Tropical Storm VICENTE Advisory Sun Jul 22

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (VICENTE) WARNING
NR 06//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 09W (VICENTE), LOCATED APPROXIMATELY 180 NM SOUTH-
SOUTHEAST OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS CONTINUED DEVELOPMENT OF DEEP CONVECTIVE BANDING WRAPPING
ALONG THE SOUTHERN AND WESTERN SECTORS. THE CURRENT POSITION IS
BASED ON A 212250Z WINDSAT CORIOLIS 37 GHZ IMAGE WITH HIGH
CONFIDENCE. THE CURRENT INTENSITY IS MAINTAINED HIGHER THAN THE
SUBJECTIVE DVORAK ESTIMATES OF 25-35 KNOTS FROM PGTW, RJTD, AND
KNES DUE TO THE OBJECTIVE 211900Z SATCON ESTIMATE OF 42 KNOTS AND
DEEP CONVECTIVE SPIRAL BAND CURVATURE OVER THE WESTERN SEMI-CIRCLE
OF THE LLCC. UPPER-LEVEL ANALYSIS CONTINUES TO SHOW A SMALL
ANTICYCLONE BUILDING JUST NORTH THE LLCC, SUPPORTING THE EQUATORIAL
VENTING OF THE SYSTEM. HOWEVER, INDUCED UPPER-LEVEL TROUGHING
EXISTS BETWEEN THIS SMALLER ANTICYCLONE AND A POINT SOURCE OF
DIVERGENCE TO THE SOUTHEAST OF THE SYSTEM WHICH IS INDUCING UPPER-
LEVEL CONVERGENCE EAST OF THE LLCC. TS 09W IS CURRENTLY BEING
STEERED BY THE SOUTHERN PERIPHERY OF A ZONAL DEEP-LAYERED
SUBTROPICAL RIDGE (STR) ANCHORED OVER EASTERN ASIA AND IS UNDER
MODERATE 15-20 KNOT EASTERLY VWS.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS VICENTE WILL CONTINUE TO TRACK WEST-NORTHWESTWARDS UNDER
THE SOUTHERN PERIPHERY THE STEERING STR FOR THE ENTIRE FORECAST
PERIOD. THE RECENT WEST-NORTHWESTWARDS MOTION IS DUE TO THE
INCREASED INTENSITY OF TS 09W WHICH ALLOWS THE SYSTEM TO SLIGHTLY
WEAKEN THE RIDGE PERIPHERY VIA BETA-EFFECT PROPAGATION. TS 09W
SHOULD CONTINUE TO GRADUALLY INTENSIFY AS UPPER-LEVEL CONDITIONS
SHOULD REMAIN CONSISTENT, IF NOT BECOME SLIGHTLY BETTER, DURING THE
NEXT 36-48 HOURS. BY TAU 48 THE LLCC WILL ENCOUNTER COMPETING
INFLUENCES FROM LAND INTERACTION WITH THE COASTLINE WEST OF THE
LUICHOW PENINSULA AND WARM SST (28-30 CELSIUS) IN THE GULF OF
TONKIN BUT SHOULD BE ABLE TO MAINTAIN STRONG TS STRENGTH AS IT
APPROACHES NORTHERN VIETNAM BY TAU 72.
   C. TS 09W SHOULD DISSIPATE OVERLAND BY TAU 96. NUMERICAL MODEL
GUIDANCE REMAINS IN GOOD AGREEMENT IN REGARDS TO THE TRACK
TRAJECTORY BUT THE NOGAPS, GFDN, JGSM, AND WBAR SEEM TOO SLOW IN
TRACK SPEED FOR THE SYNOPTIC ENVIRONMENT. DESPITE THESE TRANSLATION
SPEED DISCREPANCIES, HIGH CONFIDENCE REMAINS IN THE OFFICIAL JTWC
TRACK FORECAST DUE TO THE WELL ESTABLISHED SYNOPTIC ENVIRONMENT AS
ANALYZED FROM THE 211200Z UPPER-LEVEL SOUNDINGS IN THE AREA.//
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