WDIO31 PGTW 191500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04B (FOUR)
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.7N 88.2E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 55 NM SOUTH-SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 04B IS MAKING LANDFALL ALONG THE COAST OF INDIA, 50NM SOUTH OF
KOLKATA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS
FLARING DEEP CONVECTION AND LIMITED CONVECTIVE BANDING OVER THE
SOUTHERN SEMICIRCLE. EVEN WITH RADAR IMAGERY AND SURFACE
OBSERVATIONS, THE INITIAL POSITION IS DIFFICULT TO LOCATE. THE
INITIAL POSITION IS EXTRAPOLATED FROM A 191026Z SSMIS 91GHZ COLOR
COMPOSITE MICROWAVE IMAGE, WHICH SHOWS SPIRAL BANDING OVER THE
WESTERN SEMICIRCLE WRAPPING INTO THE SOUTHERN QUADRANT OF A RAGGED
BUT DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). SURFACE
OBSERVATIONS SUGGEST THE LLCC IS NEAR SAGAR ISLAND BUT WIND SPEEDS
ARE LESS THAN 15 KNOTS. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE AND IS HEDGED BELOW THE PGTW DVORAK CURRENT
INTENSITY ESTIMATE OF 3.0 BASED ON THE CIMSS ADT ESTIMATE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) POSITIONED TO THE NORTH AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   DEMS: T2.0 - 30 KTS
   CIMSS SATCON: 46 KTS AT 190726Z
   CIMSS ADT: 39 KTS AT 190915Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 04B IS EXPECTED TO TRACK GENERALLY
WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR TO THE
NORTH WHILE RAPIDLY WEAKENING DUE TO THE FRICTIONAL EFFECTS OF
LAND. THE SYSTEM IS EXPECTED TO DISSIPATE BY TAU 12.
 
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT
AGREEMENT WITH A 35 NM (TAU 12) TO 65NM (TAU 24) SPREAD IN
SOLUTIONS LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK.
INTENSITY GUIDANCE SUPPORTS THE RAPID WEAKENING TREND WITH HIGH
CONFIDENCE. 

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