Tropical Storm NAKRI Advisory Sáb, 09-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (NAKRI) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 25W (NAKRI), LOCATED APPROXIMATELY 442 NM EAST-NORTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH THE MAJORITY OF THE CONVECTION OFFSET TO THE SOUTHWEST. ADDITIONALLY, A 090556Z ATMS 88GHZ MHZ MICROWAVE IMAGE DEPICTS CONVECTIVE BANDING WRAPPING INTO A PARTIAL MICROWAVE EYE FEATURE, PLACING GOOD CONFIDENCE IN THE INITIAL POSITION. BASED ON A 090555Z SATCON ESTIMATE OF 63 KTS AND A PGTW DVORAK CURRENT INTENSITY OF T3.5 (55 KNOTS), THE INTENSITY IS ASSESSED AT 60 KTS. THE SYSTEM IS POSITIONED WITHIN A MODERATELY UNFAVORABLE ENVIRONMENT WITH FAIR DIFFLUENCE OFFSET TO THE SOUTHWEST, MODERATE-HIGH (20-25 KTS) VERTICAL WIND SHEAR (VWS) AND WARM (28-29 DEGREES CELSIUS) SEA SURFACE TEMPERATURES (SST). TS 25W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE NORTH WHICH IS BUILDING EASTWARD FROM MAINLAND SOUTHEAST ASIA.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 25W WILL MAINTAIN A GENERALLY WEST-NORTHWESTWARD TRACK THROUGH TAU 72 ALONG THE SOUTHERN PERIPHERY OF THE AFOREMENTIONED STR TO THE NORTH. MODERATE VWS AND FAIR UPPER-LEVEL OUTFLOW ARE EXPECTED TO HAMPER ANY FURTHER DEVELOPMENT AND IS EXPECTED TO BEGIN SLOWLY WEAKENING AT TAU 24. OVERALL, NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE WEST-NORTHWARD TRACK. HOWEVER, THERE IS SOME ALONG-TRACK SPREAD AFTER TAU 36 AS TS 25W MAKES LANDFALL IN VIETNAM. TS 25W IS EXPECTED TO RAPIDLY WEAKEN AS IT MOVES OVER LAND AND ENCOUNTERS RUGGED TERRAIN WITH THE SYSTEM DISSIPATING AROUND TAU 72. THE CURRENT JTWC FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS, WITH FAIR CONFIDENCE.//
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