WTXS31 PGTW 290900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 07S (CHALANE) WARNING NR 010// RMKS/ 1. TROPICAL CYCLONE 07S (CHALANE) WARNING NR 010 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 290600Z --- NEAR 19.6S 39.9E MOVEMENT PAST SIX HOURS - 275 DEGREES AT 16 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT REPEAT POSIT: 19.6S 39.9E --- FORECASTS: 12 HRS, VALID AT: 291800Z --- 19.6S 37.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 265 DEG/ 13 KTS --- 24 HRS, VALID AT: 300600Z --- 19.7S 34.9E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 270 DEG/ 15 KTS --- 36 HRS, VALID AT: 301800Z --- 19.8S 31.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 290900Z POSITION NEAR 19.6S 39.3E. 29DEC20. TROPICAL CYCLONE 07S (CHALANE), LOCATED APPROXIMATELY 157 NM NORTH OF EUROPA ISLAND, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. THE SYSTEM HAS BEGUN TO ACCELERATE WESTWARD AS THE SUBTROPICAL RIDGE (STR) TO THE SOUTH BECAME THE DOMINANT STEERING FEATURE. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION HAS WEAKENED, BUT ALSO HAS BECOME MORE COMPACT, WRAPPING TIGHTER INTO THE LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A WARM CLUSTER OF PIXELS IN A NOTCH FEATURE IN THE EIR LOOP THAT IS STACKED VERTICALLY TO THE LLC. THE INITIAL INTENSITY IS BASED ON THE DVORAK ESTIMATE OF T3.0/45KTS FROM PGTW. ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW (<10KT) VERTICAL WIND SHEAR (VWS) AND VERY WARM (31C) SST IN THE MOZAMBIQUE CHANNEL, OFFSET BY A LACK OF UPPER LEVEL OUTFLOW, PREVENTING THE SYSTEM FROM SIGNIFICANT INTENSIFICATION. TC 07S WILL CONTINUE TO TRACK WESTWARD TOWARD MOZAMBIQUE UNDER THE STR, MAKING LANDFALL NEAR BEIRA BY TAU 24. LOW VWS AND WARM SST WILL FUEL FURTHER INTENSIFICATION TO A PEAK OF 60 KTS BY TAU 12. AFTERWARD, LAND INTERACTION WILL ERODE THE SYSTEM DOWN TO 50 KTS AFTER LANDFALL THEN RAPIDLY TOWARD DISSIPATION BY TAU 24 AFTER IT DRAGS ACROSS MOZAMBIQUE AND CROSSES INTO ZIMBABWE. NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH MINOR SPREADING TO 120NM BY TAU 36, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 290600Z IS 15 FEET. NEXT WARNINGS AT 292100Z AND 300900Z.// NNNN