152100Z POSITION NEAR 18.6S 63.3E. TROPICAL CYCLONE (TC) 05S (BANSI), LOCATED APPROXIMATELY 335 NM EAST- NORTHEAST OF PORT LOUIS, MAURITIUS, HAS TRACKED EAST-SOUTHEASTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES A SLIGHT WEAKENING TREND WITH A 30-NM RAGGED EYE AND A MORE ASYMMETRIC APPEARANCE TO THE EYEWALL AND CONVECTIVE BANDING. THIS WEAKENING TREND IS CLEARLY EVIDENT IN A 151732Z METOP-B 89 GHZ IMAGE, WHICH SHOWS EROSION OF THE CONVECTIVE BANDING AND EYEWALL OVER THE SOUTHWESTERN SEMI-CIRCLE WITH DEEP CONVECTION DISPLACED OVER THE NORTHEAST SEMI-CIRCLE. UPPER-LEVEL ANALYSIS SHOWS INCREASED SOUTHWESTERLY VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH AN UPPER-LEVEL SHORTWAVE TROUGH IMPINGING ON THE SYSTEM. ADDITIONALLY, TC 05S IS NOW EMBEDDED WITHIN A BROAD AREA OF UPPER-LEVEL TROUGHING, WHICH SHOULD INHIBIT FURTHER INTENSIFICATION. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THE EYE. THE INITIAL INTENSITY IS ASSESSED AT 115 KNOTS BASED ON T6.0 (115 KNOTS) DVORAK ESTIMATES FROM ALL AGENCIES. TC 05S IS TRACKING EASTWARD TO EAST-SOUTHEASTWARD ALONG THE POLEWARD PERIPHERY OF THE NEAR-EQUATORIAL RIDGE BUT IS FORECAST TO TRANSITION TO THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE NEAR TAU 36, WHICH WILL ACCELERATE THE SYSTEM EAST-SOUTHEASTWARD TO SOUTHEASTWARD. DYNAMIC GUIDANCE REMAINS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. THE SYSTEM IS EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 48 AS IT INTERACTS WITH THE BAROCLINIC ZONE AND SHOULD COMPLETE ETT BY TAU 96. TC 05S IS EXPECTED TO WEAKEN SIGNIFICANTLY AFTER TAU 24 AS IT ENCOUNTERS INCREASING VWS AND COOLER SST. AFTER TAU 48, TC 05S WILL RAPIDLY WEAKEN AS IT UNDERGOES ETT. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 151800Z IS 35 FEET.
160300Z POSITION NEAR 19.6S 42.7E. TROPICAL CYCLONE (TC) 06S (CHEDZA), LOCATED APPROXIMATELY 736 NM WEST OF ST DENIS, HAS TRACKED EAST-SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES RAPID CONSOLIDATION WITH IMPROVED DEEP CONVECTIVE BANDING. A 152336Z SSMI IMAGE DEPICTS A WELL-DEFINED, PARTIALLY-EXPOSED LOW- LEVEL CIRCULATION CENTER POSITIONED ON THE NORTHWEST EDGE OF A DEEP CONVECTIVE BAND. RECENT SCATTEROMETER DATA INDICATES 35 TO 40 KNOT WINDS. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH GOOD EQUATORWARD OUTFLOW AND A DEVELOPING POLEWARD CHANNEL OVER THE SOUTHERN SEMI-CIRCLE OF THE LLCC. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THE AFOREMENTIONED SSMI IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS BASED ON AN AVERAGE OF DVORAK ESTIMATES RANGING FROM 35 TO 45 KNOTS. TC 06S IS TRACKING ALONG THE PERIPHERY OF THE NEAR-EQUATORIAL RIDGE (NER) AND IS FORECAST TO CONTINUE TRACKING EASTWARD THROUGH TAU 72. THE SYSTEM IS EXPECTED TO INTENSIFY, PRIOR TO LANDFALL NEAR TAU 12, TO A PEAK INTENSITY OF 50 KNOTS. THEREAFTER, THE SYSTEM WILL WEAKEN AS IT TRACKS OVER LAND. GRADUAL INTENSIFICATION IS EXPECTED AS THE SYSTEM RE-EMERGES OVER WATER AFTER TAU 40. DYNAMIC GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 72. AFTER TAU 72, THE SYSTEM WILL SLOW DUE TO COMPETING STEERING INFLUENCES, NAMELY, THE NER AND A BUILDING SUBTROPICAL RIDGE TO THE SOUTH. DYNAMIC GUIDANCE DIVERGES DUE TO UNCERTAINTIES IN THE STRENGTH AND ORIENTATION OF THE STEERING INFLUENCES. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE LARGE MODEL SPREAD IN THE EXTENDED TAUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 160000Z IS 10 FEET. NEXT WARNINGS AT 161500Z AND 170300Z. THIS WARNING SUPERSEDES AND CANCELS REF A JOINT TYPHOON WRNCEN PEARL HARBOR HI 151621Z JAN 15 TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 151630). REFER TO TROPICAL CYCLONE 05S (BANSI) WARNINGS (WTXS31 PGTW) FOR TWELVE-HOURLY UPDATES.// NNNN
- JTWC
