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TROPICAL STORM ARLENE DISCUSSION NUMBER   5
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT JUN 12 1999
 
ARLENE HAS CONTINUED TO BECOME BETTER ORGANIZED TODAY AS THE
CENTER IS NOW JUST UNDERNEATH A SMALL CDO. THE SYSTEM HAS GOOD
OUTFLOW OVER THE NORTHERN SEMICIRCLE AND RESTRICTED ELSEWHERE.
DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 KT AND
35 KT...RESPECTIVELY.  THUS...THE INITIAL INTENSITY WILL BE
RAISED TO 40 KT. THE INTENSITY FORECAST BRINGS ARLENE TO 45
KNOTS BY 12 HRS WITH NO CHANGE THEREAFTER.
 
THE LATEST SATELLITE FIXES FROM TAFB AND SAB SHOW THAT ARLENE
HAS BEEN DRIFTING NORTHWARD AND THE INITIAL MOTION IS 360/02
KNOTS. THE SYSTEM IS IN A WEAK STEERING ENVIRONMENT BETWEEN
TWO MID- TO UPPER LEVEL LOWS...ONE JUST OFF THE MID ATLANTIC
COAST AND ANOTHER ABOUT 500 MILES WEST OF THE AZORES.
 
THE GUIDANCE MODELS HAVE NOW SPLIT INTO TWO CAMPS...ONE WHICH
MOVES ARLENE NORTH/NORTHWEST (UKMET..AVN) AND ANOTHER WHICH
SHOWS AN INITIAL NORTHEAST (LBAR) OR NORTHWEST (BAMD) MOTION
FOLLOWED BY A SHARP TURN TO THE SOUTH/SOUTHWEST. THE GFDL
FOLLOWS THE FORMER SOLUTION THROUGH 24 HOURS BEFORE TURNING
WEST. WITH THE EXCEPTION OF THE UKMET THEY ALL AGREE ON A SLOW
FORWARD MOTION. THE OFFICIAL FORECAST IS VERY SIMILAR TO THE
PREVIOUS PACKAGE WITH A NORTH/NORTHWEST DRIFT THROUGH 72 HOURS.
 
GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/2100Z 28.6N  57.4W    40 KTS
12HR VT     13/0600Z 29.0N  57.5W    45 KTS
24HR VT     13/1800Z 29.4N  57.7W    45 KTS
36HR VT     14/0600Z 29.8N  57.9W    45 KTS
48HR VT     14/1800Z 30.3N  58.3W    45 KTS
72HR VT     15/1800Z 31.0N  59.5W    45 KTS
 
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