WDPN31 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (SAUDEL) WARNING NR 
022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS. 
   TROPICAL STORM (TS) 19W (SAUDEL), LOCATED APPROXIMATELY 262 NM 
EAST-NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS 
(KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY REVEALS A PARTIALLY-EXPOSED LOW LEVEL CIRCULATION CENTER 
(LLCC) WITH FLARING DEEP CONVECTION OVERHEAD AND OVER THE WESTERN 
SEMICIRCLE. BASED ON THE PARTIALLY EXPOSED NATURE, THERE IS GOOD 
CONFIDENCE IN THE INITIAL POSITION WHICH IS IN GOOD AGREEMENT WITH 
THE PGTW AND RJTD FIXES. THE INITIAL INTENSITY IS ASSESSED AT 50 KTS 
BASED ON A 240235Z METOP-B ASCAT IMAGE DEPICTING SWATHS OF 45-50 KT 
WINDS TO THE NORTHEAST AND SOUTHWEST. A 240233Z SATCON INTENSITY 
ESTIMATE OF 47 KTS LENDS GOOD SUPPORT TO THE INITIAL INTENSITY. 
ENVIRONMENTAL ANALYSIS REVEALS TS 19W IS EXPERIENCING MODERATE (15-
20 KTS) VERTICAL WIND SHEAR (VWS), GOOD EQUATORWARD OUTFLOW, AND 
WARM (27-28 CELSIUS) SEA SURFACE TEMPERATURES (SST). TS 19W IS 
TRACKING STEADILY WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE 
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. TS 19W WILL CONTINUE TO MOVE STEADILY WESTWARD THEN WEST-
SOUTHWESTWARD THROUGHOUT THE FORECAST PERIOD UNDER THE CONTINUOUS 
STEERING INFLUENCE OF THE STR, STEADILY WEAKENING DUE TO PERSISTENT 
EASTERLY VERTICAL WIND SHEAR IMPACTING THE SYSTEM. TS 19W SHOULD 
MAKE LANDFALL JUST AFTER TAU 36 WITH DISSIPATION OVER LAND 
ANTICIPATED BY TAU 48. NUMERICAL MODEL GUIDANCE IS IN EXCELLENT 
AGREEMENT WITH A SPREAD OF ONLY 50 NM AT TAU 36. OVERALL, THERE IS 
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK, LYING NEAR THE MULTI-
MODEL CONSENSUS.//
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