WTXS31 PGTW 252100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 07S (CHALANE) WARNING NR 003// RMKS/ 1. TROPICAL CYCLONE 07S (CHALANE) WARNING NR 003 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 251800Z --- NEAR 16.2S 53.7E MOVEMENT PAST SIX HOURS - 260 DEGREES AT 11 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT REPEAT POSIT: 16.2S 53.7E --- FORECASTS: 12 HRS, VALID AT: 260600Z --- 16.1S 52.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 260 DEG/ 08 KTS --- 24 HRS, VALID AT: 261800Z --- 16.3S 50.4E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 255 DEG/ 09 KTS --- 36 HRS, VALID AT: 270600Z --- 16.7S 48.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 245 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 271800Z --- 17.5S 46.5E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 245 DEG/ 10 KTS --- 72 HRS, VALID AT: 281800Z --- 19.0S 42.7E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 270 DEG/ 10 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 291800Z --- 18.8S 38.5E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 270 DEG/ 11 KTS --- 120 HRS, VALID AT: 301800Z --- 18.7S 33.8E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 252100Z POSITION NEAR 16.2S 53.3E. 25DEC20. TROPICAL CYCLONE (TC) 07S (CHALANE), LOCATED APPROXIMATELY 274 NM NORTH-NORTHWEST OF ST DENIS, LA REUNION, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH LIMITED DEEP CONVECTION SHEARED OVER THE SOUTHERN SEMICIRCLE. A 251523Z MHS 89GHZ MICROWAVE IMAGE REVEALS SHALLOW CONVECTIVE BANDING WRAPPING INTO A WEAKLY-DEFINED LLCC WITH ISOLATED DEEP CONVECTION OVER THE SOUTH QUADRANT. UPPER-LEVEL ANALYSIS INDICATES MARGINALLY-FAVORABLE CONDITIONS WITH EASTERLY DIFFLUENT FLOW OVER THE SYSTEM OFFSET BY LOW TO MODERATE (10 TO 20 KNOTS) VERTICAL WIND SHEAR. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 2.0-2.5 (30- 35 KNOTS). ADDITIONALLY, A 251650Z SCATSAT IMAGE REVEALED 30-35 KNOT WINDS OVER THE SOUTHERN SEMICIRCLE. TC 07S TRACKED DIRECTLY OVER SERGE FROLOW (61976) NEAR 13Z AND REPORTED MAXIMUM WINDS OF 25 KNOTS (1-MINUTE AVERAGE) AND A MINIMUM SLP VALUE OF 1000MB, WHICH REFLECTS THE WEAKER WINDS AND WEAKER CONVECTIVE STRUCTURE OVER THE NORTHERN SEMICIRCLE. TC 07S IS TRACKING ALONG THE NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTHEAST AND IS FORECAST TO GRADUALLY TURN WEST-SOUTHWESTWARD THROUGH TAU 72 AS IT APPROACHES A BREAK IN THE STR. AFTER TAU 72, A WESTERN STR IS FORECAST TO BUILD SOUTH OF THE SYSTEM, WHICH WILL LEAD TO A WESTWARD ACCELERATION IN THE TRACK. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A 150NM SPREAD IN SOLUTIONS AT TAU 72 SUPPORTING THE JTWC FORECAST TRACK WITH MODERATE CONFIDENCE. TC 07S IS FORECAST TO INTENSIFY TO 40 KNOTS PRIOR TO MAKING LANDFALL NEAR TAU 24 THEN WILL RAPIDLY WEAKEN AS IT TRACKS ACROSS MADAGASCAR. AS THE SYSTEM EMERGES OVER THE MOZAMBIQUE CHANNEL, TC 07S WILL RE-INTENSIFY GRADUALLY TO A PEAK OF 45 KNOTS UNDER FAVORABLE UPPER-LEVEL CONITIONS WITH WARM SST (31- 32C) VALUES. THE SYSTEM IS FORECAST TO DISSIPATE AS IT TRACKS OVER MOZAMBIQUE AFTER TAU 108. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 251800Z IS 15 FEET. NEXT WARNINGS AT 260900Z AND 262100Z.// NNNN