WDPN31 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (SAUDEL) WARNING NR 
023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS. 
   TROPICAL STORM (TS) 19W (SAUDEL), LOCATED APPROXIMATELY 207 NM 
EAST-NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS 
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY REVEALS DEEP FLARING CONVECTION OVERHEAD THE LOW LEVEL 
CIRCULATION CENTER (LLCC). A BULLSEYE 241229Z ASCAT-A DEPICTS A 
SMALL SWATH OF 45-50 KTS WIND BARBS TO THE SOUTHWEST OF A SYMMETRIC 
LLCC AND WEAKER WINDS ELSEWHERE, LENDING GOOD CONFIDENCE TO THE 
INITIAL POSITION AND INTENSITY. THE INITIAL INTENSITY REMAINS AT 50 
KTS, HEDGED SLIGHTLY UNDER MULTI-AGENCY DVORAK CURRENT INTENSITY 
ESTIMATES OF T3.5 (55 KTS) BASED ON THE ASCAT DATA. ENVIRONMENTAL 
ANALYSIS SHOWS MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), GOOD 
EQUATORWARD OUTFLOW AND WARM (27-28 CELSIUS) SEA SURFACE 
TEMPERATURES (SST) CONTRIBUTING TO AN OVERALL MARGINAL ENVIRONMENT. 
TS 19W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF A 
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. 
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED RIDGE, TS 
19W WILL CONTINUE TO MOVE STEADILY WESTWARD THEN WEST-SOUTHWESTWARD 
THROUGHOUT THE FORECAST PERIOD. INCREASING VWS WILL CAUSE THE SYSTEM 
TO SLOWLY WEAKEN AS IT APPROACHES VIETNAM WITH LANDFALL ANTICIPATED 
PRIOR TO TAU 36. AFTERWARDS, THE SYSTEM WILL RAPIDLY WEAKEN AS IT 
TRANSITS ACROSS THE RUGGED TERRAIN WITH DISSIPATION EXPECTED BY TAU 
48. NUMERICAL MODEL GUIDANCE REMAINS IN EXCELLENT AGREEMENT WITH A 
SPREAD OF ONLY 54 NM PRIOR TO LANDFALL. OVERALL, THERE IS HIGH 
CONFIDENCE IN THE JTWC FORECAST TRACK WHICH LIES NEAR THE MULTI-
MODEL CONSENSUS.//
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