Tropical Storm CHOI-WAN Advisory 05 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (CHOI-WAN) WARNING
NR 10//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 23W (CHOI-WAN), LOCATED APPROXIMATELY 794 NM
NORTHEAST OF ANDERSEN AFB, GUAM HAS TRACKED WEST-NORTHWESTWARD AT 13
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY (EIR) CONTINUES TO SHOW DEEPENED CURVED CONVECTION ALONG THE
WESTERN PERIPHERY THAT HAS BUILT CLOSER TO THE CENTER OF THE
CENTROID. A 041619Z AMSU-B MICROWAVE IMAGE REVEALS CONVECTIVE BANDS
WRAPPING INTO A LARGE LOW LEVEL CIRCULATION CENTER (LLCC). THE
CURRENT POSITION IS BASED ON THE EIR LOOP AND SATELLITE FIXES FROM
PGTW AND RJTD WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 55
KNOTS IS BASED ON IMPROVING STRUCTURE AND A RECENT SATCON INTENSITY
ESTIMATE OF 54 KNOTS. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT WITH A POINT SOURCE PROVIDING RADIAL OUTFLOW AND LOW
VERTICAL WIND SHEAR (VWS). ADDITIONALLY, WARM SEA SURFACE
TEMPERATURES (SSTS) ARE CONDUCIVE FOR FURTHER DEVELOPMENT. TS 23W IS
TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUB-TROPICAL
RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
   B. TS 23W WILL CONTINUE TRACKING WESTWARD UNDER THE INFLUENCE OF
THE STR OVER THE NEXT 24 HOURS. AFTERWARDS, TS CHOI-WAN IS FORECAST
TO ROUND THE STR AND TRACK MORE POLEWARD. FAVORABLE ENVIRONMENTAL
CONDITIONS WILL PERSIST OVER THE NEXT 48 HOURS; HOWEVER, DUE TO THE
BROAD NATURE OF THE SYSTEM, TS 23W IS EXPECTED TO GRADUALLY
INTENSIFY AS IT CONTINUES TO CONSOLIDATE. AS THE SYSTEM GAINS
LATITUDE, IT WILL ENCOUNTER INCREASING VWS AND DECREASING SSTS WHICH
WILL BEGIN TO WEAKEN THE SYSTEM.
   C. CONTINUED UNFAVORABLE CONDITIONS WILL FURTHER DECAY THE
SYSTEM. BY TAU 72,  TS CHOI-WAN WILL BEGIN EXTRA-TROPICAL TRANSITION
AS IT INTERACTS WITH MIDLATITUDE WESTERLIES. TS 23W WILL BE FULLY
EMBEDDED IN THE BAROCLINIC ZONE, GAINING FRONTAL CHARACTERISTICS,
AND TRANSITIONING TO A STRONG COLD-CORE LOW BY THE END OF THE
FORECAST PERIOD. AVAILABLE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT;
HOWEVER, GIVEN THE UNCERTAINTY IN THE INITIAL POSITION AND THE
CURRENT STORM MOTION, THE JTWC FORECAST TRACK CONFIDENCE LEVEL
REMAINS LOW.//
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