WDIO31 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03B (THREE) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.2N 89.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 267 NM SOUTH OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FAIR
AMOUNT OF CONSOLIDATION IN THE LATE 0500Z HOURS WITH A FLARE-UP OF
DEEP, SYMMETRICAL CONVECTION NEAR THE ASSESSED CENTER BY THE 0600Z
HOUR. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED
ON AN EXTRAPOLATION OF 250417Z ASCAT-C AND 250325Z ASCAT-B PASSES,
AS WELL AS THE PGTW AND DEMS FIX POSITIONS, WHICH LIE IN THE CENTER
OF THE FLARING CONVECTIVE AREA. THE INITIAL INTENSITY IS ASSESSED
AT 35 KNOTS WITH MEDIUM CONFIDENCE. WHILE THE OBJECTIVE ADT AND
SATCON ESTIMATES REMAIN HIGH BETWEEN 45 AND 50 KNOTS, THE AGENCY
SUBJECTIVE ESTIMATES REMAIN IN THE 2.0-2.5 (20-25 KNOT) RANGE AND
THE TWO ASCAT PASSES NOTED ABOVE SHOWED MAXIMUM WINDS IN THE 30-35
KNOT RANGE, PROVIDING SOLID SUPPORT FOR A 35 KNOT INTENSITY. THE
SYSTEM IS MOVING WESTWARD ALONG THE BASE OF AN EXTENSION OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTH. IN THE UPPER-LEVEL, A WEAK
UPPER-LEVEL CYCLONE OVER NORTHEASTERN MYANMAR IS EFFECTIVELY
BLOCKING THE NORMALLY STRONG NORTHEASTERLY FLOW OVER THE BAY OF
BENGAL, LEADING TO LOW (10-15 KNOTS) VWS AND MODERATE WESTWARD
DIVERGENT OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN EXTENSION OF THE DEEP STR TO
THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T2.0 - 30 KTS
   CIMSS SATCON: 46 KTS AT 250323Z
   CIMSS ADT: 49 KTS AT 250315Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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 03B IS FORECAST TO CONTINUE
TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL
RIDGE COMPLEX TO THE NORTH THROUGH THE DURATION OF THE FORECAST. OF
NOTE, THE FORWARD SPEED OF THE PREVIOUS TRACK HAS BEEN REDUCED,
LEADING TO A SHIFT IN THE PROJECTED TIME OF LANDFALL ON THE INDIAN
COAST. THE SYSTEM IS NOW EXPECTED TO MAKE LANDFALL ALONG THE COAST
NORTH OF VISHAKHAPATNAM NEAR TAU 36. THE UPPER-LEVEL ENVIRONMENT IS
FORECAST TO REMAIN MARGINALLY SUPPORTIVE OF INTENSIFICATION THROUGH
TAU 24, WITH LOW TO MODERATE NORTHEASTERLY SHEAR OFFSET BY MODERATE
DIVERGENT OUTFLOW TOWARDS THE WEST. THE SYSTEM IS EXPECTED TO PEAK
AT 45 KNOTS PRIOR TO LANDFALL AND THEN STEADILY WEAKEN AND
ULTIMATELY DISSIPATE OVER LAND NO LATER THAN TAU 72.  

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU
24, THEN DIVERGES STRONGLY THEREAFTER, WITH THE ECMWF AND NAVGEM
DRIVING THE SYSTEM NORTHWESTWARD WHILE THE UKMET AND ENSEMBLE DRIVE
THE SYSTEM SOUTHWEST. THE BULK OF THE GUIDANCE HOWEVER REMAINS
CONSISTENT WITH PREVIOUS RUNS, TAKING THE SYSTEM NEARLY DUE WEST
FOR THE DURATION OF THE FORECAST. WHILE TRACK SPEEDS HAVE BEEN
LOWERED SOMEWHAT, THERE ARE NO SIGNIFICANT CHANGES IN THE FORECAST
TRACK, WHICH CLOSELY FOLLOWS THE GFS SOLUTION WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS MIXED, WITH THE MAJORITY OF THE GUIDANCE
FAVORING INTENSIFICATION THROUGH LANDFALL, WITH THE NOTABLE OUTLIER
OF HWRF. THE JTWC FORECAST LIES ABOVE THE CONSENSUS MEAN THROUGH
LANDFALL WITH MEDIUM CONFIDENCE. 

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