Tropical Storm ALEX

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TROPICAL STORM ALEX DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012010
1000 AM CDT MON JUN 28 2010
 
ALTHOUGH THE CLOUD PATTERN OF ALEX HAS BECOME A LITTLE DISTORTED
THIS MORNING...THE CYCLONE HAS CONTINUED TO GRADUALLY INTENSIFY. AN
AIR FORCE RESERVE RECONNAISSANCE PLANE FOUND PEAK FLIGHT-LEVEL
WINDS OF 66 KT...SFMR VALUES OF 51 KT...AND A DECREASE IN PRESSURE
TO 989 MB. THUS THE INITIAL INTENSITY IS INCREASED A BIT TO 50 KT.
 
THE INITIAL MOTION IS 330/5...TO THE RIGHT OF PREVIOUS ESTIMATES. AN
UPPER-LEVEL TROUGH SEEN TO THE NORTH OF THE STORM MAY BE
CONTRIBUTING TO THE MORE POLEWARD MOTION BY CAUSING A WEAKENING OF
THE RIDGE OVER THE GULF COAST. THIS TROUGH IS FORECAST TO LIFT OUT
OF THE AREA IN A DAY OR SO...WHICH SHOULD ALLOW RIDGING TO BUILD
BACK IN SLIGHTLY AND STEER ALEX MORE TOWARD THE NORTHWEST. AFTER
THAT TIME...THE STRENGTH OF A RIDGE OVER THE CENTRAL PLAINS SHOULD
HELP DETERMINE WHETHER THE TROPICAL CYCLONE CONTINUES A
NORTHWESTWARD MOTION OR MAKES MORE OF A TURN TOWARD THE
WEST-NORTHWEST. THE MODEL GUIDANCE IS IN PRETTY GOOD AGREEMENT
THROUGH 48 HOURS...THEN HAS A BIT MORE SPREAD. THERE HAS BEEN A
SUBTLE SHIFT NORTHWARD WITH SOME OF THE 06Z GUIDANCE...AND THE NHC
FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION.
 
SOME NORTHWESTERLY SHEAR IS CURRENTLY AFFECTING ALEX...ALTHOUGH THIS
HAS NOT PREVENTED THE STORM FROM SLOWLY DEEPENING.  THIS SHEAR IS
FORECAST TO ABATE BY TOMORROW AS THE UPPER-LEVEL TROUGH PULLS OUT
OF THE GULF OF MEXICO...WHICH COULD THEN ALLOW FOR MORE SIGNIFICANT
STRENGTHENING.  THE STATISTICAL MODELS CONTINUE TO SHOW MORE
INTENSIFICATION OF ALEX THAN THE DYNAMICAL GUIDANCE...WHICH SEEMS
REASONABLE GIVEN THE LIKELY ENVIRONMENTAL CONDITIONS.  THE NHC
FORECAST IS CLOSE TO THE STATISTICAL MODELS AND THE PREVIOUS
FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/1500Z 20.3N  91.7W    50 KT
 12HR VT     29/0000Z 21.1N  92.1W    55 KT
 24HR VT     29/1200Z 22.3N  92.9W    65 KT
 36HR VT     30/0000Z 23.5N  94.2W    75 KT
 48HR VT     30/1200Z 24.3N  95.5W    85 KT
 72HR VT     01/1200Z 25.5N  97.7W    80 KT...INLAND
 96HR VT     02/1200Z 26.5N  99.5W    35 KT...INLAND
120HR VT     03/1200Z 27.5N 101.5W    20 KT...DISSIPATING INLAND
 
$$
FORECASTER BLAKE/BRENNAN
 
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