Tropical Storm VONGFONG Advisory Fri May 15

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 01W (VONGFONG) WARNING
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 01W (VONGFONG), LOCATED APPROXIMATELY 289 NM EAST-
SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 09 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL VISIBLE SATELLITE
IMAGERY SHOWS A TIGHT CLOUD FILLED 8NM EYE. TY 01W IS CURRENTLY
LOCATED OVER EASTERN SAMAR. A 140531Z GMI 89GHZ MICROWAVE PASS
REVEALED A LARGE SWATH OF DEEP CONVECTION AROUND THE EASTERN SEMI-
CIRCLE, WHILE THE CORE CONVECTION ALONG THE WESTERN SIDE OF THE
MICROWAVE EYE WAS DEGRADED. THE INITIAL INTENSITY IS SET AT 100
KNOTS BASED ON A T5.5 (102 KNOTS) FROM RJTD AND A 140459Z SATCON
ESTIMATE OF 103 KNOTS. THE INITIAL POSITION WAS PLACED WITH HIGH
CONFIDENCE BASED ON EYE FIXES AND THE AFOREMENTIONED MICROWAVE
IMAGE. THE ENVIRONMENT REMAINS FAVORABLE WITH ROBUST RADIAL OUTFLOW
AND WARM SSTS PARTIALLY OFFSETTING MID-LEVEL DRY AIR. TY 01W IS
BEING STEERED BY A DEEP-LAYER SUBTROPICAL RIDGE (STR) POSITIONED
NORTHEAST OF LUZON WHICH IS EXTENDING WEST TOWARD THE LUZON STRAIT.
3. FORECAST REASONING.
   A. THERE HAS BEEN NO SIGNIFICANT CHANGE TO THE FORECAST
PHILOSOPHY.
   B. TY 01W IS EXPECTED TO GRADUALLY SHIFT TO A NORTHWEST AND THEN
NORTHWARD TRACK OVER THE NEXT 12-36 HOURS AS IT ROUNDS THE
AFOREMENTIONED STR. THE TRACK FOLLOWS ALONGSIDE THE MULTI-MODEL
CONSENSUS SOLUTION. AFTER TAU 48, TY 01W SHOULD COMPLETE ROUNDING
THE STR AXIS. A CONTINUOUS WEAKENING TREND IS FORECAST AS TY 01W
TRAVELS OVER ACROSS THE PHILIPPINES AS FAVORABLE CONDITIONS OFFSET
THE FRICTIONAL EFFECTS OF THE ISLANDS. A MORE PRONOUNCED WEAKENING
TREND IS EXPECTED AS THE SYSTEM TRACKS OVER LUZON. DUE TO
UNCERTAINTY OF WHEN THE NORTHWARD TURN WILL OCCUR, OVERALL
CONFIDENCE IS FAIR FOR THIS PORTION OF THE FORECAST WITH A CROSS
TRACK SPREAD OF 140NM AT TAU 48.
   C. AFTER TAU 72, TY 01W WILL COMPLETE RECURVATURE AND BEGIN A
NORTHEASTWARD TRACK AFTER ENTERING THE LUZON STRAIT. INCREASING VWS
(25-30 KNOTS) AS TY 01W NEARS A BAROCLINIC ZONE, ALONG WITH COOLING
SSTS WILL LEAD TO FURTHER WEAKENING OF THE SYSTEM TO 35 KTS BY TAU
96. AT TAU 72, INTERACTION WITH STRONG UPPER LEVEL WESTERLY FLOW
WILL CAUSE THE SYSTEM TO BEGIN EXTRATROPICAL TRANSITION, WITH
COMPLETE EXTRATROPICAL TRANSITION COMPLETE BY TAU 120 AS IT IS FULLY
ABSORBED INTO THE BAROCLINIC ZONE. THERE IS SIGNIFICANT ALONG TRACK
SPREAD OF MODEL SOLUTIONS AFTER TAU 72. THE LARGE SPREAD IN MODEL
GUIDANCE LENDS HIGH UNCERTAINTY DURING THIS PERIOD AND THUS
LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.//
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