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HURRICANE DARBY DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT FRI JUL 24 1998
 
THE INITIAL MOTION ESTIMATE IS 290/10.  THE TRACK GUIDANCE MODELS
ALL SHOW A WEST-NORTHWESTWARD MOTION WITH SOME ACCELERATION THROUGN
72 HOURS...ALTHOUGH IT IS NOT CLEAR FROM THE AVIATION MODEL 12Z RUN
AS TO WHY THE MOTION SHOULD ACCELERATE.  THE OFFICIAL FORECAST IS
ADJUSTED SLIGHTLY TO THE RIGHT OF THE PREVIOUS ADVISORY AND SHOWS
ONLY A SMALL ACCELERATION.

SATELLITE IMAGERY SHOWS A WELL DEFINED EYE HAS FORMED OVER THE PAST
FEW HOURS AND THE INITIAL INTENSITY IS INCREASED TO 80 KNOTS.  THIS
IS BETWEEN THE 4.5 DVORAK T NUMBER FROM TAFB AND THE 5.0 T NUMBER
FROM SAB.  THE ONLY FACTOR TO AFFECT THE INCREASING INTENSITY TREND
IS THAT THE TRACK MOVES OVER SLIGHTLY COOLER WATER AFTER 36 HOURS.

LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     24/2100Z 14.7N 117.8W    80 KTS
12HR VT     25/0600Z 15.2N 119.3W    90 KTS
24HR VT     25/1800Z 16.0N 121.5W   100 KTS
36HR VT     26/0600Z 16.7N 124.2W   100 KTS
48HR VT     26/1800Z 17.5N 127.0W    90 KTS
72HR VT     27/1800Z 18.5N 132.0W    75 KTS
 
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