WTPS31 PGTW 050300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (DONNA) WARNING NR 006// RMKS/ 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 006 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 050000Z --- NEAR 13.1S 166.2E MOVEMENT PAST SIX HOURS - 250 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 13.1S 166.2E --- FORECASTS: 12 HRS, VALID AT: 051200Z --- 13.6S 165.3E 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 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 135 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 03 KTS --- 24 HRS, VALID AT: 060000Z --- 14.0S 164.8E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 105 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 190 DEG/ 03 KTS --- 36 HRS, VALID AT: 061200Z --- 14.5S 164.7E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 105 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 170 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 070000Z --- 15.2S 164.8E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 165 DEG/ 05 KTS --- 72 HRS, VALID AT: 080000Z --- 17.1S 165.3E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 145 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 145 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 090000Z --- 19.1S 166.8E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 145 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 135 DEG/ 06 KTS --- 120 HRS, VALID AT: 100000Z --- 20.7S 168.6E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT --- REMARKS: 050300Z POSITION NEAR 13.2S 166.0E. TROPICAL CYCLONE 18P (DONNA), LOCATED APPROXIMATELY 302 NM NORTH- NORTHWEST OF PORT VILA, VANUATU, HAS TRACKED WEST-SOUTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS WEAKENING CONVECTION AND WARMING CLOUD TOPS. THE INITIAL POSITION IS EXTRAPOLATED FROM A LOW REFLECTIVITY FEATURE IN A 042215Z AMSU-B IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON BOTH OBJECTIVE AND AGENCY CURRENT INTENSITY DVORAK ESTIMATES RANGING FROM 4.5 TO 5.0 (77 TO 90 KNOTS). ENVIRONMENTAL CONDITIONS HAVE DETERIORATED IN THE UPPER-LEVELS OVER THE LAST SIX HOURS DUE TO A POINT SOURCE ANALYZED TO THE NORTHEAST WHICH IS RESTRICTING OUTFLOW ON THE NORTH AND EASTERN QUADRANTS AND CREATING A MODERATE SHEAR ENVIRONMENT. STRONG POLEWARD DIFFLUENCE IS STILL EVIDENT IN SATELLITE IMAGERY TAPPING INTO THE MID-LATITUDE JET. SSTS ARE ALSO VERY WARM IN THE REGION, NEAR 30 CELSIUS. CURRENTLY TC DONNA IS TRACKING WEST-SOUTHWESTWARD GUIDED BY A SUBTROPICAL RIDGE TO THE SOUTH. A BREAK IN THE STEERING RIDGE IS EXPECTED IN THE NEXT 12 TO 24 HOURS SLOWING THE SYSTEM DOWN AS A RIDGE TO THE SOUTHWEST COMPETES WITH THE DOMINANT SOUTHEAST RIDGE. OVER THE NEXT 24 HOURS MODERATE SHEAR DUE TO NORTHEASTERLY FLOW ALOFT IS EXPECTED TO PERSIST AND WILL MITIGATE DEVELOPMENT. BEYOND TAU 24 A LONGWAVE TROUGH WILL MOVE INTO THE REGION ENHANCING OUTFLOW, AND PRIME TC DONNA FOR ANOTHER PERIOD OF INTENSIFICATION. PEAK INTENSITY IS EXPECTED TO REACH 110 BY TAU 48. THE APPROACHING TROUGH WILL ALSO ERODE THE WESTERN RIDGE AND THE SYSTEM WILL TURN AND BEGIN TO ACCELERATE TO THE SOUTHEAST AROUND TAU 48. HIGH WINDS ALOFT ASSOCIATED WITH THE TROUGH WILL INTRODUCE SIGNIFICANT VERTICAL WIND SHEAR AND BEGIN WEAKENING THE SYSTEM AFTER TAU 72. NUMERICAL MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT WITH THE TRACK TRAJECTORY, HOWEVER THERE IS STILL A LARGE DEGREE OF UNCERTAINTY IN THE EXACT POSITION AND TIMING TC DONNA WILL MAKE THE TURN TO THE SOUTHEAST. OVERALL, THE AVAILABLE GUIDANCE HAS SHIFTED THE TRACK TO THE WEST IN RECENT MODEL RUNS, AND THIS TREND IS BEGINNING TO STABILIZE, THUS IMPROVING CONFIDENCE IN THE FORECAST TRACK. DUE TO THE INHERENT UNCERTAINTY IN THE SOUTHWARD TURN, THERE IS OVERALL LOW CONFIDENCE IN THE FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 041800Z IS 28 FEET. NEXT WARNINGS AT 050300Z, 050900Z, 051500Z AND 052100Z.//