WDIO31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02B (TWO) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.1N 90.5E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 760 NM SOUTH OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 15 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 -98.7C. A 071249Z SSMIS 91GHZ MICROWAVE IMAGE
INDICATES A CONSOLIDATING SYSTEM WITH SPIRAL BANDING OVER THE
WESTERN SEMICIRCLE WRAPPING INTO THE COMPACT CORE, WHICH IS
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). OVERALL, THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A SERIES
OF HIGH-RESOLUTION MICROWAVE IMAGES. DESPITE SOME PRESSURE OVER THE
EASTERN SEMICIRCLE DUE TO EASTERLY VERTICAL WIND SHEAR (VWS),
POLEWARD AND WESTWARD OUTFLOW REMAINS VIGOROUS ALLOWING THE SYSTEM
TO MAINTAIN THE SMALL CDO. ADDITIONALLY, THE SYSTEM IS FIGHTING THE 
EASTERLY VWS WITH IMPROVING OUTFLOW OVER THE EASTERN SEMICIRCLE OVER 
THE PAST TWO HOURS. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH 
MEDIUM CONFIDENCE BASED ON A PGTW DATA-T ESTIMATE OF 3.0 (45 KNOTS) 
AS WELL AS RECENT ADT AND AIDT ESTIMATES RANGING FROM 40-51 KNOTS. 
THE PGTW FINAL-T ESTIMATE IS SLIGHTLY LOWER AT T2.5 DUE TO 
CONSTRAINTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTHEAST AND EAST 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T1.5 - 25 KTS
   CIMSS ADT: 51 KTS AT 071215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 31-32 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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 02B IS EXPECTED TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE PERIPHERY OF THE STR THROUGH TAU 48. DUE TO
THE COMPACT CORE AND GENERALLY FAVORABLE CONDITIONS, TC 02B WILL
INTENSIFY AT A CLIMATOLOGICAL RATE THROUGH TAU 36 REACHING A PEAK
INTENSITY OF 75 KNOTS. AFTER TAU 48, THE STR IS FORECAST TO REALIGN
IN RESPONSE TO AN APPROACHING MIDLATITUDE SHORTWAVE TROUGH, WHICH
WILL DEEPEN OVER EASTERN INDIA, ALLOWING THE SYSTEM TO TURN
POLEWARD. GRADUAL WEAKENING IS ANTICIPATED AS UPPER-LEVEL EASTERLY
FLOW INCREASES AND POLEWARD OUTFLOW WEAKENS. AFTER TAU 72, THE
SYSTEM WILL RECURVE NORTH-NORTHEASTWARD AND WEAKEN STEADILY AS IT
ENCOUNTERS MIDLATITUDE WESTERLIES AND ENTRAINS DRY AIR. 

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, WHICH TRACKS THE
SYSTEM WESTWARD INTO EAST CENTRAL INDIA, NUMERICAL MODEL GUIDANCE
IS IN FAIR AGREEMENT SUPPORTING THE RECURVE SCENARIO THUS OVERALL
CONFIDENCE IS MEDIUM THROUGH THE FORECAST PERIOD. THE 070600Z ECMWF
ENSEMBLE (EPS) RUN INDICATES UNCERTAINTY IN THE EXACT TRACK AS THE
SYSTEM RECURVES WITH A DISTINCT POSSIBILITY OF A TRACK ALONG OR
JUST EAST OF THE NORTHEAST COAST OF INDIA, WHICH WILL OBVIOUSLY
LEAD TO MORE RAPID WEAKENING. THE PRESENCE OF VORTICAL HOT TOWERS
AND THE PERSISTENT, EXPANDING CDO SUPPORT THE CONTINUED 
INTENSIFICATION TREND THUS THE JTWC INTENSITY FORECAST IS PLACED
HIGHER THAN HWRF AND THE INTENSITY CONSENSUS (ICNW) WHICH PEAK THE
SYSTEM AT 55-60 KNOTS. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE
JTWC INTENSITY FORECAST.

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