WDIO32 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05B (DITWAH) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.1N 81.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 966 NM SOUTH-SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION, AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 05B (DITWAH) AS IT TRANSITS NORTHWARD TO NORTHWESTWARD 
ALONG THE INTERIOR SECTION OF THE EASTERN COAST OF SRI LANKA. THE 
CIRCULATION REMAINS BROAD, WITH SPIRAL BANDS OF DEEP CONVECTION 
WRAPPING INTO THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE WIND FIELD 
IS STILL EXTENDING WELL BEYOND THE PERIMETER OF SRI LANKA. THE INITIAL
POSITION IS ASSESSED WITH HIGH CONFIDENCE UTILIZING ANIMATED
SHORTWAVE INFRARED SATELLITE IMAGERY LOOP. THE INITIAL INTENSITY OF
35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON PERSISTENCE OF THE 
CONVECTIVE STRUCTURE AND SURFACE OBSERVATIONS. ENVIRONMENTAL ANALYSIS 
REVEALS MARGINAL THERMODYNAMIC CONDITIONS, WITH MODERATE DUAL CHANNEL 
OUTFLOW, LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS) OFFSET 
BY FRICTIONAL EFFECTS OF LANDFALL INTERACTION.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW-LEVEL RIDGING TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   CIMSS D-MINT: 36 KTS AT 280033Z
   CIMSS D-PRINT: 41 KTS AT 280100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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 DITWAH IS FORECAST TO CONTINUE TRACKING
POLEWARD UNDER THE INFLUENCE OF A LOW-LEVEL SUBTROPICAL RIDGING
CENTERED TO THE EAST. THE LLCC IS EXPECTED TO REMAIN OVER LAND
UNTIL TAU 24, WHILE SUSTAINING INTENSITY ALONG THE TRANSIT. AFTER
THAT, POSITIVE IMPACTS OF WARM (28-29 C) SEA SURFACE TEMPERATURES
(SST) AND REDUCED FRICTIONAL EFFECTS WILL BE OFFSET BY INCREASING
SOUTHERLY VWS, ULTIMATELY RESULTING IN A WEAKENING TREND AND
DISSIPATION OVER WATER BETWEEN TAUS 36 AND 48. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT IN REGARD TO THE POLEWARD TRACK. THE CROSS-TRACK GUIDANCE
DISPERSION AT TAU 12 IS 65 NM AND EXPANDS TO 90 NM BY THE END OF THE
FORECAST PERIOD. INTENSITY GUIDANCE IS IN FAIR AGREEMENT, WITH
MAJORITY OF THE MODELS INDICATING A WEAKENING TREND WITH TIME AND
DISSIPATION WITHIN 24-48 HOURS. THE MAJOR OUTLIER REMAINS NAVGEM
DRIVEN COAMPS-TC WHICH DEPICTS A STRENGTHENING TO A PEAK OF 55 KTS,
WHILE THE SYSTEM IS OVER WATER. AS SUCH, JTWC OFFICIAL INTENSITY
FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE.

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