WDPN31 PGTW 100300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 30// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 313 NM SOUTH- SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTH- NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A 25 NM CLOUD-FILLED EYE WITH THINNING CONVECTION OVER THE NORTHERN PERIPHERY AND WESTERN SEMI-CIRCLE. THE CURRENT POSITION IS BASED ON THE EYE FEATURE ON THE MSI WITH HIGH CONFIDENCE. THE INITIAL INTENSITY HAS DECREASED TO 125 KNOTS BASED ON AN OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES AND THE CURRENT STRUCTURE. UPPER-LEVEL ANALYSIS CONTINUES TO INDICATE FAVORABLE VERTICAL WIND SHEAR (VWS) AND EXCELLENT OUTFLOW THAT IS SUSTAINING THE CONVECTION. TY 19W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF AN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 19W WILL CONTINUE TRACKING NORTHWARD OVER NEXT 24 HOURS AS IT ROUNDS THE WESTERN EDGE OF THE STEERING STR. BETWEEN TAU 24 AND 36, A MIGRATORY SHORTWAVE RIDGE PASSING FROM THE NORTHWEST WILL MOMENTARILY DEFLECT TY 19W NORTH-NORTHWESTWARD. BY TAU 48, A MID-LATITUDE TROUGH PASSING OVER THE KOREA PENINSULA WILL WEAKEN THE PRIMARY STEERING STR AND CAUSE THE CYCLONE TO RECURVE NORTH- NORTHEASTWARD. CONCURRENTLY, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT ACCELERATES NORTHEASTWARD ALONG SOUTHERN JAPAN. INCREASING VWS ASSOCIATED WITH THE MID-LATITUDE WESTERLIES WILL WEAKEN THE SYSTEM TO 70 KNOTS BY TAU 72. C. IN THE EXTENDED TAUS, CONTINUED INTERACTION WITH THE MIDLATITUDE WESTERLIES WILL RAPID WEAKEN TY 19W FOR THE REMAINDER OF THE FORECAST PERIOD. BY TAU 96, TY VONGFONG IS EXPECTED TO COMPLETE ETT AS IT BECOMES A GALE FORCE COLD-CORE LOW OVER NORTHERN JAPAN. AVAILABLE MODEL GUIDANCE IS OVERALL IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO JTWC TRACK FORECAST THAT IS POSITIONED CLOSE TO AND SLIGHTLY FASTER THAN THE MULTI-MODEL CONSENSUS.//NNNN No Public Storm Warning Signal Estimated rainfall amount is from 7.5 – 25 mm per hour (heavy – intense) within the 700 km diameter of the typhoon. OMPONG is not expected to make landfall to any part of the country. However, it is enhancing the northeasterly winds resulting to rough to very rough sea conditions over the northern and western seaboards of Northern Luzon and over the eastern seaboard of Luzon and of Visayas. Fisherfolks and those using small seacrafts are advised not to venture out over the said seaboards.
Posted on: Fri, 10 Oct 2014 03:06:10 +0000
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