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TROPICAL STORM ARLENE DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SAT JUN 12 1999
 
ARLENE HAS CONTINUED TO BECOME BETTER ORGANIZED THIS EVENING.  THE
CDO IS STILL IN PLACE AND CENTER APPEARS TO BE EMBEDDED IN IT.  THE
SYSTEM MAINTAINS GOOD UPPER-LEVEL OUTFLOW AND HAS NOT BEEN SHEARED
BY APPROACHING UPPER-LEVEL WESTERLIES.  DVORAK INTENSITY ESTIMATES
FROM TAFB AND SAB ARE NOW 55 KT AND 45 KT...RESPECTIVELY AND AIR
FORCE GLOBAL IS AT 35 KT.  TAFB METEOROLOGIST HAS NOTED THAT
SATELLITE IMAGES SHOW THAT MAIN INFLOW IN THE LOW LEVELS IS FROM THE
SOUTH AND SOUTHEAST AND LITTLE OR NO INFLOW FROM STABLE AIR IN HIGH
TO THE NORTH...WHICH HAS BLOCKED THE SYSTEM.  THIS MAY BE MAIN
REASON WHY ARLENE HAS BEEN ABLE TO INTENSIFY OVER THESE COOL SSTS. 
THUS...THE INITIAL INTENSITY WILL BE RAISED TO 45 KT. ARLENE IS
INTENSIFYING AT THE RATE OF 5 KNOTS EVERY 6-HOURS SO 12 HOUR
FORECAST IS 55 KNOTS.  INTENSITY FORECAST TO 60 KNOTS AT 24 HOURS
AND HELD STEADY AT THIS VALUE.  HOWEVER...IF TREND CONTINUES...MAY
HAVE A HURRICANE IN 24 HOURS.
 
THE LATEST SATELLITE FIXES FROM TAFB AND SAB SHOW THAT ARLENE
HAS BEEN WOBBLING NORTHWARD AND THE INITIAL MOTION IS 360/03
KNOTS. HOWEVER...LATEST IR ANIMATION SUGGESTS A WOBBLE TOWARD THE
NORTH-NORTHWEST.
 
GUIDANCE MODELS ARE STARTING TO AGREE ON DIRECTION OF MOTION FOR
ARLENE.  UKMET..AVN..NOGAPS..GFDL..BAMM AND BAMS MOVE SYSTEM SLOWLY
IN A GENERAL NORTHWEST TO WEST DIRECTION OUT TO 36 HOURS.  AFTER 36
HOURS...DIFFERENT ACCELERATIONS IN SPEED CAUSE TRACKS TO DIVERGE. 
THE OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS PACKAGE WITH A
NORTH/NORTHWEST DRIFT THROUGH 72 HOURS.
 
JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/0300Z 29.2N  57.4W    45 KTS
12HR VT     13/1200Z 29.5N  57.5W    55 KTS
24HR VT     14/0000Z 29.8N  57.7W    60 KTS
36HR VT     14/1200Z 30.2N  58.1W    60 KTS
48HR VT     15/0000Z 30.4N  58.6W    60 KTS
72HR VT     16/0000Z 30.8N  59.6W    60 KTS
 
 
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