WTPS31 PGTW 042100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (DONNA) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 005 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 041800Z --- NEAR 13.0S 166.8E MOVEMENT PAST SIX HOURS - 245 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 025 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: 13.0S 166.8E --- FORECASTS: 12 HRS, VALID AT: 050600Z --- 13.6S 165.8E 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: 240 DEG/ 04 KTS --- 24 HRS, VALID AT: 051800Z --- 14.0S 165.1E 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: 215 DEG/ 02 KTS --- 36 HRS, VALID AT: 060600Z --- 14.4S 164.8E 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: 180 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 061800Z --- 15.0S 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: 160 DEG/ 05 KTS --- 72 HRS, VALID AT: 071800Z --- 16.9S 165.6E 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: 150 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 081800Z --- 19.1S 166.9E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 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: 140 DEG/ 06 KTS --- 120 HRS, VALID AT: 091800Z --- 21.0S 168.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY 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: 042100Z POSITION NEAR 13.2S 166.5E. TROPICAL CYCLONE 18P (DONNA), LOCATED APPROXIMATELY 295 NM NORTH- NORTHWEST OF PORT VILA, VANUATU, HAS TRACKED WEST-SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS DEEP CENTRAL CONVECTION WITH A BROAD COLD OVERCAST LAYER. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A FORMING LOW LEVEL EYE FEATURE OBSERVED IN A 041650Z 37 GHZ SSMIS IMAGE. THE INITIAL INTENSITY IS BASED ON AGENCY DVORAK ESTIMATES RANGING FROM 4.5 TO 5.0 (77 TO 90 KNOTS). ENVIRONMENTAL CONDITIONS ARE CURRENTLY FAVORABLE SUPPORTING FURTHER INTENSIFICATION WITH SSTS NEAR 30 CELSIUS AND NEAR-RADIAL OUTFLOW ALOFT. A POINT SOURCE ANALYZED JUST TO THE NORTH IS CREATING SOME WIND SHEAR ON THE NORTHERN PERIPHERY, HOWEVER THE SYSTEM IS TRACKING IN-PHASE WITH THE DIRECTION OF THE SHEAR. 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. DURING THIS TIME FURTHER INTENSIFICATION IS EXPECTED AS A TROUGH MOVES IN FROM THE WEST ENHANCING OUTFLOW. TC DONNA WILL REACH PEAK INTENSITY OF 110 BY TAU 48. THE APPROACHING TROUGH WILL ERODE THE WESTERN RIDGE AND THE SYSTEM WILL TURN AND BEGIN TO ACCELERATE TO THE SOUTHEAST AROUND TAU 48. HIGH WINDS ALOFT WILL INTRODUCE VERTICAL WIND SHEAR AND BEGIN WEAKENING THE SYSTEM BY TAU 96. NUMERICAL MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT WITH THE TRACK TRAJECTORY, BUT THERE IS STILL A LARGE DEGREE OF UNCERTAINTY AS TO WHEN AND WHERE TC DONNA WILL MAKE THE TURN TO THE SOUTHEAST. OVERALL, THE AVAILABLE GUIDANCE HAS SHIFTED TO THE WEST IN RECENT MODEL RUNS, AND THE JTWC FORECAST TRACK REFLECTS THIS CHANGE. DUE TO THE LARGE UNCERTAINTY THERE IS LOW CONFIDENCE IN THE FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 041800Z IS 28 FEET. NEXT WARNINGS AT 050300Z, 050900Z, 051500Z AND 052100Z.//