WTXS32 PGTW 092100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 04S (IRVING) WARNING NR 016// RMKS/ 1. TROPICAL CYCLONE 04S (IRVING) WARNING NR 016 03 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 091800Z --- NEAR 23.9S 70.5E MOVEMENT PAST SIX HOURS - 225 DEGREES AT 20 KTS POSITION ACCURATE TO WITHIN 025 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 175 NM SOUTHEAST QUADRANT 180 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT REPEAT POSIT: 23.9S 70.5E --- FORECASTS: 12 HRS, VALID AT: 100600Z --- 27.1S 68.7E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 200 NM NORTHEAST QUADRANT 225 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 180 DEG/ 23 KTS --- 24 HRS, VALID AT: 101800Z --- 31.7S 68.6E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 195 NM NORTHEAST QUADRANT 200 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 155 DEG/ 36 KTS --- 36 HRS, VALID AT: 110600Z --- 38.2S 72.1E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 034 KT WINDS - 265 NM NORTHEAST QUADRANT 215 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 240 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 155 DEG/ 38 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 111800Z --- 44.9S 77.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 360 NM NORTHEAST QUADRANT 225 NM SOUTHEAST QUADRANT 385 NM SOUTHWEST QUADRANT 375 NM NORTHWEST QUADRANT --- REMARKS: 092100Z POSITION NEAR 24.7S 70.0E. TROPICAL CYCLONE 04S (IRVING), LOCATED APPROXIMATELY 769 NM EAST- SOUTHEAST OF PORT LOUIS, MAURITIU, HAS TRACKED SOUTHWESTWARD AT 20 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH PERSISTENT DEEP CONVECTION IN THE SOUTHERN SEMI-CIRCLE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EXTRAPOLATION FROM A 091410Z 37 GHZ SSMIS MICROWAVE IMAGE AND 091638Z METOP-B ASCAT IMAGE. THE AFOREMENTIONED MICROWAVE IMAGE DEPICTS THAT THE DEEP CONVECTION IS LOCATED IN THE SOUTHERN SEMICIRCLE AND IS SHEARED SLIGHTLY FROM THE LLCC. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS WHICH IS BASED ON A DVORAK CURRENT INTENSITY ESTIMATE OF T4.0 (65 KNOTS) FROM PGTW AND IS HEDGED BELOW A RECENT SATCON ESTIMATE OF. ENVIRONMENTAL ANALYSIS REVEALS THAT THE SYSTEM IS IN AN AREA OF MODERATE TO HIGH (15-20 KNOTS) VERTICAL WIND SHEAR AND IS TRACKING THROUGH AN AREA OF WARM (26-27 CELSIUS) SEA SURFACE TEMPERATURES. UPPER LEVEL ANALYSIS SHOWS THAT THE SYSTEM HAS A STRONG POLEWARD OUTFLOW CHANNEL.TC 04S IS TRACKING WEST-SOUTHWESTWARD ALONG THE WESTERN EXTENT OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) LOCATED TO THE EAST. THE SYSTEM WILL CONTINUE TO TRACK SOUTH-SOUTHWEST THROUGH TAU 12, AFTER WHICH THE TRACK WILL SHIFT MORE SOUTHERLY AS TC 04S ROUNDS THE RIDGE AXIS AND BEGINS TO ACCELERATE TO THE SOUTHEAST. THE SYSTEM HAS BEGUN A WEAKENING TREND DUE TO A MARGINALLY FAVORABLE ENVIRONMENT. AFTER TAU 24, THE SYSTEM WILL BEGIN TO INTERACT WITH AN APPROACHING TOUGH WHICH WILL INTRODUCE HIGHER VERTICAL WIND SHEAR WHICH, COMBINED WITH COOLER SEA SURFACE TEMPERATURES WILL CONTINUE THE WEAKENING TREND. TC IRVING IS FORECAST TO BEGIN EXTRA TROPICAL TRANSITION BY TAU 36 AND COMPLETE THE TRANSITION BY TAU 48. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT WITH JGSM BEING THE PRINCIPLE WESTWARD OUTLIER, SHOWING A SLIGHTLY WIDER TURN TO THE SOUTHEAST THAN THE REMAINING CONSENSUS MEMBERS. DESPITE THESE TWO OUTLIERS THE OVERALL AGREEMENT OF THE REMAINING OUTLIERS LENDS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 091800Z IS 24 FEET. NEXT WARNINGS AT 100300Z, 100900Z, 101500Z AND 102100Z. REFER TO TROPICAL CYCLONE 03S (AVA) WARNINGS (WTXS31 PGTW) FOR SIX-HOURLY UPDATES. REFER TO TROPICAL CYCLONE 05S (FIVE) WARNINGS (WTXS33 PGTW)FOR SIX-HOURLY UPDATES.//