TC 01B(MOCHA) strong CAT 3 US to make landfall by 42h between COX'S BAZAR and SITTWE// Invest 92S// 1221utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 01B(MOCHA).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A BROAD, WELL ORGANIZED SYSTEM WITH A RAGGED EYE SURROUNDED BY BANDS OF DEEP CONVECTION IN ALL QUADRANTS WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). ANALYSIS OF MULTI-AGENCY 121800Z POSITIONS COMPARED TO PREVIOUS POSITIONS SUGGESTS THE SYSTEM HAS WOBBLED NORTHWARD. THIS BEHAVIOR IS USUALLY INDICATIVE OF A RAPIDLY STRENGTHENING SYSTEM. IN ADDITION, ANALYSIS OF THE M-PERC EYEWALL REPLACEMENT TOOL SUGGESTS AN EYEWALL REPLACEMENT CYCLE (ERC) IS UNDERWAY. ONE MAJOR CONTRIBUTING FACTOR TO THE RAPID INTENSIFICATION IS AN INTENSE POOL OF OCEAN HEAT CONTENT (OHC) THAT HAS DOMINATED THE CENTRAL BAY OF BENGAL OVER THE PAST SEVERAL DAYS. TC MOCHA IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER TROPICAL DEVELOPMENT. THESE CONDITIONS ARE CHARACTERIZED BY STRONG POLEWARD AND EQUATORWARD OUTFLOW ALOFT, A STRONG 850 MB VORTICITY SIGNATURE, MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), AND VERY WARM (30-31 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY FIXES, AS WELL AS THE AFOREMENTIONED EIR IMAGERY. THE INITIAL INTENSITY OF 110 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED OFF A BLEND OF MULTI-AGENCY DVORAKS ESTIMATES AND THE ABOVEMENTIONED RAPID INTENSIFICATION EXAMINATION.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: INCREASE OF INITIAL INTENSITY DUE TO RI. FORECAST DISCUSSION: TC 01B (MOCHA) IS RIDING THE WESTERN PERIPHERY OF THE STR TO THE EAST. AS PREVIOUSLY MENTIONED, TC MOCHA HAS RAPIDLY INTENSIFIED OVER THE PAST 6 HOURS. BETWEEN TAUS 12 AND 24, TC 01B WILL TRACK NORTHEASTWARD AND CONTINUE TO INTENSIFY TO 115 KTS AND 120 KTS RESPECTIVELY AS THE SYSTEM WILL CONTINUE TO STRENGTHEN. BY TAU 36, PRIOR TO LANDFALL JUST SOUTH OF THE BANGLADESH AND MYANMAR BORDER, TC MOCHA WILL DECREASE IN INTENSITY TO 100 KNOTS AS THE ENVIRONMENT WILL BECOME LESS FAVORABLE. THESE LESS FAVORABLE CONDITIONS ARE DEFINED BY AN INCREASE IN VWS, DRY AIR ENTRAINMENT WRAPPING INTO THE LLCC FROM THE SOUTHERN PERIPHERY, THE ONSET OF LAND INTERACTION, AND COOLER (28-29 C) SST. BY TAU 42, TC 01B WILL MAKE LANDFALL AND BEGIN ITS DISSIPATION PHASE. BETWEEN TAUS 48 AND 72, TC MOCHA WILL DISSIPATE DUE TO LAND INTERACTION OVER NORTHWEST MYANMAR.

MODEL DISCUSSION: THE DETERMINISTIC AND ENSEMBLE MODELS ALL AGREE THAT TC 01B WILL CONTINUE TO INTENSIFY AS IT TRANSITS NORTHEASTWARD THROUGH TAU 24, THEN WEAKEN ON OR BEFORE TAU 36 AS IT CONTINUES THE SAME TRAJECTORY. THE JTWC FORECAST TRACK CONSENSUS MEMBERS ARE IN TIGHT AGREEMENT WITH A 21 NM SPREAD AT TAU 12 THAT GRADUALLY INCREASES TO 94 NM JUST BEFORE LANDFALL. THE GFS, ECMWF AND NAVGEM TRACKS ARE ON THE POLEWARD SIDE OF THE CONSENSUS ENVELOPE, WHEREAS THE UK AND AFUM SOLUTIONS ARE ON THE EQUATORWARD SIDE. DUE TO THIS, THE JTWC TRACK IS PLACED SLIGHTLY LEFT OF CONSENSUS WITH HIGH CONFIDENCE THROUGHOUT THE FORECAST PERIOD. THE JTWC INTENSITY CONSENSUS IS ALSO IN GOOD AGREEMENT WITH ALL SOLUTIONS INDICATING A DECREASE IN INTENSITY PRIOR TO LANDFALL. THE GFS INTENSITY GUIDANCE IS THE OUTLIER SHOWING LOWER VALUES THROUGHOUT THE FORECAST PERIOD. THE JTWC INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE DUE TO THE SPREAD IN THE CONSENSUS MEMBERS AND THE RAPID INTENSIFICATION SCENARIO.

AN AREA OF CONVECTION (INVEST 92S) HAS PERSISTED NEAR 2.3S 86.6E, APPROXIMATELY 894 NM EAST-NORTHEAST OF DIEGO GARCIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS BROAD MID-TO-HIGH LEVEL CYCLONIC TURING WITH BUILDING CONVECTION OVER AN ASSESSED LOW LEVEL CIRCULATION (LLC). A PARTIAL 121204Z SSMIS 91GHZ PASS SHOWS EVIDENCE OF LOW LEVEL TURNING WITH FRAGMENTED BANDING ASSOCIATED WITH ISOLATED THUNDERSTORM ACTIVITY. ENVIRONMENTAL ANALYSIS SHOWS THAT 92S IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR DEVELOPMENT DEFINED BY STRONG WESTWARD AND POLEWARD OUTFLOW ALOFT, AN IMPRESSIVE 850MB VORTICITY SIGNATURE, MODERATE (15-25KTS) VERTICAL WIND SHEAR, AND WARM (29-30C) SEA SURFACE TEMPERATURES. THE GFS, NAVGEM, AND CMC DETERMINISTIC MODELS, ALONG WITH A FEW GEFS ENSEMBLE MEMBERS, INDICATE A DEVELOPING TROPICAL SYSTEM WITHIN 36-48 HOURS. WHEREAS THE EC AND ICON DETERMINISTIC MODELS, ALONG WITH A NUMBER OF ECENS ENSEMBLE MEMBERS, SHOW A DEVELOPING TROPICAL SYSTEM AFTER TAU 48. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

IMPRESSIVE 850MB VORTICITY SIGNATURE

THE GFS, NAVGEM, AND CMC DETERMINISTIC MODELS, ALONG WITH A FEW GEFS ENSEMBLE MEMBERS, INDICATE A DEVELOPING TROPICAL SYSTEM WITHIN 36-48 HOURS. WHEREAS THE EC AND ICON DETERMINISTIC MODELS, ALONG WITH A NUMBER OF ECENS ENSEMBLE MEMBERS, SHOW A DEVELOPING TROPICAL SYSTEM AFTER TAU 48.