WDIO31 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (TWO) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.5N 67.2E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 198 NM SOUTH OF KARACHI, PAKISTAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION FLARING AND CONSOLIDATING OVER A LOW-LEVEL CIRCULATION
CENTER EVIDENT IN 022110Z AMSR2 IMAGERY. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE AMSR2 DATA. THE INITIAL 
INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 
CONSENSUS OF AVAILABLE AGENCY SUBJECTIVE DVORAK VALUES, AUTOMATED 
ESTIMATES, AND DERIVED WIND SPEED DATA ASSOCIATED WITH THE 022110Z 
AMSR2 PASS. 02A HAS CONSOLIDATED INTO A TROPICAL CYCLONE OVER THE 
PAST SIX HOURS UNDER THE INFLUENCE OF A SUPPORTIVE UPPER-LEVEL 
CONDITIONS AND PASSAGE OVER WARM WATER.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND 012108Z AMSR2
DERIVED WIND SPEED DATA

CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE EXTENSION
TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T2.0 - 30 KTS
   CIMSS ADT: 35 KTS AT 030130Z
   CIMSS AIDT: 35 KTS AT 030130Z
   CIMSS D-MINT: 40 KTS AT 030123Z
   CIMSS D-PRINT: 42 KTS AT 030130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE DUAL-CHANNEL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: 02A IS EXPECTED TO TRACK GENERALLY WESTWARD TO
WEST-SOUTHWESTWARD OVER THE NEXT 48 HOURS UNDER THE CONTINUED
INFLUENCE OF SUBTROPICAL RIDGING TO THE NORTH. THEREAFTER, A DEEP
SHORTWAVE TROUGH DEVELOPING TO THE NORTH WILL DIG EQUATORWARD AND
ERODE THE STEERING RIDGE, SHIFTING THE PRIMARY STEERING MECHANISM
TO RIDGING SITUATED TO THE SOUTH AND EAST OF THE SYSTEM. THE CHANGE
IN PRIMARY STEERING MECHANISMS WILL REVERSE THE STORM MOTION TO
EAST-NORTHEASTWARD AND CARRY THE SYSTEM TOWARD POTENTIAL LANDFALL 
ALONG THE INDIAN WEST COAST IN THE EXTENDED PERIOD. THE DIGGING 
SHORTWAVE TROUGH IS ALSO EXPECTED TO DIRECTLY IMPACT THE SYSTEM BY 
TAU 48, INTRODUCING INCREASING VERTICAL WIND SHEAR AND ALLOWING THE 
SYSTEM TO ENTRAIN DRIER AIR FROM THE SURROUNDING ENVIRONMENT. THESE 
NEGATIVE INFLUENCES WILL LEAD TO STEADY WEAKENING, WITH DISSIPATION 
BELOW THE WARNING THRESHOLD INTENSITY OF 35 KNOTS ANTICIPATED PRIOR 
TO LANDFALL.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT REGARDING
THE OVERALL FORECAST SCENARIO IN TERMS OF BOTH TRACK AND INTENSITY.
NEARLY ALL GUIDANCE DEPICTS GENERALLY WESTWARD TO
WEST-SOUTHWESTWARD MOTION THROUGH THE NEXT 48 TO 72 HOURS, FOLLOWED
BY A TURN BACK TO THE EAST AS THE STEERING MECHANISM SHIFTS.
HOWEVER, THERE IS NOTABLE SPREAD IN THE SPEED AND EXTENT OF
WESTWARD MOTION AND THE TIGHTNESS OF THE TURN BACK TO THE EAST. GFS
AND UKMET-BASED SOLUTIONS LIE CLOSE TO THE CURRENT FORECAST TRACK
WHILE THE ECMWF DETERMINISTIC AND ENSEMBLE MEAN SOLUTIONS DEPICT A
TRACK FARTHER TO THE WEST FOLLOWED BY A BROADER TURN AND LIKELY
DISSIPATION OVER WATER BEFORE THE SYSTEM CAN MAKE LANDFALL IN
INDIA. ENSEMBLE MODEL MEMBERS SPAN THE GAP BETWEEN THESE TWO
GROUPINGS. THERE IS MORE AGREEMENT AMONG NUMERICAL MODEL INTENSITY
GUIDANCE, ALL OF WHICH DEPICTS THE SYSTEM TAKING ADVANTAGE OF LOW
VERTICAL WINDS SHEAR AND FAVORABLE UPPER-LEVEL OUTFLOW TO INTENSIFY
STEADILY TO RAPIDLY IN THE NEAR-TERM AND DISSIPATING QUICKLY IN
HOSTILE CONDITIONS AFTER TAU 48. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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