WTIO31 PGTW 021500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 04A (CHAPALA) WARNING NR 020// RMKS/ 1. TROPICAL CYCLONE 04A (CHAPALA) WARNING NR 020 01 ACTIVE TROPICAL CYCLONE IN NORTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 021200Z --- NEAR 13.4N 50.7E MOVEMENT PAST SIX HOURS - 275 DEGREES AT 10 KTS POSITION ACCURATE TO WITHIN 010 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT REPEAT POSIT: 13.4N 50.7E --- FORECASTS: 12 HRS, VALID AT: 030000Z --- 13.7N 48.9E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 300 DEG/ 07 KTS --- 24 HRS, VALID AT: 031200Z --- 14.4N 47.7E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 36 HR POSIT: 315 DEG/ 03 KTS --- 36 HRS, VALID AT: 040000Z --- 14.9N 47.2E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 021500Z POSITION NEAR 13.5N 50.3E. TROPICAL CYCLONE (TC) 04A (CHAPALA), LOCATED APPROXIMATELY 110 NM EAST-SOUTHEAST OF MUKALLA, YEMEN, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED A 15-NM EYE AND OVERALL CONVECTIVE STRUCTURE. THE INITIAL POSITION IS BASED WITH HIGH CONFIDENCE ON THE EYE FEATURE AND LINED UP WITH THE LOW REFLECTIVITY MICROWAVE EYE IN THE 021059Z SSMI PASS. THE INITIAL INTENSITY IS BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM REPORTING AGENCIES. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF MODERATE 15-KNOT SOUTHERLY VERTICAL WIND SHEAR (VWS) THAT IS MOSTLY OFFSET BY EXCELLENT RADIAL OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). IT IS EXPECTED TO MAINTAIN ITS CURRENT TRACK UP TO TAU 12 BEFORE MAKING LANDFALL IN CENTRAL YEMEN JUST WEST OF MUKALLA BEFORE MAKING A NORTHWESTWARD TURN ALONG THE SOUTHWESTERN EDGE OF THE STR. TC CHAPALA WILL BEGIN TO WEAKEN AS DRY AIR EMANATING FROM THE ARABIAN PENINSULA, IN ADDITION TO INCREASING VWS, ERODES THE SYSTEM. THE CYCLONE WILL THEN RAPIDLY DECAY AFTER LANDFALL - LEADING TO DISSIPATION BY END OF FORECAST - MAINLY DUE TO LAND INTERACTION WITH THE RUGGED AND DRY YEMENI TERRAIN. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 021200Z IS 30 FEET. NEXT WARNINGS AT 022100Z, 030300Z, 030900Z AND 031500Z.//