WTXS31 PGTW 262100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 07S (CHALANE) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 07S (CHALANE) WARNING NR 005 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 261800Z --- NEAR 17.6S 49.7E MOVEMENT PAST SIX HOURS - 235 DEGREES AT 15 KTS POSITION ACCURATE TO WITHIN 045 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, SYNOPTIC DATA AND EXTRAPOLATION PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT REPEAT POSIT: 17.6S 49.7E --- FORECASTS: 12 HRS, VALID AT: 270600Z --- 18.2S 47.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 240 DEG/ 12 KTS --- 24 HRS, VALID AT: 271800Z --- 19.3S 45.5E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 240 DEG/ 10 KTS --- 36 HRS, VALID AT: 280600Z --- 20.4S 43.6E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 255 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 281800Z --- 20.8S 42.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 270 DEG/ 09 KTS --- 72 HRS, VALID AT: 291800Z --- 20.8S 38.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 270 DEG/ 12 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 301800Z --- 20.9S 32.8E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 265 DEG/ 13 KTS --- 120 HRS, VALID AT: 311800Z --- 21.2S 27.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 262100Z POSITION NEAR 17.8S 49.2E. 26DEC20. TROPICAL CYCLONE (TC) 07S (CHALANE), LOCATED APPROXIMATELY 148 NM EAST-NORTHEAST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED SOUTHWESTWARD AT 15 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS FLARING DEEP CONVECTION OBSCURING THE LOW LEVEL CIRCULATION CENTER (LLCC) AS THE SYSTEM MOVES TOWARDS MADAGASCAR. THE INITIAL POSITION IS BASED ON TURNING IN THE EIR ALONG WITH A 261834Z MHS 89 GHZ MICROWAVE IMAGE SHOWING CONVECTIVE BANDING WRAPPING INTO THE LLCC WITH THE MAJORITY OF THE DEEP CONVECTION LOCATED OVER THE WESTERN SEMICIRCLE. THE INITIAL INTENSITY IS ASSESSED AT 35 KTS, HEDGED SLIGHTLY HIGHER THAN A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T2.0 (30 KTS) BASED ON PERSISTENT CONVECTIVE STRUCTURE AND A FMEE DVORAK CURRENT INTENSITY ESTIMATE OF T2.5 (35 KTS). ADDITIONALLY, A 261835Z METOP-B PARTIAL ASCAT IMAGE REVEALS SMALL SWATHS OF 30-35 KT WINDS ON THE EASTERN PERIPHERY OF TC 07S. ENVIRONMENTAL ANALYSIS INDICATES MARGINALLY FAVORABLE CONDITIONS CONSISTING OF EASTERLY DIFFLUENT FLOW OVER THE SYSTEM, LOW TO MODERATE (5-15 KTS) VERTICAL WIND SHEAR (VWS), AND CONDUCIVE (27-28 CELSIUS) SEA SURFACE TEMPERATURES (SST). THE SYSTEM IS TRACKING SOUTHWESTWARD ALONG THE NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTHEAST. THE SYSTEM IS EXPECTED TO MAKE LANDFALL OVER MADAGASCAR IMMINENTLY AND THEN TRACK SOUTHWESTWARD, WEAKENING TO 25 KTS BY TAU 24 DUE TO LAND INTERACTION. BY TAU 36, TC 07S SHOULD EMERGE OVER WATER IN THE MOZAMBIQUE CHANNEL WHERE A BUILDING STR TO THE SOUTHWEST WILL TAKE OVER AS THE PRIMARY STEERING MECHANISM, DRIVING TC 07S GENERALLY WESTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. WITHIN THE CHANNEL, FAVORABLE ENVIRONMENTAL CONDITIONS OF LOW VWS AND WARM (29-30 CELSIUS) SST WILL ALLOW TC 07S TO RE-INTENSIFY TO A PEAK OF 45 KTS BY TAU 72. SHORTLY BEFORE TAU 96, THE SYSTEM IS EXPECTED TO MAKE FINAL LANDFALL NEAR BEIRA, MOZAMBIQUE WHERE INTERACTION WITH THE RUGGED TERRAIN WILL STEADILY WEAKEN THE SYSTEM AND LEAD TO DISSIPATION BY TAU 120. DUE TO THE SOUTHWESTWARD TRACK OVER THE PAST 12 HOURS, THE JTWC FORECAST TRACK HAS BEEN SHIFTED SOUTH AND PLACED SLIGHTLY NORTH OF THE MULTI-MODEL CONSENSUS. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE GENERAL SOUTHWESTWARD THEN WESTWARD TRACK OF THE SYSTEM. THUS, THERE IS OVERALL MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 261800Z IS 14 FEET. NEXT WARNINGS AT 270900Z AND 272100Z.// NNNN