECAST TO BE MAXIMIZED. WEAKENING SHOULD 
BE MORE GRADUAL THEREAFTER AS THE CYCLONE EVENTUALLY MOVES SOUTH AND
SOUTHWESTWARD OVER SUBTROPICAL WATERS COOLER THAN 26 DEGREES CELSIUS.

MODEL DISCUSSION: THE JTWC TRACK FORECAST IS CLOSE TO THE
MULTI-MODEL CONSENSUS, SLIGHTLY EAST OF THE PREVIOUS FORECAST
THROUGH THE FIRST 72 HOURS. THE JTWC INTENSITY FORECAST IS A LITTLE
ABOVE THE MULTI-MODEL CONSENSUS DUE TO THE POOR REPRESENTATION OF
THE INITIAL INTENSITY IN SOME MODELS, BUT REMAINS INSIDE THE UPPER
RANGE OF THE GUIDANCE.

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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