WDIO31 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07B (MIDHILI) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.5N 89.9E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 106 NM SOUTHEAST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A NOW FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) JUST SOUTH OF THE
COASTLINE OF BANGLADESH. OVER THE PAST SIX HOURS, THE DEEP
CONVECTION WHICH HAD DEVELOPED INTO A CENTRAL DENSE OVERCAST (CDO)
CENTERED OVER THE LLCC, HAS BEEN RAPIDLY TORN ASUNDER BY THE STRONG
SOUTHWESTERLY SHEAR, LEAVING BEHIND A NAKED CIRCULATION. HOWEVER,
BASED ON A 170318Z ASCAT-B PASS, THE LOW-LEVEL WIND FIELD HAS
STEADILY INTENSIFIED, THOUGH THE AREAL EXTENT REMAINS VERY SMALL.
THE SCATTEROMETER PASS REVEALED WINDS OF UP TO 40 KNOTS ALONG THE
WESTERN PERIPHERY OF THE CIRCULATION AND UP TO 37 KNOTS IN THE
EASTERN PORTION. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE EXPOSED LLCC IN MULTIPLE SATELLITE PASSES
INCLUDING HIMAWARI-9, METEOSAT-9 AND EWS-G2. THE INITIAL INTENSITY
IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE SCATTEROMETER DATA
DISCUSSED ABOVE. THE SYSTEM IS TRACKING QUICKLY TO THE NORTHEAST
ALONG THE WESTERN SIDE OF THE SUBTROPICAL RIDGE (STR), THROUGH AN
UNFAVORABLE ENVIRONMENT CHARACTERIZED BY WARM SSTS, AND ROBUST
POLEWARD OUTFLOW OFFSET BY STRONG SOUTHWESTERLY SHEAR AND MID-LEVEL
DRY AIR MOVING IN FROM THE WEST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 35 KTS AT 170300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30+ KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY MID-LEVEL AIR ENGULFING THE SYSTEM FROM THE
WEST. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 07B (MIDHILI) WILL CONTINUE TO TRACK
TOWARDS THE NORTHEAST THROUGH THE FORECAST PERIOD, MAKING LANDFALL
ALONG THE COAST OF CENTRAL BANGLADESH WITHIN THE NEXT COUPLE OF
HOURS. DUE TO THE RECENT SHEARING APART OF THE VORTEX, NO
ADDITIONAL INTENSIFICATION IS EXPECTED PRIOR TO LANDFALL. ONCE
ASHORE, FRICTIONAL EFFECTS WILL RAPIDLY WEAKEN THE REMNANT
LOW-LEVEL VORTEX, WHICH IS FORECAST TO FULLY DISSIPATE WITHIN THE
NEXT 24 HOURS WHILE INTO FAR EASTERN PORTIONS OF INDIA. 

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT THAT THE SYSTEM WILL TRACK NORTHEAST THROUGH THE DURATION
OF THE SHORT FORECAST PERIOD. INTENSITY GUIDANCE IS ALSO IN VERY
GOOD AGREEMENT IN SHOWING THE SYSTEM RAPIDLY WEAKENING AND ULTIMATELY
DISSIPATING OVER THE EASTERN PROVINCES OF INDIA WITHIN THE NEXT 24
HOURS. 

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