TC 26P : crossing Northern Vanuatu and peaking within 24hours, 18/15utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 26P.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A MEDIUM SIZED SYSTEM WITH DISORGANIZED DEEP FLARING CENTRAL CONVECTION THAT IS SHEARED FROM AN EXPOSED LOW LEVEL CIRCULATION (LLC). HOWEVER, A FRESH BALL OF CONVECTION DUE SOUTH OF THE THE LLC HAS BEGUN TO GROW AND EXPAND INTO THE LLC OVER THE LAST FEW HOURS. THE MAIN FORMATIVE RAIN BAND IS FEEDING IN FROM THE NORTHEAST. THE EIR LOOP ALSO SHOWS TRANSVERSE BANDING ALONG THE SOUTHERN PERIPHERY, AN INDICATION OF STRONG VERTICAL WIND SHEAR. THE INITIAL POSITION AND INTENSITY ARE EXTRAPOLATED WITH HIGH CONFIDENCE FROM THE 181052Z ASCAT BULLSEYE PASS WITH THE STRONGEST WIND BARBS ALONG THE SOUTHWEST QUADRANT UNDER THE FLARING CONVECTION.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 26P IS EXPECTED TO CONTINUE SOUTHWESTWARD ALONG THE NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE (STR) AND TRACK OVER THE NORTHERN ISLANDS OF VANUATU OVER THE NEXT 24HRS. AFTER 72H, IT WILL ROUND THE STR AXIS AND RECURVE SOUTHEASTWARD TOWARD NEW CALEDONIA. THE MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL WEAK INTENSIFICATION TO 40KTS AT 12/36H. AFTERWARD, INCREASING VERTICAL WIND SHEAR (VWS) WILL GRADUALLY ERODE THE SYSTEM TO DISSIPATION BY 96H, POSSIBLY SOONER.

181052Z ASCAT BULLSEYE PASS WITH THE STRONGEST WIND BARBS ALONG THE SOUTHWEST QUADRANT UNDER THE FLARING CONVECTION.

MODEL DISCUSSION: NUMERICAL MODELS WIDELY SPREAD OUT TO OVER 575KM BY 96H BUT ARE IN BROAD AGREEMENT WITH THE POLEWARD AND RECURVING TRACK WITH AFUM ON THE RIGHT AND NAVGEM ON THE LEFT MARGIN OF THE MODEL ENVELOPE. IN VIEW OF THIS, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS.