Tropical Storm ALEX

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TROPICAL STORM ALEX DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012010
1000 AM CDT TUE JUN 29 2010
 
SATELLITE IMAGERY SHOWS THAT ALEX HAS A SOMEWHAT RAGGED APPEARANCE
THIS MORNING...WITH A CONVECTIVE BURST OCCURRING JUST EAST OF THE
CENTER AND AN APPARENT DRY SLOT WEST OF THE CENTER.  AN AIR FORCE
RESERVE HURRICANE HUNTER AIRCRAFT REPORTED 850 MB FLIGHT-LEVEL
WINDS OF 70 KT AND SFMR WINDS OF 57 KT IN THE NORTHEAST QUADRANT...
THE LATTER ABOUT 20 NM FROM THE CENTER.  THE MINIMUM CENTRAL
PRESSURE WAS 982 MB.  BASED ON THE AIRCRAFT WINDS...THE INITIAL
INTENSITY REMAINS 60 KT.  THE CIRRUS OUTFLOW IS FAIR TO THE NORTH
AND EAST...AND POOR ELSEWHERE.

ALEX HAS TURNED LEFT AND ACCELERATED DURING THE PAST SEVERAL HOURS. 
THE 12 HR MOTION IS 325/10...AND THE SHORT-TERM MOTION MAY BE
FASTER.  RAWINSONDE DATA THIS MORNING SHOW HEIGHT RISES FROM
850-500 MB OVER LOUISIANA AND TEXAS...INDICATING THE LOW/MID-LEVEL
RIDGE IN THIS AREA IS STRENGTHENING AS FORECAST BY THE LARGE-SCALE
MODELS.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT THAT ALEX WILL
GRADUALLY TURN WEST-NORTHWESTWARD AND WESTWARD ON THE SOUTH SIDE OF
THIS RIDGE AS IT STRENGTHENS FURTHER DURING THE NEXT 24-48 HR. 
INDEED...THE ECMWF AND THE NAM SUGGEST ALEX COULD TURN SOUTH OF
WEST AFTER IT MAKES LANDFALL.  THE NEW FORECAST TRACK IS SHIFTED A
LITTLE TO THE SOUTH AND IS FASTER THAN THE PREVIOUS TRACK BASED ON
CURRENT POSITION AND MOTION.  HOWEVER...IT STILL LIES NORTH OF THE
CONSENSUS MODELS AND THE CENTER OF THE GUIDANCE ENVELOPE.  OF THE
DYNAMICAL GUIDANCE...ONLY THE HWRF AND NOGAPS ARE CURRENTLY NORTH
OF THE OFFICIAL FORECAST.
 
THE CENTRAL CONVECTIVE BURST IS PRODUCING TOPS COLDER THAN
-80C...AND THE AIRCRAFT IS REPORTING A PARTIAL EYEWALL.  THESE ARE
SIGNS THAT ALEX COULD STRENGTHEN SOON.  ON THE OTHER HAND...THE
OUTFLOW IS RESTRICTED ON THE WEST SIDE WHERE THERE IS APPARENTLY
SOME DRY AIR ENTRAINMENT.  IN ADDITION...THE GFDL...HWRF...AND GFDN
DO NOT FORECAST SIGNIFICANT STRENGTHENING DESPITE A SEEMINGLY
FAVORABLE LIGHT-SHEAR WARM-WATER ENVIRONMENT.  THE SHIPS AND LGEM
MODELS CONTINUE TO FORECAST ALEX TO BECOME A HURRICANE...AND THE
NEW INTENSITY FORECAST FOLLOWS SUIT.  THE NEW FORECAST IS AN UPDATE
OF THE PREVIOUS FORECAST AND LIES AT THE UPPER EDGE OF THE
INTENSITY GUIDANCE ENVELOPE.
 
THE AIRCRAFT DATA SHOW THAT THE 34 KT WIND RADII HAVE EXPANDED OVER
ALL QUADRANTS EXCEPT THE SOUTHWEST.  BETWEEN THIS AND THE FASTER
FORWARD MOTION...THERE IS NOW ABOUT 12 HOURS LESS TIME TO MAKE
PREPARATIONS BEFORE THE ONSET OF TROPICAL-STORM FORCE WINDS IN THE
WARNING AREA THAN COMPARED TO THE PREVIOUS FORECAST. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/1500Z 22.7N  93.1W    60 KT
 12HR VT     30/0000Z 23.7N  94.0W    65 KT
 24HR VT     30/1200Z 24.7N  95.5W    75 KT
 36HR VT     01/0000Z 25.2N  97.0W    80 KT
 48HR VT     01/1200Z 25.7N  98.7W    50 KT
 72HR VT     02/1200Z 26.0N 101.5W    25 KT...DISSIPATING INLAND
 96HR VT     03/1200Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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