WDIO32 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05B (DITWAH)     
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.3N 81.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 958 NM SOUTH-SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 05B CONTINUES TO TRACK SLOWLY POLEWARD OVER THE 
NORTHEASTERN REGION OF SRI LANKA. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) DEPICTS A BROAD, RAGGED LOW-LEVEL CIRCULATION CENTER 
(LLCC), WITH SPIRAL BANDING DISPLACED TO THE NORTH AND WEST OVER 
WATER. A 280150Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS EXTENSIVE 
FRAGMENTED BANDING, WITH NO ORGANIZED OR DEFINED LLCC EVIDENT. LIMITED 
SURFACE OBSERVATIONS SHOW THE BROAD CIRCULATION BUT ARE SUSTAINED AT 
LESS THAN 10 KNOTS REFLECTING THE WEAK NATURE OF THE LLCC. ALTHOUGH 
ROBUST POLEWARD OUTFLOW CONTINUES TO SUPPORT THE OUTER BANDING, 
FRICTIONAL EFFECTS AND DRY AIR ENTRAINMENT CONTINUE TO SERIOUSLY 
HINDER CORE DEVELOPMENT. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON THE MSI. THE INITIAL INTENSITY OF 35 KTS IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE OVERALL WEAK STRUCTURE 
AND VERY LIMITED CIMSS INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: LOW-LEVEL SUBTROPICAL RIDGE POSITIONED
TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   CIMSS D-MINT: 37 KTS AT 280151Z
   CIMSS D-PRINT: 39 KTS AT 280600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT, FRICTIONAL EFFECTS

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: TC 05B WILL TRACK NORTHWARD THROUGH THE FORECAST 
PERIOD SKIRTING THE SOUTHEASTERN COAST OF INDIA. THE SYSTEM WILL 
MAINTAIN INTENSITY DUE TO PERSISTENT FRICTIONAL EFFECTS AND DRY AIR 
ENTRAINMENT THROUGH TAU 36, WITH DISSIPATION ANTICIPATED BY TAU 48 
WHEN THE SYSTEM TRACKS UNDER INCREASING SOUTHERLY FLOW ALOFT WITH 
INCREASING VERTICAL WIND SHEAR.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT 
SUPPORTING THE JTWC TRACK FORECAST WITH MEDIUM CONFIDENCE. THE 280000Z 
GEFS AND EPS RUNS ARE ALSO IN FAIR AGREEMENT, WITH THE BULK OF THE 
SOLUTIONS OVER WATER. THE BULK OF THE RELIABLE INTENSITY GUIDANCE 
INDICATES STEADY WEAKENING THROUGHTAU 48. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM//
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