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TROPICAL STORM ALEX DISCUSSION NUMBER  19
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT FRI JUL 31 1998
 
ALEX IS STILL GENERATING A FEW CLUSTERS OF DEEP CONVECTION OVER THE
NORTHERN PART OF ITS CIRCULATION AND...AS SUGGESTED BY DVORAK
TECHNIQUE ANALYSES...THE SYSTEM IS PROBABLY STILL A TROPICAL STORM.
ESTIMATED WINDS ARE 35 KT.  DATA FROM THE NOAA HIGH-ALTITUDE JET
SEEMS TO CONFIRM THE PRESENCE OF A MID- TO UPPER-LEVEL SHEARING
PATTERN MAINLY BELOW ALEX/S CIRRUS CANOPY LEVEL.
 
THE INITIAL MOTION IS 275/11 KT.  TRACK FORECASTING BECOMES MORE
DIFFICULT THAN USUAL WHEN...LIKE NOW...IT IS ALSO TIED TO A HIGHLY
UNCERTAIN INTENSITY FORECAST.  THERE APPEAR TO BE THREE PRIMARY
POSSIBILITIES.  FIRST...IF THE SHEAR SOMEWHAT UNEXPECTEDLY DECREASES
THEN ALEX COULD STRENGTHEN AND TURN MORE TOWARD THE WNW OR NW...
DIMINISHING ANY THREAT TO THE CARIBBEAN.  SECOND...ALEX COULD WEAKEN
FURTHER OR DISSIPATE WITH ITS REMNANTS MOVING NEARLY WESTWARD...
AGAIN HAVING MINIMAL IMPACT ON THE CARIBBEAN.  THIRD...THE SYSTEM
COULD REMAIN MUCH AS IT IS...UNIMPRESSIVE ON SATELLITE PICTURES...
BUT A POTENTIAL PRODUCER OF SOME HEAVY RAIN AND THE POSSIBILITY OF
LOCAL FLOODING AND HIGH WIND GUSTS FOR THE LEEWARD ISLANDS HAVING
HIGH TERRAIN.
 
WITH SHEAR EXPECTED TO PERSIST...THE SECOND SCENARIO MIGHT BE THE
MOST LIKELY.  HOWEVER...PARTLY TO BE CAUTIONS...THE CURRENT FORECAST
HAS A LITTLE MORE OF AN INKLING OF THE THIRD POSSIBILITY THAN WE
HAVE INDICATED PREVIOUSLY.  THE TRACK IS SHIFTED TO THE LEFT A
LITTLE AND IF THIS TREND IS OBSERVED OVER THE NEXT 12-24 HOURS
...SOME CONSIDERATION WILL BE GIVEN TO ISSUING A TROPICAL
STORM WATCH OR WARNING FOR A PORTION OF THE LEEWARD ISLANDS ON
SATURDAY.  THE NHC TRACK IS BETWEEN BAMS AND CLIPER...WHICH FORM THE
SOUTHERN EXTREME OF TONIGHT/S MODEL GUIDANCE.
 
RAPPAPORT
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/0300Z 16.1N  52.1W    35 KTS
12HR VT     01/1200Z 16.3N  53.8W    35 KTS
24HR VT     02/0000Z 16.9N  56.6W    35 KTS
36HR VT     02/1200Z 17.9N  59.4W    35 KTS
48HR VT     03/0000Z 19.2N  61.6W    35 KTS
72HR VT     04/0000Z 22.0N  65.0W    35 KTS
 
 
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