WDIO31 PGTW 120300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (BIPARJOY) WARNING NR 024// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.4N 67.7E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 326 NM SOUTH OF KARACHI, PAKISTAN MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 36 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RAGGED CENTRAL DENSE OVERCAST (CDO), WITH CURVED BANDING FEATURES ALONG THE SOUTHERN PERIPHERY OF THE CIRCULATION. CLOUD TOP TEMPERATURES HAVE WARMED CONSIDERABLY OVER THE PAST SIX HOURS OR SO, INDICATIVE OF A GENERALIZED WEAKENING OF THE CONVECTION, EVEN AS WE APPROACH THE DIURNAL CONVECTIVE MAXIMUM. A RECENT AMSR2 36GHZ IMAGE FROM 112045Z SHOWED A SOLID RING OF DEEP CONVECTION ALONG THE SOUTHERN FLANK OF THE SYSTEM, WITH A VERY WEAK EYEWALL OF LIMITED AREAL EXTENT ALONG THE EAST AND NORTHEAST FLANKS. RECENT HWRF CROSS-SECTIONS AND CIMSS UPPER-LEVEL DIVERGENCE GRAPHICS SUGGESTS THE PRESENCE OF LARGE-SCALE CONVERGENCE ALOFT AND DOWNWARD VERTICAL MOTION TO THE NORTHEAST OF THE SYSTEM, AND THE MICROWAVE IMAGERY SEEMS TO BEAR THIS OUT. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE EVEN THOUGH THE LLCC IS OBSCURED, THROUGH EXTRAPOLATION OF THE MICROWAVE EYE SEEN IN THE 36GHZ AMSR2 IMAGE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, AS THERE IS STILL A LARGE SPREAD ACROSS THE SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES BETWEEN T4.5 (77 KTS) AND T5.0 (90 KTS) AND THE OBJECTIVE ESTIMATES BETWEEN 60-70 KTS. THE AMSR2 WINDSPEED PRODUCT SHOWED WINDS UP TO 97 KNOTS IN THE STRONG CONVECTION TO THE SOUTH OF THE CENTER BUT OTHERWISE A MUCH BROADER REGION OF 80-90 KNOT WINDS. THE SYSTEM IS STILL MOVING SLOWLY NORTH-NORTHWESTWARD ALONG THE WESTERN SIDE OF THE SUBTROPICAL RIDGE (STR) OVER INDIA. NO CHANGE IS SEEN IN THE ENVIRONMENT, STILL CHARACTERIZED AS MARGINALLY FAVORABLE, WITH HIGH VWS BEING OFFSET BY STRONG EQUATORWARD OUTFLOW AND VERY WARM SSTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER STR OVER INDIA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS KNES: T4.5 - 77 KTS DEMS: T5.0 - 90 KTS CIMSS SATCON: 70 KTS AT 112140Z CIMSS ADT: 59 KTS AT 112100Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 25-30 KTS SST: 30-31 CELSIUS OUTFLOW: STRONG EQUATORWARD 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: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST TRACK, AS THE OVERALL STEERING PATTERN IS RELATIVELY STABLE IN THE GLOBAL MODEL FIELDS. THE ONLY CHANGE IS A POTENTIAL SLOW DOWN IN THE TRACK SPEEDS AFTER TAU 48 IN MOST OF THE MODEL FIELDS AS THE RIDGE BUILDING IN FROM THE WEST LOOKS TO POTENTIALLY BE A BIT WEAKER THAN ANTICIPATED. LANDFALL IS STILL EXPECTED NEAR THE RANN OF KUTCH BUT THE TIMELINE HAS SHIFTED A FEW HOURS LATER. THE INTENSITY FORECAST REMAINS EXCEPTIONALLY CHALLENGING WITH A WIDE DIVERGENCE IN THE AVAILABLE GUIDANCE AND HIGH UNCERTAINTY IN THE INITIAL STARTING INTENSITY. HOWEVER, IN LIGHT OF THE HWRF DATA, THE CIMSS DIVERGENCE INFORMATION AND THE OVERALL STRUCTURAL TRENDS EVIDENT IN THE SATELLITE IMAGERY, IT APPEARS UNLIKELY THAT WE WILL SEE MUCH IN THE WAY OF SIGNIFICANT INTENSIFICATION FROM HERE ON OUT. GLOBAL MODELS SUGGEST AND INCREASE IN THE CONVERGENT FLOW ALOFT WHICH WILL IMPART SIGNIFICANT PRESSURE ON THE SYSTEM FROM THE NORTHEAST SIDE AND STEADILY INCREASE THE VORTEX TILT. THIS PROCESS ALONE SHOULD SUPPRESS ANY THOUGHTS OF INTENSIFICATION. IN ADDITION, THE SYSTEM WILL BEGIN TO ENTRAIN DRY DESERT AIR FROM INTERIOR PAKISTAN INTO THE WESTERN FLANK AS IT NEARS THE COASTLINE, INHIBITING CONVECTIVE DEVELOPMENT. HENCE THE FORECAST CALLS FOR A STEP-WISE WEAKENING TREND THROUGH TAU 48, FOLLOWED BY A SLIGHTLY FASTER PACED WEAKENING DUE TO THE IMPACT OF THE DRY AIR THROUGH TAU 72. THE SYSTEM IS STILL EXPECTED TO BE A MINIMAL TYPHOON STRENGTH SYSTEM AT LANDFALL BUT WILL RAPIDLY DISSIPATE ONCE ASHORE. MODEL DISCUSSION: NO SIGNIFICANT CHANGE HAS BEEN SEEN IN THE CONSENSUS TRACK ENVELOPE OVER THE PAST SEVERAL RUNS, WITH ALL OF THE MEMBERS CONTINUING TO SHOW A NORTH-NORTHWEST TRACK THROUGH TAU 48 FOLLOWED BY A SHARP TURN TO THE EAST-NORTHEAST THEREAFTER. GFS HAS SEPARATED FROM THE PACK, OUT A LITTLE FURTHER TO THE WEST, WITH THIS RUN AND DEPICTS A LANDFALL RIGHT ON THE PAKISTAN-INDIA BORDER. THE UKMET AND ECMWF ENSEMBLE MEAN ARE ON THE RIGHT EDGE OF THE ENVELOPE, TRACKING OVER THE WESTERN EDGE OF THE GULF OF KUTCH. OVERALL THE ENVELOPE, WHILE REMAINING FAIRLY TIGHT HAS SHIFTED SLIGHTLY WESTWARD SINCE THE LAST RUN. THE JTWC FORECAST REMAINS GENERALLY CONSISTENT WITH THE PREVIOUS FORECAST, BUT HAS SHIFTED SLIGHTLY WEST. CONFIDENCE REMAINS MEDIUM FOR THE ENTIRE FORECAST PERIOD. INTENSITY GUIDANCE REMAINS VERY UNCERTAIN, WITH A VERY LARGE SPREAD. HWRF CONTINUES TO BE VERY EXCITED ABOUT TC 02A, AND TRIES TO BRING A PEAK OF 120 KNOTS AT TAU 12, AS DOES THE RIDE RAPID INTENSIFICATION (RI) AID. THE REST OF THE GUIDANCE HOWEVER DOES NOT BELIEVE THIS IS POSSIBLE AND SHOWS EITHER A SLOW WEAKENING OR IN THE CASE OF THE SHIPS, RAPID WEAKENING THROUGH THE FORECAST. IN LIGHT OF THE HIGH UNCERTAINTY, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN