WDIO31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (SHAKHTI) WARNING 
NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.3N 63.4E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 264 NM EAST-NORTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
WELL-DEFINED, COMPACT LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTION CONFINED TO THE SOUTHERN PERIPHERY. TROPICAL CYCLONE
(TC) 02A HAS STRUGGLED TO FORM AN EYE OVER THE PAST 6 HOURS,
HOWEVER, A RAGGED EYE HAS OCCASIONALLY PEEKED OUT FROM UNDER THE
CENTRAL DENSE OVERCAST. A 041348Z 37GHZ MICROWAVE IMAGE
REVEALS A SYMMETRICAL MICROWAVE EYE, INDICATIVE OF INTENSIFICATION
SINCE THE PREVIOUS FORECAST. ENVIRONMENTAL ANALYSIS INDICATES AN 
OVERALL FAVORABLE ENVIRONMENT, CHARACTERIZED BY WARM (28-29C) SEA 
SURFACE TEMPERATURES, LOW TO MODERATE (15-20 KTS) VERTICAL WIND 
SHEAR, AND MODERATE OUTFLOW ALOFT, OFFSET BY MINOR MID-LEVEL DRY AIR 
ENTRAINMENT FROM THE SOUTH. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE AFOREMENTIONED 37GHZ MICROWAVE IMAGE.
THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE AGENCY DVORAK FIXES AND OBJECTIVE INTENSITY AIDS
LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHEASTERN PERIPHERY OF A STRONG
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHWEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 70 KTS AT 040922Z
   CIMSS ADT: 74 KTS AT 041200Z
   CIMSS AIDT: 67 KTS AT 041100Z
   CIMSS D-MINT: 64 KTS AT 041144Z
   CIMSS D-PRINT: 64 KTS AT 041200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: MID-LEVEL DRY AIR

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 02A IS FORECAST TO CONTINUE ITS
WEST-SOUTHWESTWARD TRACK THROUGH TAU 24 AS 02A IS INFLUENCED BY THE
SOUTHEASTERN PERIPHERY OF THE PRIMARY STEERING RIDGE. BETWEEN TAUS
12-36, THE WEAKER STR POSITIONED OVER SOUTHERN INDIA AND THE
ARABIAN SEA WILL BUILD AND EXTEND SOUTHWEST AND WEST, CAUSING 02A
TO STALL IN THE INCREASINGLY COMPETITIVE STEERING ENVIRONMENT. 02A
WILL BEGIN A RECURVE AROUND TAU 24, HOWEVER, MODELS ARE IN
SIGNIFICANT DISAGREEMENT OVER WHERE THE TURN WILL OCCUR. AFTER TAU
24, 02A IS EXPECTED TO ENTER UNDER THE STEERING INFLUENCE OF THE
NOW DOMINANT STR TO ITS SOUTH AND TRACK EAST-SOUTHEASTWARD UNTIL
DISSIPATION AROUND TAU 72. REGARDING INTENSITY, 02A IS EXPECTED TO
MAINTAIN ITS INTENSITY OF 65 KTS FOR THE NEXT 24 HOURS, BEFORE
BEGINNING A CONSISTENT WEAKENING TREND THAT WILL LEAD TO
DISSIPATION NO LATER THAN TAU 72. TC 02A IS FORECAST TO EXPERIENCE 
RAPID DETERIORATION DUE TO INCREASING VERTICAL WIND SHEAR AND
SIGNIFICANT DRY AIR ENTRAINMENT THROUGHOUT ALL LEVELS.

MODEL DISCUSSION: DETERMINISTIC MODELS ARE IN GOOD AGREEMENT
THROUGH TAU 24. ALL MODELS PREDICT A SOUTHWESTWARD TRACK BUT HAVE
LARGE DIFFERENCES IN THE TRACK SPEED THAT IMPACT WHERE 02A WILL
RECURVE. THE MAJORITY OF MODELS SHOW THE RECURVE BEGINNING AT TAU
36; HOWEVER, THE LOCATION OF TAU 36 VARIES GREATLY AMONGST MEMBERS.
NAVGEM REMAINS THE LARGEST OUTLIER IN JTWC CONSENSUS, HOLDING 02A
ON A STRAIGHT SOUTHWESTWARD TRACK UNTIL TAU 60. THE GFS ENSEMBLE
MEAN AND DETERMINISTIC GFS TRACKS FALL IN THE OTHER EXTREME, BOTH
FORECASTING 02A TO MAKE A HAIRPIN RECURVE AT TAU 36 BEFORE TRACKING
DUE EAST. THE JTWC TRACK FORECAST IS MOST SIMILAR TO THE ECMWF
DETERMINISTIC, ECMWF ENSEMBLES, AND GALWEM, SLIGHTLY TO THE EAST OF
THE MULTI-MODEL CONSENSUS MEAN. AS A RESULT OF THE POOR MODEL
AGREEMENT, THE JTWC TRACK FORECAST PLACED WITH OVERALL LOW
CONFIDENCE. CONVERSELY, RELIABLE INTENSITY GUIDANCE IS IN GOOD
AGREEMENT THROUGHOUT THE FORECAST PERIOD. THERE ARE MINOR
DIFFERENCES ON WHETHER 02A WILL CONTINUE TO INTENSIFY OR BEGIN ITS
WEAKENING TREND, OPENING UP THE POSSIBILITY OF A PEAK INTENSITY
HIGHER THAN 65 KTS. AS A RESULT, THE JTWC INTENSITY FORECAST IS
PLACED WITH OVERALL MEDIUM CONFIDENCE.

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