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TROPICAL STORM DARBY DISCUSSION NUMBER   5
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT FRI JUL 24 1998
 
DEEP CONVECTION HAS INCREASED A LITTLE TONIGHT IN A SMALL AREA
AROUND THE CIRCULATION CENTER AND RATHER VIGOROUS BANDS ARE
NOTED...PARTICULARLY TO THE NW OF THE CENTER.  THE ESTIMATED WIND
SPEED BASED ON THE DVORAK TECHNIQUE IS NOW 50 KT.  INITIAL MOTION IS
285/9 KT.
 
DARBY/S MOTION APPEARS TO BE CONTROLLED PRIMARILY BY THE ANTICYCLONE
TO THE NORTH TO NORTHEAST.  A RATHER LARGE AREA OF CYCLONIC
CIRCULATION ALOFT...EVIDENT IN WATER VAPOR IMAGERY TO THE NORTHWEST
OF THE STORM...IS NOT INFLUENCING THE MOTION AT THIS TIME.  THE 00Z
AVN AND GFDL IMPLY SOME WESTWARD RIDGING OF THE HIGH TO THE NORTH OF
THE STORM.  THE TRACK FORECAST IS BASED ON THAT DEVELOPMENT AND
SHOWS A MOSTLY WNW TO W MOTION WITH SOME ACCELERATION.
 
A HIGH LEVEL SOUTHWESTERLY CURRENT IS IMPINGING ON THE NORTHWEST
PART OF THE CIRCULATION.  THIS HAS INTERFERED SOMEWHAT WITH THE
OUTFLOW THAT HAD BEEN MOSTLY UNIMPEDED IN THE WESTERN SEMICIRCLE
OVER THE PAST 24 HOURS.  AS YET...THIS FEATURE HAS NOT SIGNIFICANTLY
AFFECTED DARBY/S DEVELOPMENT.  FURTHER STRENGTHENING IS AGAIN
FORECAST AND IS CONSISTENT WITH THE EXPECTATION THAT THE SW SHEAR
WILL DIMINISH WHEN RIDGING TO THE NORTH BEGINS.
 
RAPPAPORT
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     24/0900Z 13.7N 115.8W    50 KTS
12HR VT     24/1800Z 14.0N 117.2W    60 KTS
24HR VT     25/0600Z 14.4N 119.2W    65 KTS
36HR VT     25/1800Z 14.7N 121.4W    75 KTS
48HR VT     26/0600Z 15.0N 123.8W    80 KTS
72HR VT     27/0600Z 15.5N 129.0W    80 KTS
 
 
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