WDIO31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02B (ASANI) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.4N 81.2E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 594 NM SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) AND WATER VAPOR SATELLITE IMAGERY
SHOWS THE CONVECTIVE SHIELD RUNNING AHEAD OF THE LOW LEVEL
CIRCULATION CENTER AS INCREASING EASTERLY WIND SHEAR IS AFFECTING
THE SYSTEM. A 101616Z ASCAT PASS REVEALED THE LOW LEVEL CIRCULATION
CENTER (LLCC) AND CONFIRMED THAT THE CONVECTIVE SHIELD WAS A GOOD
DEAL WESTWARD OF THE LLCC. THE SCATTEROMETRY ALSO REVEALED VIGOROUS
OFF-SHORE FLOW OVER THE GUDIVA AND MACHILIPATNAM REGION. THE
INTENSITY ASSESSMENT IS 5-10KTS HIGHER THAN THAT CONFIRMED BY THE
SCATTEROMETRY DUE TO THE EXPECTED TREND AND A RAW ADT VALUE OF T3.7
ALONG WITH A SATCON ASSESSMENT OF 58KTS. TROPICAL CYCLONE ASANI HAS
ACCELERATED ITS WESTWARD TRAJECTORY OVER THE PAST SIX HOURS AND
TAKEN A MORE WESTERLY COURSE TOWARDS THE COAST.  STORM MOVEMENT IS
MITIGATING THE EFFECTS OF EASTERLY SHEAR TO SOME EXTENT WHILE
OTHERWISE THE ENVIRONMENT REMAINS FAVORABLE, ALTHOUGH THE OFF-SHORE
FLOW IS DECREASING SATURATION OVER THE POLEWARD SEMICIRCLE.

INITIAL WIND RADII BASIS: 101616Z ASCAT 25KM

CURRENT STEERING MECHANISM: MOMENTUM, AS THE SYSTEM HAS TRACKED
AWAY FROM THE INFLUENCE OF THE WARM RIDGE EXTENDING OVER THE MALAY
PENINSULA TOWARDS BANGLEDESH. THE SYSTEM IS ENTERING AN AREA OF
UPPER LEVEL TROUGHING AND WILL SOON BEGINNING CURLING AROUND TO THE
NORTHEAST.  

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS SATCON: 58 KTS AT 101614Z
   CIMSS ADT: 67 KTS AT 101815Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: FORTY HOURS OVER LAND WILL SUBSTANTIALLY WEAKEN
THE SYSTEM BEFORE IT RETURNS TO SEA.

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE ASANI HAS ANOTHER TWELVE
HOURS OF OVER WATER TRACK IN A REASONABLY FAVORABLE ENVIRONMENT
BEFORE IT MAKES LANDFALL NEAR FALSE DIVI POINT. SIMULTANEOUS WITH
THE LANDFALL THE COMPLETE LOSS OF STEERING FORCE AND MOMENTUM WILL
ALLOW THE STORM TO CURL AROUND TO THE NORTHEAST AND TRACK SEAWARD.
THE EXPECTED EGRESS REGION IS THE PODICHERRY REGION. HOW MUCH OF THE
STORM REMAINS AS IT RETURNS TO SEA AND HOW SUCCESSFUL IT IS IN
REGENERATING IS HIGHLY UNCERTAIN AT THIS POINT. 

MODEL DISCUSSION: THE BULK OF MODEL GUIDANCE CONTINUES TO SUPPORT A
ROLLOVER TO THE NORTHEAST AND RETURN TO SEA AT WELL BELOW TROPICAL
STORM STRENGTH. MOST OF THE TRACKERS LOSE THE VORTEX BY TAU 72. THE
JTWC TRACK FORECAST STAYS CLOSE TO THE ECMWF AND GFS ENSEMBLE MEANS
WHILE THERE IS ABOVE AVERAGE AGREEMENT ON INTENSITY INCLUDING GOOD
AGREEMENT BETWEEN STATISTICAL DYNAMIC AND DYNAMIC GUIDANCE. AS A
RESULT THE JTWC INTENSITY FORECAST STAYS ON THE MEAN. 

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