WDPN31 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (SAUDEL) WARNING NR 
026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS. 
   TROPICAL STORM (TS) 19W (SAUDEL), LOCATED APPROXIMATELY 90 NM 
NORTH OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS (KTS) 
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY 
(MSI) REVEALS A FULLY-EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION 
CENTER (LLCC). THE PREVIOUS SHEARED DEEP CONVECTION HAS 
SIGNIFICANTLY DISSIPATED OVER THE PAST SIX HOURS. A TIMELY 250559Z 
AMSR2 89 GHZ MICROWAVE IMAGE DEPICTS DEFINED BANDING WRAPPING INTO 
THE LLCC, WHICH IN CONJUNCTION WITH THE MSI PLACES HIGH CONFIDENCE 
IN THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 40 KTS 
BASED ON A 250100Z ASCAT-A PASS SHOWING A SWATH OF 35-40 KT WINDS IN 
THE NORTHWEST QUADRANT. ADDITIONALLY, THE INTENSITY IS SUPPORTED 
WITH GOOD CONFIDENCE BY DVORAK CURRENT INTENSITY ESTIMATES OF T2.5-
3.0 (35-45 KTS) BY PGTW AND RJTD. ENVIRONMENTAL ANALYSIS INDICATES A 
MARGINAL ENVIRONMENT WITH MODERATE (15-20 KTS) VERTICAL WIND SHEAR, 
FAIR EQUATORWARD OUTFLOW AND MARGINAL (26-27 CELSIUS) SEA SURFACE 
TEMPERATURE VALUES. 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. TS 19W WILL CONTINUE TO TRACK WESTWARD THEN WEST-SOUTHWESTWARD 
THROUGH THE FORECAST PERIOD, STEADILY WEAKENING AS IT APPROACHES THE 
COAST. AFTER MAKING LANDFALL NEAR TAU 12, THE SYSTEM WILL RAPIDLY 
WEAKEN AS IT TRANSITS ACROSS MOUNTAINOUS TERRAIN WITH DISSIPATION 
EXPECTED BY TAU 24. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD 
AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST 
TRACK WHICH LIES NEAR THE MULTI-MODEL CONSENSUS.//
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