TY 03W(GUCHOL)// TC 02A(BIPARJOY)// TC 03B// 0915utc updates

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TY 03W(GUCHOL), TC 02A(BIPARJOY) AND TC 03B.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A RAGGED, CLOUD-FILLED EYE WITH INTENSE CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE AND WEAKER BANDING OVER THE WESTERN SEMICIRCLE. A 091246Z GMI 89GHZ MICROWAVE IMAGE REFLECTS A GENERAL WEAKENING TREND WITH AN ERODING EYEWALL OVER THE WESTERN QUADRANT AND THE BULK OF THE DEEP CONVECTIVE BANDING OVER THE EASTERN AND SOUTHERN SEMICIRCLES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE GMI 37GHZ IMAGE SHOWING A WELL-DEFINED MICROWAVE EYE. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW AND A ROBUST EASTWARD OUTFLOW CHANNEL INTO A STRONG UPPER LOW POSITIONED OVER THE NORTHERN MARIANAS. SST VALUES REMAIN FAVORABLE AT 28C, HOWEVER, OCEAN HEAT CONTENT VALUES ARE LOW REFLECTING A SHALLOW WARM LAYER. THE INITIAL INTENSITY OF 80 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE DVORAK CURRENT INTENSITY ESTIMATES AS WELL AS AN AIDT ESTIMATE OF 82 KNOTS. RECENT DMINT AND DPRINT OBJECTIVE INTENSITY ESTIMATES HAVE FLUCTUATED BETWEEN 80 TO 90 KNOTS.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 03W IS FORECAST TO RECURVE POLEWARD AROUND THE WESTERN PERIPHERY OF THE STR OVER THE NEXT 12 TO 24 HOURS WITH GRADUAL WEAKENING EXPECTED AFTER TAU 12. AFTER TAU 36, THE SYSTEM WILL ACCELERATE ALONG THE NORTHWEST PERIPHERY OF THE STR WITHIN THE SUBTROPICAL WESTERLIES, WHICH WILL EVENTUALLY LEAD TO SUBTROPICAL TRANSITION (STT) BY TAU 72. THE FRONTAL ZONE IS EXPECTED TO REMAIN WELL TO THE NORTH, THEREFORE, EXTRA-TROPICAL TRANSITION IS UNLIKELY SOUTH OF HONSHU. AFTER TAU 72, ENVIRONMENTAL CONDITIONS WILL DEGRADE FURTHER WITH INCREASING VERTICAL WIND SHEAR (20-50 KNOTS) AND COOLING, MARGINAL SST VALUES (25 TO 20C). AS TY 03W TRACKS MORE POLEWARD, IT WILL INTERACT WITH THE SUBTROPICAL JET AND COMPLETE STT BY TAU 96.

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 95NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72 LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. AFTER TAU 72, DETERMINISTIC GUIDANCE DIVERGES WITH INCREASING CROSS-TRACK AND ALONG-TRACK SPREAD PROVIDING MEDIUM CONFIDENCE. THE SYSTEM IS NOT EXPECTED TO IMPACT HONSHU DUE TO THE PRESENCE OF A STRONG JET OVER AND TO THE SOUTH OF HONSHU.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A STEADILY WEAKENING CONVECTIVE CORE WITH A CLUSTER OF FLARING DEEP CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION (LLC). EIR ALSO SHOWS A SECOND CLUSTER OF DEEP CONVECTION SEPARATED FROM THE CORE CONVECTION AND DISPLACED OVER THE WESTERN PERIPHERY OF THE SYSTEM. A 091146Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS DISORGANIZED CORE CONVECTION SHEARED WESTWARD OF A PARTIALLY-EXPOSED LLC WITH A CURVED CONVECTIVE BAND DISCONNECTED TO THE WEST. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE SSMIS IMAGE. UPPER-LEVEL ANALYSIS CONTINUES TO INDICATE MODERATE TO HIGH EASTERLY VERTICAL WIND SHEAR (VWS) OFFSET SOMEWHAT BY BROAD DIFFLUENCE ALOFT. THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW DATA-T ESTIMATE OF T3.5 (55 KNOTS) AND AN AIDT OBJECTIVE ESTIMATE OF 62 KNOTS. DVORAK CURRENT INTENSITY ESTIMATES FROM ALL THREE AGENCIES ARE SLIGHTLY HIGHER AT 65 KNOTS.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 02A IS STRUGGLING TO CONSOLIDATE DUE TO THE PERSISTENT MODERATE TO HIGH EASTERLY VWS. MODERATE WESTWARD OUTFLOW AND VERY WARM SEA SURFACE TEMPERATURES HAVE HELPED MAINTAIN THE INCREASINGLY DISORGANIZED, UNIMPRESSIVE CORE CONVECTION. GLOBAL MODELS HAVE BEGUN TO BACK OFF ON THE DECREASING VWS SCENARIO AND NOW INDICATE PERSISTENT MODERATE TO HIGH VWS, THEREFORE, THE PEAK INTENSITY HAS BEEN DECREASED TO 80 KNOTS AT TAU 36 AND WILL LIKELY BE LOWERED FURTHER. TC 02A IS MEANDERING POLEWARD SLOWLY AND WILL CONTINUE TRACKING NORTHWARD TO NORTH-NORTHEASTWARD THROUGH TAU 72. AFTER TAU 36, VWS IS FORECAST TO INCREASE SLIGHTLY WITH UPPER-LEVEL EASTERLIES STRENGTHENING SOUTH OF A BUILDING RIDGE TO THE NORTH. THIS IS EXPECTED TO PRODUCE A STEADY WEAKENING TREND THROUGH TAU 120 AS THE SYSTEM CONTINUES TO SLOWLY TRACK NORTH-NORTHWESTWARD INTO THE NORTHERN ARABIAN SEA.

