WDXS31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 25S (KARIM) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.7S 93.2E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 1193 NM WEST OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE 25S (KARIM) IS NEARING THE END OF ITS RUN.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS
SIGNIFICANT SHEARING OF THE CONVECTIVE SHIELD AND WARMING OF THE
CLOUD TOPS. THE SYSTEM HAS TRACKED INTO A ZONE OF UNFAVORABLY
COOLER SEA WATERS AND VERTICAL WIND SHEAR VALUES IN EXCESS OF
30KTS. STEERING FLOW PROVIDED BY AN EXTENSION OF THE NEAR
EQUATORIAL RIDGE IS WANING AND THE SYSTEM WILL SOON BE BLOCKED BY
AN ANTICYCLONE TRACKING THROUGH THE SOUTHEAST INDIAN OCEAN. THE
INTENSITY ASSESSMENT SPLITS A RAW ADT VALUE OF T3.2 WITH THE JTWC
DVORAK ASSESSMENT OF 3.0 USING THE SHEAR METHOD. APRF AND DEMS ALSO
WEIGHED IN AT 3.0 DURING THE PREPARATION OF THIS BULLETIN.

INITIAL WIND RADII BASIS: PRESSURE FIELD ANALYSIS AND PERSISTENCE

CURRENT STEERING MECHANISM: THE NEAR EQUATORIAL RIDGE TO THE
NORTHWEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS ADT: 57 KTS AT 101740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30+ KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD

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 FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: MOMENTUM WILL CARRY TROPICAL CYCLONE KARIM
ALONG A SOUTHEASTWARD TRACK FOR ANOTHER TWELVE HOURS UNTIL THE
SYSTEM LOSES ITS STEERING FLOW. IN THE MEANTIME THE CONVECTIVE
SHEILD WILL BE SHREADED BY EXTREMELY HIGH WIND SHEAR AND THE CORE
WILL COLLAPSE DUE TO THE COOLER SEA WATERS. AS TROPICAL CYCLONE KARIM
APPROACHES THE 20TH LATITUDE, A 1036MB SFC HIGH TRACKING TOWARDS
PERTH WILL NUDGE THE REMAINING LOW LEVEL CIRCULATION BACK TOWARDS
THE EQUATORWARD AND THE SYSTEM WILL LOOP AND DIE SOUTH OF THE COCOS
ISLANDS.  

MODEL DISCUSSION: MODEL GUIDANCE HAS BEEN STEADY AND ACCURATE FOR
THE MAJORITY OF THIS STORMS LIFECYCLE. THE DECAY OF THE STORM IS
FORECASTED BASED ON STATISTICAL DYNAMICAL GUIDANCE WHICH OCCURS A
LITTLE MORE RAPIDLY THAN THE DYNAMICAL CONSENSUS.  

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