TC 14S(VERNON) subtropical//TC 18P(EVA): Final Warning//Invest 90B up-graded to Medium//Invest 96P, 04/06utc

JTWC ISSUED WARNING 5/FINAL ON TC 18P(EVA). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON SUBTROPICAL CYCLONE 14S(VERNON), TC 18P(EVA) AND INVEST 90B.

04/0415UTC.

REMARKS: 040300Z POSITION NEAR 25.4S 174.1E. 04MAR22. TROPICAL CYCLONE 18P (EVA), LOCATED APPROXIMATELY 900 KM EAST-SOUTHEAST OF NOUMEA, NEW CALEDONIA, HAS TRACKED NORTH- NORTHWESTWARD AT 17 KM/H OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS SHOWS A LARGE SYSTEM WITH ITS ASSOCIATED CONVECTION AND CIRRI CANOPY STRETCHED AND SHEARED EASTWARD, PARTLY EXPOSING THE LOW LEVEL CIRCULATION (LLC) AND STREAKS OF COLD-AIR STRATUS BANDS THAT ARE FEEDING INTO LLC. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTLY EXPOSED LLC IN THE MSI LOOP. THE INITIAL INTENSITY OF 35KTS IS BASED ON THE PGTW AND ADT DVORAK ESTIMATES OF T2.5/35KTS AND FROM RECENT ASCAT PASSES SHOWING 35KT BARBS ALONG THE SOUTHERN QUADRANTS AND 185+KM AWAY FROM THE CENTER. ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH STRONG EASTWARD OUTFLOW AND WARM SST OFFSET BY STRONG (30KT+) VWS AND THE INFLUX OF DRY AIR IN THE LOWER LEVELS, AS EVIDENCED BY THE COLD AIR STRATOCUMULUS BANDS IN THE MSI LOOP. A CYCLONE PHASE ANALYSIS ALSO INDICATES THAT TC 18P HAS TRANSITIONED INTO A SUBTROPICAL SYSTEM AND IS EXPECTED TO REMAIN AS SUCH AS IT SLOWLY TRACKS WESTWARD UNDER THE STEERING INFLUENCE OF A SHALLOW SUBTROPICAL RIDGE TO THE SOUTH. ADDITIONALLY, THE MARGINAL ENVIRONMENT WILL FURTHER DETERIORATE DUE TO INCREASING VWS AND PERSISTENT COLD DRY AIR INFLUX, LEADING TO DISSIPATION BY TAU 24, LIKELY SOONER. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI.

THE AREA OF CONVECTION (INVEST 90B) PREVIOUSLY LOCATED NEAR 4.8N 87.6E IS NOW LOCATED NEAR 7.6N 84.5E, APPROXIMATELY 770 KM SOUTHEAST OF CHENNAI, INDIA. ENHANCED INFRARED IMAGERY (EIR) AND A 031028Z SSMIS 91GHZ IMAGE DEPICT WEAK BANDS WRAPPING INTO A LOW LEVEL CIRCULATION (LLC). IN ADDITION, DEEP CONVECTION EXISTS WITHIN THE NORTHERN PERIPHERY OF THE SYSTEM. ENVIRONMENTAL ANALYSIS INDICATES MARGINAL CONDITIONS FOR TROPICAL CYCLONE DEVELOPMENT TO INCLUDE FAIR POLEWARD OUTFLOW, MODERATE (15-20KTS) VERTICAL WIND SHEAR, AND VERY WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL TRACK NORTHWESTWARD AND CONTINUE TO GRADUALLY INTENSIFY OVER THE NEXT 36-48HRS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.

GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL TRACK NORTHWESTWARD AND CONTINUE TO GRADUALLY INTENSIFY OVER THE NEXT 36-48HRS.

AN AREA OF CONVECTION (INVEST 96P) HAS PERSISTED NEAR 25.6S 172.5E, APPROXIMATELY 560 KM SOUTH-SOUTHEAST OF TONGA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A PARTIAL 040220Z GMI 89GHZ IMAGE DEPICT FORMATIVE BANDS WRAPPING INTO A LOW LEVEL CIRCULATION (LLC). THERE IS FLARING CONVECTION TO THE EASTERN PERIPHERY OF THE LLC. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR TROPICAL CYCLONE DEVELOPMENT TO INCLUDE ROBUST POLEWARD OUTFLOW, LOW (10-15KTS) VERTICAL WIND SHEAR, AND WARM (27- 28C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL CONSOLIDATE, CONTINUE TO TRACK SOUTHEASTWARD , AND GRADUALLY INTENSIFY OVER THE NEXT 48-72HRS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO LOW.

GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL CONSOLIDATE, CONTINUE TO TRACK SOUTHEASTWARD , AND GRADUALLY INTENSIFY OVER THE NEXT 48-72HRS.