WDIO31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02B (ASANI) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.7N 88.6E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 654 NM SOUTH OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS INTENSE
BURSTS OF DEEP CONVECTION, VORTICAL HOT TOWERS, FLARING WITHIN AN
IRREGULAR CENTRAL DENSE OVERCAST (CDO) WITH CLOUD TOP TEMPERATURES
OBSERVED AS COLD AS -94.0C. A 080408Z METOP-B MHS 89GHZ MICROWAVE
IMAGE REVEALS TIGHTLY-CURVED BANDING WRAPPING INTO THE EASTERN
QUADRANT OF THE LOW-LEVEL CIRCULATION CENTER (LLCC) WITH INTENSE
DEEP CONVECTION ALONG THE SOUTHEASTERN QUADRANT. THE COINCIDENT
080411Z ASCAT-B IMAGE SHOWS 60-65 KNOT WINDS WITHIN THIS INTENSE
CONVECTIVE BAND. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON A 080409Z ASCAT-B AMBIGUITY PRODUCT, WHICH
SHOWS A WELL-DEFINED CENTER. DESPITE INCREASING EASTERLY VERTICAL
WIND SHEAR (VWS), POLEWARD AND WESTWARD OUTFLOW REMAIN VIGOROUS
ALLOWING THE SYSTEM TO MAINTAIN A COMPACT CDO AND VORTICAL HOT
TOWERS. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE PGTW DVORAK ESTIMATE, ASCAT-B DATA AND UW-
CIMSS SATCON AND ADT ESTIMATES.

INITIAL WIND RADII BASIS: DETAILED ANALYSIS OF RECENT SCATTEROMETER
DATA 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) ENTRENCHED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS SATCON: 63 KTS AT 080151Z
   CIMSS ADT: 65 KTS AT 080315Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 31-32 CELSIUS
   OUTFLOW: STRONG WESTWARD

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 02B IS EXPECTED TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE PERIPHERY OF THE STR THROUGH TAU 48. DUE TO
THE COMPACT CORE AND ROBUST OUTFLOW THROUGH TAU 24, TC 02B WILL
INTENSIFY SLIGHTLY TO 75 KNOTS AT TAU 12 TO TAU 24. AFTER TAU 24,
THE SYSTEM WILL STEADILY WEAKEN AS EASTERLY VWS INCREASES TO 30-35
KNOTS AND OUTFLOW DECREASES. AFTER TAU 48, INCREASING WESTERLIES
OVER NORTHEAST INDIA WILL GRADUALLY ERODE THE STR ALLOWING THE
SYSTEM TO TURN POLEWARD. AFTER TAU 72, TC 02B WILL TRACK
NORTHEASTWARD AND WILL INTERACT WITH THE MIDLATITUDE TROUGH
EXPECTED TO DEEPEN OVER THE NORTHERN BAY OF BENGAL WITH SIGNIFICANT
WEAKENING DOWN TO 35 KNOTS BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48 BUT DIVERGES QUICKLY THROUGH THE REMAINDER OF THE
FORECAST PERIOD. ALTHOUGH NAVGEM REMAINS THE WESTERN MOST OUTLIER,
IT NOW INDICATES A SHARP RECURVE NORTH-NORTHEASTWARD ALONG THE
EASTERN COAST OF INDIA. THE BULK OF THE NUMERICAL GUIDANCE
INDICATES A TRACK TOWARD KOLKATA, INDIA AND BANGLADESH WITH AFUM 
TRACKING THE SYSTEM INTO NORTHEAST INDIA AND GFS TRACKING THE
SYSTEM INTO MYANMAR. THE 080000Z ECMWF ENSEMBLE (EPS) STRIKE
PROBABILITY PRODUCT CONTINUES TO SHOW A HIGH PROBABILITY OF THE
SYSTEM TRACKING ALONG OR JUST EAST OF THE NORTHEAST COAST OF
INDIA. THERE ARE ALSO SIGNIFICANT DIFFERENCES IN ALONG TRACK SPEED
AFTER TAU 72 SO LOW CONFIDENCE IN THE JTWC TRACK FORECAST IN THE
EXTENDED PERIOD. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE JTWC
INTENSITY FORECAST WITH A SHORT WINDOW FOR SLIGHT INTENSIFICATION 
OVER THE NEXT DAY. TC 02B COULD WEAKEN MORE RAPIDLY IF IT TRACKS 
CLOSER TO LAND.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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