WTPS31 PGTW 040900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (DONNA) WARNING NR 004// RMKS/ 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 004 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 040600Z --- NEAR 12.4S 168.1E MOVEMENT PAST SIX HOURS - 280 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 015 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 000 NM NORTHEAST QUADRANT 015 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT REPEAT POSIT: 12.4S 168.1E --- FORECASTS: 12 HRS, VALID AT: 041800Z --- 12.8S 167.1E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 235 DEG/ 05 KTS --- 24 HRS, VALID AT: 050600Z --- 13.4S 166.2E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 210 DEG/ 04 KTS --- 36 HRS, VALID AT: 051800Z --- 14.1S 165.8E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 180 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 060600Z --- 14.7S 165.8E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 165 DEG/ 03 KTS --- 72 HRS, VALID AT: 070600Z --- 15.9S 166.1E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 150 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 080600Z --- 18.0S 167.3E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 145 DEG/ 06 KTS --- 120 HRS, VALID AT: 090600Z --- 19.9S 168.8E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT --- REMARKS: 040900Z POSITION NEAR 12.5S 167.8E. TROPICAL CYCLONE (TC) 18P (DONNA), LOCATED APPROXIMATELY 318 NM NORTH OF PORT VILA, VANUATU, HAS TRACKED WESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS CONTINUED TO DEEPEN AS SPIRAL BANDS CURVED TIGHTER INTO THE CENTER. THE INITIAL POSITION IS BASED ON A DIMPLE FEATURE IN THE MSI LOOP THAT LINES UP WELL WITH A LOW REFLECTIVITY CIRCULATION FEATURE IN THE 040442Z AMSU MICROWAVE PASS. THE INITIAL INTENSITY IS BASED ON AN OVERALL ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK ESTIMATES RANGING FROM T4.5 TO T4.6 AND REFLECTS THE DEEPENED STATE OF THE CYCLONE. ENVIRONMENTAL ANALYSIS INDICATES A VERY FAVORABLE ENVIRONMENT WITH WARM SSTS NEAR 30 CELSIUS AND EXCELLENT RADIAL OUTFLOW ALOFT. THERE IS LIGHT TO MODERATE ALONG-TRACK VERTICAL WIND SHEAR (VWS) BUT IS MOSTLY OFFSET BY THE OUTFLOW AND THE STORM MOTION THAT IS IN-PHASE WITH THE UPPER LEVEL WIND FLOW. TC DONNA IS TRACKING ALONG THE NORTHERN PERIPHERY OF A BUILDING SUBTROPICAL RIDGE (STR) TO THE SOUTH. AFTER TAU 36, A MID-LATITUDE TROUGH APPROACHING FROM THE SOUTHWEST IS EXPECTED TO WEAKEN THE STR AND CAUSE THE CYCLONE TO TRACK POLEWARD THEN ACCELERATE SOUTHEASTWARD. AS FAVORABLE CONDITIONS PERSIST IN THE NEAR- TO MID-TERM, THE SYSTEM WILL CONTINUE TO INTENSIFY, PEAKING AT 110 KNOTS NEAR TAU 72. AFTERWARD, INCREASING VWS AND COOLING SSTS WILL GRADUALLY WEAKEN THE CYCLONE. NUMERICAL MODEL GUIDANCE SHOWS OVERALL IMPROVED AGREEMENT WITH GFDN AS THE SOLE WESTWARD OUTLIER. THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE JUST EAST OF THE MULTI-MODEL CONSENSUS TO OFFSET GFDN. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 040600Z IS 24 FEET. NEXT WARNINGS AT 042100Z AND 050900Z.//