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TROPICAL STORM BORIS DISCUSSION NUMBER 4
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT SUN JUN 09 2002
THE INITIAL MOTION ESTIMATE IS 300/07. THE TRACK GUIDANCE SUGGESTS
VERY SLOW MOTION TOWARD THE WEST-NORTHWEST FOR THE NEXT 72 HOURS
WITH A WEAK MID-LEVEL RIDGE OVER NORTHERN MEXICO AND A WEAK TROUGH
JUST NORTHWEST OF THE STORM. THE OFFICIAL TRACK FORECAST HAS A
LITTLE SLOWER FORWARD SPEED THAN THE PREVIOUS ADVISORY.
DVORAK ESTIMATES FRO TAFB AND SAB ARE 55 AND 45 KNOTS AS A RATHER
IMPRESSIVE CDO FEATURE RECENTLY FORMED. HOWEVER THE CLOUD TOPS HAVE
WARMED AGAIN EVEN MORE RECENTLY SO THE WIND SPEED IS INCREASED TO
ONLY 45 KNOTS. THE SHIPS MODEL DIAGNOSES 18 KNOTS OF VERTICAL SHEAR
FROM THE GFS MODEL OVER THE STORM...INCREASING TO 28 KNOTS IN 48
HOURS. THEREFORE THE OFFICIAL WIND SPEED FORECAST PEAKS AT 55 KNOTS
AT 12 THROUGH 36 HOURS FOLLOWED BY WEAKENING.
THE STORM IS MOVING PARALLEL TO THE COAST OF MEXICO AND THE STRONG
WINDS AND HEAVIEST RAINFALL REMAIN OFF SHORE...SO THE TROPICAL STORM
WATCH FOR THE COAST IS NOT CHANGED.
FORECASTER LAWRENCE
FORECAST POSITIONS AND MAX WINDS
INITIAL 09/0900Z 17.2N 104.9W 45 KTS
12HR VT 09/1800Z 17.7N 105.6W 55 KTS
24HR VT 10/0600Z 18.2N 106.3W 55 KTS
36HR VT 10/1800Z 18.6N 107.0W 55 KTS
48HR VT 11/0600Z 18.9N 107.6W 50 KTS
72HR VT 12/0600Z 19.5N 108.5W 40 KTS
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