WDPN31 PGTW 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (SAUDEL) WARNING NR 020//
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 ENHANCED INFRARED IMAGERY INDICATES THAT CONVECTION HAS 
BECOME INCREASINGLY MORE RAGGED AND DISORGANIZED OVER THE PAST SIX 
HOURS. THE CURRENT POSITION IS EXTRAPOLATED FROM RECENT ASCAT 
AMBIGUITIES AND NRCS DATA, AND IS SUPPORTED WITH FAIR CONFIDENCE BY 
A DEFINED CENTER IN A 231823Z AMSR2 36 GHZ PASS. THE LOW LEVEL 
CIRCULATION CENTER IS TRAILING BEHIND THE DEEP CONVECTION, WHICH IS 
PUSHING OFF FURTHER WEST DUE TO PERSISTENT 15-20 KNOT EASTERLY 
VERTICAL WIND SHEAR (VWS). THE INTENSITY IS LOWERED TO 65 KNOTS 
CONSIDERING THE PGTW DVORAK FINAL AND CURRENT INTENSITY ESTIMATES, 
AND ADJUSTING LOWER TO TAKE INTO ACCOUNT FALLING DATA-T VALUES AND 
55 TO 60 KNOT SATCON ESTIMATES. TY 19W IS TRACKING SLOWLY WESTWARD 
UNDER THE STEERING INFLUENCE OF WEAK RIDGING CONNECTING TWO 
SUBTROPICAL RIDGE CENTERS SITUATED TO THE WEST AND TO THE EAST OF 
THE SYSTEM. WARM SEA SURFACE TEMPERATURES (28-29C) AND MODERATE, 
WESTWARD UPPER-LEVEL OUTFLOW REMAIN IN PLACE, SLIGHTLY OFFSETTING 
THE EFFECTS OF THE VWS. 
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. SUBTROPICAL RIDGING IS EXPECTED TO BUILD TO THE NORTH OF TY 
19W OVER THE NEXT DAY AS AN EXPANSIVE MID-LATITUDE TROUGH THAT 
PREVIOUSLY WEAKENED THE STEERING RIDGE PULLS AWAY. TY 19W WILL MOVE 
STEADILY WESTWARD TO WEST-SOUTHWESTWARD UNDER THE CONTINUOUS 
STEERING INFLUENCE OF THE BUILDING RIDGE THROUGH THE FORECAST 
PERIOD. STEADY WEAKENING IS LIKELY AS PERSISTENT NORTHEASTERLY 
VERTICAL WIND SHEAR CONTINUES TO IMPACT THE SYSTEM. HOWEVER, PASSAGE 
OVER WARM WATER AND SUPPORTIVE UPPER-LEVEL OUTFLOW SHOULD PREVENT 
DISSIPATION PRIOR TO LANDFALL IN CENTRAL VIETNAM, WHICH IS 
ANTICIPATED TO OCCUR AFTER TAU 48. THE SYSTEM IS EXPECTED TO FULLY 
DISSIPATE OVER LAND BY TAU 72. 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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