WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (SAUDEL) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS. 
   TYPHOON 19W (SAUDEL), LOCATED APPROXIMATELY 270 NM SOUTH OF HONG 
KONG, HAS TRACKED WESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. 
ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS TIGHTLY CURVED 
BANDING WRAPPING INTO A PARTIALLY EXPOSED LOW LEVEL CIRCULATION 
CENTER (LLCC), WITH DEEP CONVECTION DISPLACED TO THE NORTHWEST UNDER 
MODERATE (15-20 KNOT) VERTICAL WIND SHEAR (VWS). THE CURRENT 
POSITION IS BASED ON THE PGTW FIX AND SUPPORTED BY A 232241Z SSMIS 
37 GHZ PARTIAL PASS WITH AN ILL DEFINED CENTER. THE INTENSITY IS 
LOWERED TO 55 KNOTS, WHICH IS ON THE LOW END OF SUBJECTIVE DVORAK 
FIXES ACCOUNTING FOR 50-55 KNOT SATCON AND 45 KNOT ADT ESTIMATES 
WHICH REFLECT A STRONG WEAKENING TREND DUE TO THE EFFECTS OF THE 
VWS. TY 19W IS TRACKING STEADILY WESTWARD AS SUB-TROPICAL RIDGING 
(STR) TO THE NORTH IS BUILDING.  WARM SEA SURFACE TEMPERATURES (28-
29C) REMAINS IN PLACE, BUT UPPER LEVEL OUTFLOW HAS DEGRADED, FURTHER 
ADDING TO THE WEAKENING TREND. 
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 19W WILL CONTINUE TO MOVE STEADILY WESTWARD TO WEST-
SOUTHWESTWARD UNDER THE CONTINUOUS STEERING INFLUENCE OF THE STR 
THROUGHOUT THE FORECAST PERIOD. STEADY WEAKENING SHOULD PERSISTENT 
AS NORTHEASTERLY VERTICAL WIND SHEAR CONTINUES TO IMPACT THE SYSTEM. 
LANDFALL OVER CENTRAL VIETNAM IS EXPECTED AFTER TAU 36, WITH 
DISSIPATION OVER LAND EXPECTED BY TAU 48. NUMERICAL MODEL GUIDANCE 
REMAINS IN GOOD AGREEMENT WITH THE OVERALL FORECAST SCENARIO, AND 
THE MODEL TRACK FORECAST CONSENSUS HAS BEEN STEADY FOR THE PAST 
SEVERAL RUNS. THEREFORE, THERE IS HIGH CONFIDENCE IN THE CURRENT 
JTWC TRACK FORECAST.
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