Tropical Storm BAVI Advisory 8月23日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (BAVI) WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (BAVI), LOCATED APPROXIMATELY 225 NM WEST
OF KADENA AB, HAS TRACKED NORTHWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM WITH FLARING CONVECTION WRAPPING INTO A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER. THE CONVECTION IS STILL STRONG
OVER THE SOUTHERN SEMICIRCLE, BUT THE CONVECTION TO THE NORTH REMAINS
LIMITED DUE TO THE UPPER LEVEL CONVERGENCE POSITIONED TO THE
NORTHWEST. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE BASED
ON THE LOW LEVEL CIRCULATION FEATURES PRESENT IN THE EIR LOOP AND A
1755 ATMS 88GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY IS ALSO PLACED
WITH GOOD CONFIDENCE, HEDGED SLIGHTLY ABOVE MULTIAGENCY DVORAK
CURRENT INTENSITY ESTIMATES OF T3.0 (45 KNOTS).  THE SYSTEM IS
TRACKING GENERALLY NORTHWARD ALONG AN EXTENSION OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE SOUTHEAST AND THROUGH AN ENVIRONMENT
FAVORABLE FOR INTENSIFICATION WITH VERY WARM (30-31 CELSIUS) SEA
SURFACE TEMPERATURES, LOW (10-15 KTS) VERTICAL WIND SHEAR AND WELL
ESTABLISHED EQUATORWARD OUTFLOW IN THE UPPER LEVELS.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 36, TS BAVI WILL CONTINUE TO TRACK GENERALLY
NORTHEASTWARD AS IT ROUNDS THE STR POSITIONED TO THE SOUTHEAST BEFORE
TURNING NORTH-NORTHWESTWARD AS THE STR REORIENTS. AN UPPER LEVEL
TROUGH PASSING TO THE NORTH IS EXPECTED TO INTERACT WITH THE SYSTEM
THROUGH THE NEXT 24 HOURS AND DIMINISH SLIGHTLY DIMINISH THE UPPER
LEVEL OUTFLOW BETWEEN TAU 24 TO TAU 48. DESPITE THIS, LOW VERTICAL
WIND SHEAR AND VERY WARM SSTS WILL LIKELY ALLOW FOR FURTHER, AND
POSSIBLY RAPID, INTENSIFICATION TO 90 KTS BY TAU 48. HOWEVER,
INTENSITY GUIDANCE DURING THIS PERIOD GIVES WIDE VARIANCE AND LENDS
POOR CONFIDENCE TO THE JTWC INTENSITY FORECAST.
   C. AFTER TAU 72, DESPITE MODERATE TO STRONG (20-25 KTS) VWS,
CONTINUED WARM SSTS AND IMPROVING UPPER LEVEL OUTFLOW WILL LEAD TO
FURTHER INTENSIFICATION DURING THIS NORTHWARD TRACK AND ALLOW THE
SYSTEM TO REACH A MAXIMUM INTENSITY OF 100 KTS BY TAU 72. THERE IS A
FAIR DEGREE OF UNCERTAINTY IN MODEL SOLUTIONS DURING THIS PERIOD DUE
TO THE TIMING OF THE SHORTWAVE TROUGH MOVEMENT, WITH A 290 NM SPREAD
IN ALONG TRACK SPREAD BY TAU 96. THE SYSTEM IS EXPECTED TO MAKE
LANDFALL AFTER TAU 96 AND RAPIDLY DETERIORATE AS IT MOVES INLAND DUE
TO FRICTIONAL EFFECTS. THERE IS ONLY FAIR CONFIDENCE IN THE JTWC
FORECAST TRACK.
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