TC 05S(BELAL) and TC 06S(ANGGREK) up-dates// 1615utc

JTWC IS ISSUING 12HOURLY WARNINGS ON TC 05S(BELAL) AND ON TC 06S(ANGGREK). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON BOTH SYSTEMS.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL CYCLONE (TC) 05S (BELAL) CONTINUING TO TRACK TOWARDS THE SOUTHWEST. ELEVATED MID- LEVEL WIND SHEAR (20-25KTS) HAS STEADILY DECOUPLED THE STORM OVER THE LAST TWELVE HOURS REVEALING AN OPEN LOW LEVEL CIRCULATION CENTER (LLCC) OFFSET TO THE NORTHWEST FROM THE UPPER-LEVEL CONVECTION. OUTFLOW ALOFT PRIMARILY FLOWS SOUTHEAST FROM THE DISLOCATED REGION OF UPPER-LEVEL CONVECTION. CLEAR REGIONS TO THE WEST OF BELAL WRAP INTO THE STORM AS DRY AIR CONTINUES TO ENGULF AND WEAKEN THE SYSTEM. SEA SURFACE TEMPERATURES (SST) UP TO 28C CONTINUE TO SUPPORT DEVELOPMENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE WITH SUPPORT FROM A 161146Z SSMIS 37GHZ SATELLITE MICROWAVE IMAGE THAT SHOWED A CLEAR-CUT MICROWAVE EYE-LIKE FEATURE. THE INITIAL INTENSITY OF 50KTS IS PLACED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF AGENCY SUBJECTIVE AND OBJECTIVE FIXES INCLUDING CIMSS AIDT ESTIMATE OF 48 KNOTS AND 161030Z SATCON ESTIMATE OF 51 KNOTS.

