WTXS31 PGTW 260900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 07S (CHALANE) WARNING NR 004// RMKS/ 1. TROPICAL CYCLONE 07S (CHALANE) WARNING NR 004 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 260600Z --- NEAR 16.1S 52.4E MOVEMENT PAST SIX HOURS - 260 DEGREES AT 07 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE 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 065 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT REPEAT POSIT: 16.1S 52.4E --- FORECASTS: 12 HRS, VALID AT: 261800Z --- 16.4S 50.6E 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 050 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 255 DEG/ 11 KTS --- 24 HRS, VALID AT: 270600Z --- 17.0S 48.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 245 DEG/ 12 KTS --- 36 HRS, VALID AT: 271800Z --- 18.0S 46.2E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 240 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 280600Z --- 18.9S 44.4E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 260 DEG/ 08 KTS --- 72 HRS, VALID AT: 290600Z --- 19.4S 41.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 270 DEG/ 11 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 300600Z --- 19.4S 36.5E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 265 DEG/ 13 KTS --- 120 HRS, VALID AT: 310600Z --- 19.7S 31.0E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 260900Z POSITION NEAR 16.2S 51.9E. 26DEC20. TROPICAL CYCLONE 07S (CHALANE), LOCATED APPROXIMATELY 327 NM EAST-NORTHEAST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A PARTIALLY-EXPOSED LOW LEVEL CIRCULATION (LLC) WITH SHALLOW, POORLY-ORGANIZED CONVECTION SHEARED SOUTHWARD. THE INITIAL POSITION IS BASED ON THE LLC FEATURE IN THE MSI LOOP. THE INITIAL INTENSITY OF 35KTS IS HEDGED HIGHER THAN AGENCY DVORAK ESTIMATES OF T2.0/30KTS TO REFLECT THE SUSTAINED 12-HR CONVECTIVE STRUCTURE. UPPER-LEVEL ANALYSIS INDICATES MARGINALLY- FAVORABLE CONDITIONS WITH EASTERLY DIFFLUENT FLOW OVER THE SYSTEM OFFSET BY LOW TO MODERATE (10-20KT) VERTICAL WIND SHEAR. ALONG-TRACK SEA SURFACE TEMPERATURE (SST) AT 28C IS ALSO CONDUCIVE. TC 07S WILL TRACK MORE WEST-SOUTHWESTWARD ALONG THE NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR), MAKING LANDFALL OVER NORTHEASTERN MADAGASCAR AROUND TAU 18 AND TRACK ACROSS THE ISLAND. AFTER TAU 48, IT WILL RESUME A WESTWARD TRAJECTORY AFTER IT EXITS INTO THE MOZAMBIQUE CHANNEL AS A WESTERN STR IS FORECAST TO BUILD SOUTH OF THE SYSTEM AND ASSUME STEERING. TC CHALANE WILL MAKE LANDFALL JUST NORTH OF BEIRA, MOZAMBIQUE SHORTLY AFTER TAU 96. THE MARGINAL ENVIRONMENT IN THE SOUTH INDIAN OCEAN WILL SUSTAIN ITS CURRENT INTENSITY PRIOR TO LANDFALL INTO MADAGASCAR. AFTERWARD THE RUGGED TERRAIN WILL REDUCE IT TO 25KTS. UNDER FAVORABLE UPPER-LEVEL CONDITIONS AND WARM SST (31-32C), THE CYCLONE WILL REGAIN INTENSITY OF 35KTS AFTER IT EMERGES IN THE MOZAMBIQUE CHANNEL THEN PEAK TO 45KTS PRIOR TO THE FINAL LANDFALL INTO MOZAMBIQUE. AFTERWARD, IT WILL DISSIPATE BY TAU 120 MOSTLY DUE TO LAND INTERACTION. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT LENDING MODERATE CONFIDENCE TO THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 260600Z IS 15 FEET. NEXT WARNINGS AT 262100Z AND 270900Z.// NNNN