Tropical Storm USAGI Advisory 11月24日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (USAGI)
WARNING NR 23//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 33W (USAGI), LOCATED APPROXIMATELY 205 NM
EAST-
SOUTHEAST OF HO CHI MINH, VIETNAM, HAS TRACKED WEST-SOUTHWESTWARD
AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED OVERALL CONVECTIVE
STRUCTURE WITH A SLIGHTLY EXPANDED RAIN BANDS. THE INITIAL
POSITION IS LINED UP WITH A CIRCULATION FEATURE IN THE 231420Z ASCAT
AMBIGUOUS IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 55
KNOTS BASED ON DVORAK ESTIMATES OF T3.5/55KTS FROM ALL THREE
REPORTING AGENCIES. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE
ENVIRONMENT WITH LOW TO MODERATE (15-20 KT) EASTERLY VERTICAL WIND
SHEAR AND VIGOROUS POLEWARD OUTFLOW. TS 33W IS CURRENTLY TRACKING
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 USAGI WILL CONTINUE TRACKING WESTWARD ALONG THE SOUTHERN
PERIPHERY OF THE STR BUT SHOULD GRADUALLY TURN WEST-NORTHWESTWARD
AFTER TAU 24 AS THE STR RECEDES. TS 33W IS EXPECTED TO INTENSIFY
SLIGHTLY DUE TO THE FAVORABLE ENVIRONMENTAL CONDITIONS TO A PEAK OF
60 KNOTS AT TAUS 12-24. THE CYCLONE WILL MAKE LANDFALL BY TAU 30 JUST
SOUTH OF HO CHI MINH AND WILL WEAKEN RAPIDLY AS IT TRACKS INLAND WITH
DISSIPATION FORECAST BY TAU 72. OVERALL, THERE IS HIGH CONFIDENCE IN
THE JTWC OFFICIAL FORECAST TRACK, WHICH IS POSITIONED NEAR THE
MULTI-MODEL CONSENSUS.//
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