MODEL DISCUSSION: IN GENERAL, DETERMINISTIC GUIDANCE HAS COME INTO BETTER AGREEMENT WITH GFS AND NAVGEM, IN PARTICULAR, ALIGNED CLOSER TO THE ECMWF AND ECMWF ENSEMBLE MEAN SOLUTIONS. HOWEVER, THERE IS STILL A 170NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72 AND A LARGE 385NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 120 REFLECTING INCREASING UNCERTAINTY (LOW CONFIDENCE) IN THE EXTENDED JTWC FORECAST TRACK. THE 090600Z ECMWF AND GFS ENSEMBLES ARE ALSO BETTER ALIGNED BUT ALSO REFLECT INCREASING UNCERTAINTY IN THE TRACK FORECAST AFTER TAU 72. THERE IS ALSO MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST THROUGH TAU 72 WITH A LARGE SPREAD IN RELIABLE INTENSITY GUIDANCE. SEVERAL MODELS HAVE INDICATED AND CONTINUE TO INDICATE SOME POTENTIAL FOR A SHORT PERIOD OF RAPID INTENSIFICATION WITHIN THE NEXT 36 HOURS. THE 090600Z COAMPS-TC ENSEMBLE INDICATES INCREASING PROBABILITIES OF RAPID INTENSIFICATION FROM 80 TO 90 PERCENT DURING THE NEXT 36 HOURS.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH DEEP CONVECTION FLARING OVER THE WESTERN SEMICIRCLE. A 091004Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS A LINEAR BAND OF DEEP CONVECTION SHEARING WESTWARD WITH A WEAKLY DEFINED LLC NEAR THE EASTERN EDGE OF THE BAND. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE EIR IMAGERY AND THE SSMIS IMAGE. ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY UNFAVORABLE ENVIRONMENT WITH HIGH (25-30 KNOTS) EASTERLY VERTICAL WIND SHEAR AND BROAD DIFFLUENCE ALOFT. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A RECENT 090355Z ASCAT-B BULLSEYE IMAGE SHOWING A SWATH OF 35 TO 40 KNOT WINDS OVER THE SOUTHERN SEMICIRCLE. DVORAK INTENSITY ESTIMATES REMAIN TOO LOW HOWEVER THE CIMSS ADT ESTIMATE OF 41 KNOTS IS SUPPORTIVE.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 03B IS FORECAST TO TRACK NORTHEASTWARD TO NORTH-NORTHEASTWARD ALONG THE NORTHWESTERN FLANK OF THE STEERING FLOW THROUGH THE FORECAST PERIOD. DUE TO THE MARGINALLY UNFAVORABLE ENVIRONMENTAL CONDITIONS, THE SYSTEM IS NOT EXPECTED TO INTENSIFY BUT SHOULD STEADILY WEAKEN AS IT APPROACHES THE MYANMAR COAST WITH DISSIPATION OCCURRING WITHIN THE NEXT 24 HOURS.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS VERY LIMITED WITH HWRF, ECMWF AND GFS SUPPORTING THE JTWC FORECAST TRACK INTO MYANMAR. THE 090000Z GFS ENSEMBLE (GEFS) SHOWS THE BULK OF SOLUTIONS TRACKING THE SYSTEM INTO MYANMAR WITH NO SIGNIFICANT DEVELOPMENT. THE 081800Z ECMWF ENSEMBLE (EPS) IS MORE LIMITED WITH A SPARSE SET OF SOLUTIONS TRACKING THE WEAK SYSTEM NORTHEASTWARD TO NORTH-NORTHEASTWARD. DUE TO THE LACK OF GUIDANCE, THE CONFIDENCE IN BOTH THE JTWC TRACK AND INTENSITY FORECAST IS MEDIUM.