Tropical Storm SAUDEL Advisory 10月24日

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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