A CLEAR-CUT MICROWAVE EYE-LIKE FEATURE

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: TRUNCATING THE FORECAST AT TAU 72 AS THE STORM IS ANTICIPATED TO DISSIPATE. FORECAST DISCUSSION: TC 05S (BELAL) IS FORECAST TO TRACK EAST-SOUTHEAST THROUGH TAU 48 WHILE STEERED BY THE NER TO THE NORTHWEST. THE SYSTEM SLOWS DOWN SIGNIFICANTLY BY TAU 36 AS IT RUNS INTO A BUILDING RIDGE TO THE EAST WHICH EFFECTIVELY BLOCKS FURTHER EASTWARD PROGRESSION. AFTER TAU 48, TC BELAL WILL VEER SHARPLY SOUTHWEST AS THE NER TO THE NORTH WEAKENS AND THE STEERING INFLUENCE SHIFTS TO THE LOW- TO MID-LEVEL MID-LATITUDE RIDGE TO THE SOUTH. BELAL IS ANTICIPATED TO MAINTAIN 50 KNOT INTENSITY THROUGH TAU 24 AS COMPETING ENVIRONMENTAL FACTORS OFFSET ONE ANOTHER. BY TAU 24 HOWEVER, THE SYSTEM WILL EXPERIENCE A MORE RAPID WEAKENING TREND, AS WIND SHEAR IS ANTICIPATED TO INCREASE TO APPROXIMATELY 30KTS BY TAU 48 AND INCREASE TO 55-60KTS BY TAU 96. A RADIOSONDE SOUNDING FROM FMEE SHOWS THAT MOISTURE CEASES ABOVE 700MB, AND DRY AIR IS EXPECTED TO CONTINUE TO ENTRAIN INTO THE SYSTEM AND WEAKEN THE STORMS INTENSITY AS IT TRAVELS TO THE EAST SOUTH-EAST AND THEN WEST SOUTH-WEST. THE COMBINATION OF THE DRY AIR ENTRAINMENT AND THE MID LEVEL WIND SHEAR ARE ANTICIPATED TO OVERCOME THE FAVORABLE SST OF 26C AND DISSIPATE THE STORM BY TAU 72.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS GENERALLY IN GOOD AGREEMENT THROUGH TAU 36, SHOWING A FAIRLY WELL-CONSTRAINED CROSS-TRACK SPREAD OF JUST 50NM. HOWEVER, BY TAU 60 THE JTWC CONSENSUS MEMBERS DEVIATE 180 DEGREES, WITH UKMET REPRESENTING THE EAST BOUNDARY AND GFS ENSEMBLE ON THE WEST. BY TAU 72, NEARLY ALL MEMBERS SHOW THE SYSTEM TURNING BACK TOWARDS THE SOUTHWEST BUT VARY SHARPLY IN THE SPEED OF THE SOUTHWEST TRACK, LEADING TO A VERY WIDE MODEL SPREAD OF 350NM. INTENSITY GUIDANCE AGREES ON A STEADY-STATE FOR THE FIRST 24 HOURS, THEN ANTICIPATES A DECREASE STARTING AT TAU 24, DROPPING FROM 50KTS STEADILY TO 30KTS BY TAU 72, WHEN THE SYSTEM ULTIMATELY DISSIPATES.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE (TC) 06S (SIX) CONTINUING TO DEVELOP AS IT VERY SLOWLY TRACKS EASTWARD OVER THE PAST 12 HOURS. CENTRALIZED DEEP CONVECTION PERSISTS AND FORMATIVE SPIRAL BANDS OF DEEP CONVECTION ARE OBSERVED THROUGHOUT THE NORTHERN PERIPHERY OF THE SYSTEM. OUTFLOW ALOFT REMAINS CONDUCIVE FOR DEVELOPMENT, WITH EVIDENCE OF CIRRUS FILAMENTS DRIFTING BOTH EQUATORWARD AND POLEWARD ON ANIMATED EIR SATELLITE IMAGERY. WIND SHEAR IS FORECAST TO REMAIN LOW TO MODERATE (10-20 KTS) THROUGH TAU 96, WITH SUPPORTIVE SEA SURFACE TEMPERATURES (28-29 C) OVER THE SAME INTERVAL. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A 151544Z METOP-B SCATTEROMETER IMAGE. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED SCATTEROMETRY IMAGE, AS WELL AS THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 06S HAS BEGUN AN EASTWARD JAUNT AND WILL CONTINUE TO TRACK EASTWARD AT VERY SLOW TRACK SPEEDS OVER THE NEXT 12 TO 24 HOURS DUE TO A COMPETING STEERING ENVIRONMENT WITH RIDGING PREVALENT TO BOTH THE NORTH AND SOUTH. NEAR TAU 24, THE TC IS FORECAST TO SLOWLY TRACK SOUTHEASTWARD THROUGH TAU 36, AND EVENTUALLY COME TO A SOUTHWARD TRACK BY TAU 48. THE INTERVAL BETWEEN TAU 24 AND TAU 72 OFFERS THE MOST FAVORABLE CONDITIONS FOR TC INTENSIFICATION TO OCCUR, WITH INTENSITY PEAKING NEAR 65KTS AROUND TAU 60. FOLLOWING THE INTENSITY PEAK (TAU 72), SEA SURFACE TEMPERATURES BEGIN TO DROP AND VERTICAL WIND SHEAR INCREASES TO MODERATE LEVELS (20-25KTS) THROUGH TAU 120. AT TAU 72, AND AS ALLUDED TO IN THE MODEL DISCUSSION, A BIFURCATION BECOMES EVIDENT IN MODEL GUIDANCE. PRIMARILY, THIS IS DUE TO HOW DIFFERENT MODELS ARE RESOLVING THE WEAK STR TO THE SOUTH. SOME MODEL SOLUTIONS, SUCH AS ECMWF, SUGGEST THE RIDGE PROPAGATES EASTWARD, ALLOWING TC 06S TO TRACK ALONG THE WESTERN PERIPHERY OF THE RIDGE, RESULTING IN A SOUTHWESTWARD TRACK. OTHERS, LIKE THE GFS SOLUTION, KEEP THE STR QUASISTATIONARY TO THE SOUTH-SOUTHWEST OF TC 06S, RESULTING IN A MORE SOUTH-SOUTHEASTWARD TRACK THROUGH TAU 120.

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THAT TC 06S (SIX) WILL CONTINUE TO GRADUALLY AND SLOWLY TRACK EASTWARD OVER THE NEXT TWELVE HOURS. OVER THIS PERIOD, THE GFS AND HAFS-A SOLUTIONS EXHIBIT A SLIGHTLY FASTER TRACK SPEED, BRINGING THE LLCC AS FAR EAST AS 95E. AT THIS POINT (TAU 24), MODELS INDICATE THE SYSTEM WITH SLOWLY TURN TO A SOUTHEASTWARD COURSE (TAU 24 TO TAU 36) FOLLOWED BY A SOUTHWARD TRACK (TAU 48 TO TAU 27). BETWEEN TAU 24 AND TAU 72 IS WHEN INTENSITY GUIDANCE SUGGESTS INTENSIFICATION WILL STEADILY OCCUR, PEAKING NEAR TAU 60 AT 65KTS. HOWEVER, THERE IS A LARGE SPREAD (30 KTS) IN INTENSITY GUIDANCE AT TAU 60, LEAVING MODERATE (MEDIUM) UNCERTAINTY IN THE FORECAST. AFTER TAU 72, MODELS CONTINUE TO DIVERGE AND CREATE A BIFURCATION. THE GFS AND UKMET DETERMINISTIC AND ENSEMBLE MEAN SOLUTIONS SUGGEST THE TRACK WITH STEER SOUTHEASTWARD TO EASTWARD FORWARD OF TAU 72, WHILE THE REMAINING MEMBERS OF THE JTWC CONCENSUS STEER THE SYSTEM SOUTHWESTWARD TO WESTWARD. DUE TO THE LARGE UNCERTAINTY PRESENTED, THE FORECAST CONFIDENCE OF THE LATER INTERVAL IS LOW.