WDXS32 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (GARANCE) WARNING 
NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.1S 54.9E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 217 NM SOUTH OF ST DENIS, LA REUNION
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS BEGUN TO ERODE AS CONVECTIVE TOPS WARMED AND THE COLD DENSE
OVERCAST UNRAVELED, MOSTLY EXPOSING THE LOW-LEVEL CIRCULATION
(LLC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
THE EXPOSED LLC. THE INITIAL INTENSITY IS ALSO PLACED WITH HIGH
CONFIDENCE BASED ON AGENCY DVORAK ESTIMATES AND REFLECTS THE
WEAKENING. ANALYSIS INDICATES THE ENVIRONMENT HAS BECOME
UNFAVORABLE AS VWS HAS SIGNIFICANTLY INCREASED, OFFSETTING THE WARM
SST AND MODERATE OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA. 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T3.5 - 55 KTS
   FIMP: T4.0 - 65 KTS
   CIMSS SATCON: 57 KTS AT 281438Z
   CIMSS ADT: 67 KTS AT 281800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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 GARANCE WILL CONTINUE TO TRACK SOUTHWARD
UNDER THE STR TO THE EAST. THE UNFAVORABLE ENVIRONMENT, IN ADDITION
TO COOLING SST, WILL GRADUALLY ERODE THE SYSTEM DOWN TO 45 KTS BY
TAU 24. CONCURRENTLY BY TAU 24, THE TC WILL START EXTRA-TROPICAL
TRANSITION AS IT ENTERS THE BAROCLINIC ZONE, BECOMING A COLD CORE
LOW WITH GALE-FORCE WINDS BY TAU 36.  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH AN
EVEN AND GRADUAL SPREAD TO 164NM BY TAU 36, LENDING HIGH CONFIDENCE
IN THE JTWC TRACK FORECAST. THERE IS ONLY MEDIUM CONFIDENCE IN THE
INTENSITY FORECAST DUE TO UNCERTAINTIES ASSOCIATED WITH
EXTRA-TROPICAL TRANSITION. 

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