WTXS31 PGTW 180300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 10S (JOSHUA) WARNING NR 006// RMKS/ 1. TROPICAL CYCLONE 10S (JOSHUA) WARNING NR 006 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 180000Z --- NEAR 19.7S 87.9E MOVEMENT PAST SIX HOURS - 235 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT REPEAT POSIT: 19.7S 87.9E --- FORECASTS: 12 HRS, VALID AT: 181200Z --- 20.0S 86.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 265 DEG/ 10 KTS --- 24 HRS, VALID AT: 190000Z --- 20.1S 84.1E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 265 DEG/ 10 KTS --- 36 HRS, VALID AT: 191200Z --- 20.3S 81.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 255 DEG/ 11 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 200000Z --- 20.9S 79.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 180300Z POSITION NEAR 19.8S 87.5E. 18JAN21. TROPICAL CYCLONE 10S (JOSHUA), LOCATED APPROXIMATELY 1160 NM EAST-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT CONVECTION HAS STARTED FLARING AGAIN NEAR THE LLCC AS THE SYSTEM MOVED THROUGH THE DIURNAL CONVECTIVE MAXIMUM. TRANSVERSE BANDING IN THE WEST AND SOUTHERN QUADRANTS WOULD ARGUE FOR IMPROVED POLEWARD OUTFLOW AS WELL. WHILE THE LLCC WAS OBSCURED AT THE 180000Z HOUR, EXTRAPOLATION OF A LOW EMISSIVITY REGION AND WELL- DEFINED LOW-LEVEL BANDS EVIDENT IN A 172238Z SSMIS 91GHZ MICROWAVE IMAGE, LEND MODERATE CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS ASSESSED AT 40 KNOTS WITH MODERATE CONFIDENCE BASED ON AN AVERAGE OF MULTI-AGENCY DVORAK INTENSITY FIXES OF T2.5-3.0 (35- 45 KTS) FROM PGTW AND FMEE AND AN ADT ESTIMATE OF T3.4. TC 10S IS FORECAST TO CONTINUE TRACKING WEST-SOUTHWESTWARD ALONG THE NORTHERN FLANK OF LOW TO MID-LEVEL STR LOCATED TO THE SOUTH THROUGH TAU 24, WITH A SLIGHT TURN POLEWARD AFTER THIS POINT TOWARDS A DEVELOPING WEAKNESS IN THE STEERING RIDGE. WITH THE EXCEPTION OF NAVGEM, WHICH HAS CONSISTENTLY TRACKED THE SYSTEM ON A MORE SOUTHWESTWARD TRACK, NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 50NM SPREAD AT TAU 48. TC 10S IS FORECAST TO MAINTAIN INTENSITY FOR THE NEXT 12 HOURS UNDER MARGINALLY SUPPORTIVE CONDITIONS BUT WILL WEAKEN STEADILY DUE TO INCREASING VWS, CONVERGENT FLOW ALOFT AND DRY AIR ENTRAINMENT, DISSIPATING AS A TROPICAL CYCLONE OVER WATER BY TAU 48. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 180000Z IS 15 FEET. NEXT WARNINGS AT 181500Z AND 190300Z. REFER TO TROPICAL CYCLONE 12S (ELOISE) WARNINGS (WTXS32 PGTW)FOR TWELVE-HOURLY UPDATES.// NNNN