Tropical Storm BAVI Advisory 8月27日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 09W (BAVI), LOCATED APPROXIMATELY 120 NM WEST OF OSAN AB,
HAS TRACKED NORTHWARD AT 21 KNOTS (KTS) OVER THE PAST SIX HOURS.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES THAT THE
SYSTEM IS RAPIDLY DECOUPLING UNDER INCREASING VWS, WITH THE EYE THAT
WAS EVIDENT JUST SIX HOURS BEFORE, NOW COMPLETELY DISSIPATED IN THE
EIR IMAGERY. THE INITIAL POSITION IS PLACED WELL WEST OF THE MAJORITY
OF AGENCY FIXES AND JUST SOUTHWEST OF THE PGTW POSITION FIX, BASED ON
A HIGH CONFIDENCE ASSESSMENT OF RADAR DATA, BUOY DATA AND A 261741Z
AMSR2 37 GHZ MICROWAVE IMAGE WHICH SHOWS A CLEAR CUT LOW LEVEL
CIRCULATION CENTER SIGNIFICANTLY DECOUPLED FROM THE UPPER-LEVEL
ROTATION. THE CURRENT INTENSITY OF 80 KNOTS IS ASSESSED WITH MODERATE
CONFIDENCE ON THE UPPER END OF DVORAK CURRENT INTENSITY ESTIMATES OF
T4.0 TO T4.5 FROM PGTW AND RJTD, AND AN ADT ESTIMATE OF T4.5.
ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM LIES IN A GENERALLY
HOSTILE ENVIRONMENT, WITH VWS ESTIMATED AT BETWEEN 20-30 KNOTS, SSTS
LESS THAN 23 DEG (CELSIUS) BASED ON BUOY DATA, AND STRONG POLEWARD
OUTFLOW. HOWEVER, THE OUTFLOW IS NOW BEING OFFSET BY THE SHEAR AS
REFLECTED BY THE DECOUPLING OF THE SYSTEM OVER THE PAST SIX HOURS. TY
09W IS TRACKING NORTHWARD ALONG THE WESTERN PERIPHERY OF A
SUBTROPICAL RIDGE POSITIONED TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. FOR THE REMAINDER OF THE FORECAST, TY 09W WILL TRACK NORTH-
NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF THE DEEP-LAYER STR
CENTERED TO THE EAST. DUE TO THE RAPIDLY INCREASING VWS, COOLING SSTS
AND DRY AIR ENTRAINMENT, TY 09W WILL CONTINUE TO RAPIDLY WEAKEN AS IT
TRACKS POLEWARD. THE SYSTEM IS FORECAST TO MAKE LANDFALL WEST OF
CHANGYON PRIOR TO 270000Z. THE SYSTEM IS ALREADY STARTING TO SHOW
SOME INITIAL SIGNS OF BECOMING EXTRATROPICAL, AND IS FORECAST TO
COMPLETE EXTRATROPICAL TRANSITION BY TAU 24 AS IT EMBEDS WITHIN THE
UPPER-LEVEL WESTERLIES OVER NORTHEASTERN CHINA. DYNAMIC MODEL
GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 12 BUT THEREAFTER SHOWS
RAPIDLY INCREASE DIVERGENCE IN MODEL SOLUTIONS AS THE TRACKERS LOSE
THE LLCC. THE GFS AND NVGM MODELS INDICATE A QUASI-STATIONARY OR
WESTWARD LOOPING TRACK AFTER TAU 24, WHILE THE REMAINDER OF THE
CONSENSUS MODELS CONTINUE TRACKING THE SYSTEM RAPIDLY NORTHEASTWARD.
THE JTWC FORECAST TRACK LIES JUST EAST OF THE MULTI-MODEL CONSENSUS
AND FAVORS THE ECMWF SOLUTION THROUGH THE ENTIRE FORECAST PERIOD,
WITH HIGH CONFIDENCE.//
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