WDIO31 PGTW 050900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (SHAKHTI) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.5N 61.4E INITIAL INTENSITY: 65 KTS GEOGRAPHIC REFERENCE: 146 NM EAST OF MASIRAH ISLAND MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT DEEP CONVECTION OFFSET TO THE SOUTH OF THE COMPACT LOW-LEVEL CIRCULATION CENTER (LLCC). THE POLEWARD OUTFLOW HAS WEAKENED, INDICATIVE OF THE EASTERLY DRY AIR ENTRAINMENT AND THE EAST- NORTHEASTERLY SHEAR. A 050216Z WSFM MICROWAVE IMAGE REVEALS THAT TROPICAL CYCLONE (TC) 02A HAS RETAINED ITS MICROWAVE EYE, DESPITE THE MARGINALLY UNFAVORABLE ENVIRONMENT AND OBFUSCATION OF THE LLCC BY THE CENTRAL DENSE OVERCAST. ANALYSIS INDICATES THAT THE ENVIRONMENT IS CHARACTERIZED BY MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR, DRY AIR, AND UPWELLING ASSOCIATED WITH THE STORM'S STAGNATION. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON EXTRAPOLATION FROM THE AFOREMENTIONED 050216Z WSFM MICROWAVE IMAGE AND A 050436Z METOP-B ASCAT PARTIAL PASS REVEALING THE LLCC. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE 050436Z METOP-B ASCAT PARTIAL PASS, CORROBORATED BY THE OBJECTIVE INTENSITY AIDS AND AGENCY DVORAK FIXES LISTED BELOW. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND THE 050436Z METOP- B ASCAT IMAGE. CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT BETWEEN A SUBTROPICAL RIDGE (STR) POSITIONED OVER SAUDI ARABIA AND AN STR POSITIONED OVER THE EASTERN ARABIAN SEA AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS KNES: T4.5 - 77 KTS DEMS: T3.5 - 55 KTS CIMSS ADT: 57 KTS AT 050630Z CIMSS AIDT: 68 KTS AT 050630Z CIMSS D-PRINT: 57 KTS AT 050630Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 20-25 KTS SST: 27-28 CELSIUS OUTFLOW: MODERATE EQUATORWARD OTHER FACTORS: DRY AIR ENTRAINMENT AND UPWELLING ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 02A WILL CONTINUE ITS SLOW SOUTHWESTWARD TRACK FOR THE NEXT 24 HOURS AS IT REMAINS UNDER THE INFLUENCE OF THE SOUTHEASTERN PERIPHERY OF THE PRIMARY STEERING RIDGE OVER SAUDI ARABIA. AROUND TAU 24, 02A WILL TAKE AN EAST-SOUTHEASTWARD CURVE AS A DEEP-LAYER TROUGH BREAKS DOWN THE STR POSITIONED OVER THE EASTERN ARABIAN SEA. THE STR WILL EXTEND SOUTHWEST AND WEST, CAUSING 02A TO BRIEFLY STALL BEFORE RECURVING OVER THE NOW-DOMINANT STEERING RIDGE. 02A WILL TRACK EAST-SOUTHEASTWARD ALONG THE NORTHWESTERN PERIPHERY OF THE STR UNTIL THE END OF THE FORECAST PERIOD. 02A IS FORECAST TO STEADILY WEAKEN FROM HERE ON OUT DUE TO THE SIGNIFICANT DRY AIR ENTRAINMENT AND INCREASING WIND SHEAR. AS A RESULT OF THE STORM'S SLOW TRACK MOTION, COOLER WATER UPWELLING HAS ALSO HINDERED DEVELOPMENT AND WILL LIKELY HASTEN DISSIPATION. DISSIPATION IS FORECAST NO LATER THAN TAU 48. MODEL DISCUSSION: DETERMINISTIC TRACK MODELS ARE IN DECENT AGREEMENT ON A SOUTHWESTWARD TRACK THROUGH TAU 24 BUT HAVE VARYING TRACK SPEEDS. THOUGH MOST MODELS AGREE ON A SOUTHEASTWARD CURVE BEGINNING AFTER TAU 24, THE TRACK SPEED DIFFERENCES GREATLY IMPACT THE LOCATION AT WHICH 02A WILL TURN, LENDING UNCERTAINTY TO THE JTWC TRACK FORECAST. OUTLIERS INCLUDE NAVGEM -- WHICH TRACKS 02A SOUTHWEST UNTIL TAU 48 BEFORE RECURVING, AND GFS -- WHICH IS THE ONLY MODEL PREDICTING A NORTHEASTERN CURVE. THE JTWC TRACK FORECAST IS PLACED SLIGHTLY EAST OF THE MULTI-MODEL CONSENSUS WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU 48, WITH ALL MODELS PREDICTING A CONSISTENT WEAKENING TREND BEGINNING IMMINENTLY WITH DISSIPATION FORECAST WITHIN 48 HOURS. AS A RESULT, THE JTWC INTENSITY FORECAST IS PLACED WITH HIGH CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM INTENSITY 00-72 HR: HIGH// NNNN