WTXS31 PGTW 272100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 07S (CHALANE) WARNING NR 007// RMKS/ 1. TROPICAL CYCLONE 07S (CHALANE) WARNING NR 007 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 271800Z --- NEAR 19.2S 45.6E MOVEMENT PAST SIX HOURS - 240 DEGREES AT 11 KTS POSITION ACCURATE TO WITHIN 050 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 19.2S 45.6E --- FORECASTS: 12 HRS, VALID AT: 280600Z --- 20.0S 43.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 260 DEG/ 07 KTS --- 24 HRS, VALID AT: 281800Z --- 20.2S 42.4E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 270 DEG/ 09 KTS --- 36 HRS, VALID AT: 290600Z --- 20.2S 40.5E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 270 DEG/ 11 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 291800Z --- 20.2S 38.2E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 270 DEG/ 11 KTS --- 72 HRS, VALID AT: 301800Z --- 20.2S 33.5E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 96 HR POSIT: 270 DEG/ 13 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 311800Z --- 20.3S 27.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 272100Z POSITION NEAR 19.4S 45.2E. 27DEC20. TROPICAL CYCLONE (TC) 07S (CHALANE), LOCATED APPROXIMATELY 109 NM WEST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED WEST- SOUTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS EXPANSIVE DEEP CONVECTION OVER THE NORTHWEST QUADRANT OF AN OBSCURED LOW-LEVEL CIRCULATION. A 271411Z SSMIS 91GHZ COMPOSITE MICROWAVE IMAGE AND A 271813Z MHS 89GHZ MICROWAVE IMAGE INDICATE DEEP CONVECTIVE BANDING OVER THE NORTHERN SEMICIRCLE WRAPPING INTO A RAGGED BUT DEFINED CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH FAIR CONFIDENCE. MICROWAVE IMAGERY CONTINUES TO REVEAL AN ORGANIZED CONVECTIVE STRUCTURE DESPITE THE RECENT TRACK OVER THE RUGGED, MOUNTAINOUS TERRAIN OF MADAGASCAR. THE INITIAL INTENSITY IS CONSERVATIVELY ASSESSED AT 30 KNOTS CONSISTENT WITH THE AFOREMENTIONED BANDING STRUCTURE. TC 07S IS TRACKING ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED EAST OF MADAGASCAR BUT IS FORECAST TO TRANSITION TO THE WESTWARD STEERING INFLUENCE OF A STR POSITIONED SOUTH OF THE MOZAMBIQUE CHANNEL. NUMERICAL MODEL GUIDANCE IS IN BETTER AGREEMENT WITH A 70-80NM SPREAD IN SOLUTIONS FROM TAU 24 TO TAU 60, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. TC 07S IS EXPECTED TO STEADILY INTENSIFY UNDER FAVORABLE UPPER-LEVEL CONDITIONS OF LOW VERTICAL WIND SHEAR AND WARM SST (30-32C) AFTER TRACKING OVER THE MOZAMBIQUE CHANNEL NEAR TAU 12. THERE IS UNCERTAINTY IN THE PEAK INTENSITY WITH SOME POTENTIAL FOR A SHORT PERIOD OF RAPID INTENSIFICATION AFTER TAU 24. THE PEAK INTENSITY HAS BEEN INCREASED TO 65 KNOTS AT TAU 48 WITH POTENTIAL FOR A HIGHER INTENSITY BEFORE LANDFALL NEAR TAU 66, SOUTH OF BEIRA. THE ECMWF AND GFS ENSEMBLES CONTINUE TO INDICATE POTENTIAL FOR MODERATE TO RAPID INTENSIFICATION (RI) WITH HWRF ALSO INDICATING RI. NEXT WARNINGS AT 280900Z AND 282100Z.// NNNN