WDPN32 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (TALIM) WARNING NR 
03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 06W (TALIM), LOCATED APPROXIMATELY 210 NM 
SOUTH-SOUTHWEST OF HONG KONG, HAS TRACKED NORTH-NORTHEASTWARD AT 04 
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) SHOWS DEEP CONVECTION OVER THE LOW-LEVEL CIRCULATION 
CENTER (LLCC), WHICH HAS BECOME EMBEDDED INSIDE THIS CONVECTION 
WITHIN THE PAST SIX HOURS. THE INITIAL POSITION IS BASED ON THE MSI 
IMAGERY AND A FIX FROM PGTW WITH LOW CONFIDENCE. THE CURRENT 
INTENSITY OF 45 KNOTS IS BASED ON A 2.5/2.5 DVORAK ESTIMATE FROM 
PGTW AND A 0147 ASCAT PASS SHOWING FORTY KNOTS ON THE SOUTHERN 
PERIPHERY OF THE STORM. UPPER-LEVEL ANALYSIS INDICATES WEAK RIDGING 
HAS BUILT IN OVER THE LLCC, WITH MODERATE VERTICAL WIND SHEAR (VWS) 
(15-20 KNOTS). THIS WEAK RIDGE AND MODERATE VWS ARE PROVIDING GOOD 
EQUATORWARD FLOW AND THE SUBTROPICAL RIDGE (STR) THAT IS BUILT IN 
OVER SOUTHERN CHINA IS SHUTTING OFF ANY POLEWARD FLOW. THE SYSTEM 
HAS BEEN TRACKING WITHIN THE LOW- TO MID-LEVEL GRADIENT FLOW TO THE 
NORTHEAST. AS TY 05W (GUCHOL) CONTINUES TO EXIT THE AREA, THE STR 
SHOULD BUILD BACK IN TO BECOME THE DOMINANT STEERING FACTOR. SEA 
SURFACE TEMPERATURES (SSTS) THROUGHOUT THE SOUTH CHINA SEA (SCS) 
ARE FAVORABLE FOR FURTHER DEVELOPMENT. 
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 06W IS EXPECTED TO SLOWLY TRACK NORTHEASTWARD OVER THE 
NEXT 24 HOURS WITHIN THE GRADIENT FLOW AS THE STR BEGINS TO BUILD. 
THROUGH TAU 48, TS 06W WILL INTENSIFY UNDER FAVORABLE UPPER-LEVEL 
SUPPORT AND WARM SSTS. TS 06W WILL TRACK OVER THE TAIWAN STRAIT 
AROUND TAU 60 WHICH SHOULD CAUSE THE SYSTEM TO BEGIN TO WEAKEN DUE 
TO LAND INTERACTION AND LOWER SSTS. AS THE SYSTEM EXITS THE TAIWAN 
STRAIT IT WILL STILL BE OF SIGNIFICANT STRENGTH BUT WILL BE IN AN 
ENVIRONMENT OF POOR SSTS AND STRONG VWS. WARM SSTS NEAR THE RYUKYU 
ISLANDS IS WELL EAST OF THE TRACK AND WILL NOT FAVOR FURTHER 
DEVELOPMENT THROUGH TAU 72. CONFIDENCE REMAINS LOW WITH THE 
FORECAST AS IT RELIES HEAVILY ON THE TIMING AND THE DEVELOPMENT OF 
THE STR.
   C. IN THE EXTENDED FORECAST, TS 06W WILL CONTINUE TO TRACK ALONG 
THE NORTHWESTERN PERIPHERY OF THE RE-BUILDING STR TOWARDS 
SOUTHWESTERN KYUSHU. DECREASING SSTS (22 TO 26 CELSIUS) AND 
INCREASING VWS WILL NOT ALLOW FOR FURTHER DEVELOPMENT. AS TS TALIM 
MAKES APPROACH TO THE SOUTHERN TIP OF KYUSHU, NEAR TAU 96, IT WILL 
UNDER GO EXTRA-TROPICAL TRANSITION (ETT) WHICH WILL BE COMPLETE BY 
TAU 120. CONFIDENCE REMAINS LOW FOR THE EXTENDED TAUS BASED ON THE 
TIMING OF THE STEERING STR DEVELOPMENT. MODEL GUIDANCE IS IN GOOD 
AGREEMENT WITH THE FORECAST TRACK; HOWEVER, THE TIMING OF THE RE-
DEVELOPMENT OF THE STR VARIES WHICH IS VARYING THE TIMING OF THE 
SYSTEMS TRACK SPEEDS. THIS FORECAST IS BASED PREDOMINANTLY ON THE 
CONSENSUS OF AVAILABLE MODEL GUIDANCE.//
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