HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDAT1
TTAA00 KNHC DDHHMM
TROPICAL STORM ARLENE DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT SAT JUN 12 1999
 
TROPICAL DEPRESSION ONE HAS BECOME CONSIDERABLY BETTER ORGANIZED
OVER THE LAST 24 HOURS.  MOREOVER...DURING THE LAST 6 HOURS
CONVECTION HAS INCREASED NEAR THE CENTER.  DVORAK CLASSIFICATIONS
REFLECT THE DEVELOPMENT TREND AS BOTH TAFB AND SAB NOW HAVE A CI
NUMBER OF 2.5.  THUS...TROPICAL DEPRESSION ONE IS BEING UPGRADED 
TO TROPICAL STORM ARLENE.  

THE INITIAL MOTION ESTIMATE IS 330/03 KNOTS.  THE FIXES FROM TAFB
...SAB AND AFGWC ARE IN GOOD AGREEMENT AND SUGGEST THAT THE CENTER
HAS DRIFTED NORTH-NORTHWEST OVER THE LAST 6 HOURS. THE TRACK MODEL
GUIDANCE CONTINUES TO SHOW CONSIDERABLE SCATTER WITH THE STATISTICAL
MODELS SHOWING A NORTHWARD MOTION WHILE MOST OF THE DYNAMIC MODELS
SHOW A NORTH-NORTHWEST TO NORTHWEST HEADING. THE GFDL FOLLOWS THE
LATTER SCENARIO THRU 24 HRS THEN TURNS THE CYCLONE WEST THEN
SOUTHWEST.  THE REASONING BEHIND THE OFFICIAL FORECAST REMAINS
UNCHANGED FROM THE PREVIOUS PACKAGE. THE LATEST NHC TRACK IS 
SLIGHTLY LEFT OF THE PREVIOUS ADVISORY BASED ON THE INITIAL MOTION
AND STILL HOLDS TO A VERY SLOW NORTH-NORTHWEST DRIFT THRU 72 HRS.

THE INTENSITY FORECAST BRINGS ARLENE TO 45 KNOTS BY 24 HRS WITH
NO CHANGE THEREAFTER.
 
GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/1500Z 28.4N  57.5W    35 KTS
12HR VT     13/0000Z 28.7N  57.6W    40 KTS
24HR VT     13/1200Z 29.2N  57.8W    45 KTS
36HR VT     14/0000Z 29.6N  58.0W    45 KTS
48HR VT     14/1200Z 30.0N  58.5W    45 KTS
72HR VT     15/1200Z 30.5N  59.0W    45 KTS
 
 
NNNN