443 
 WTNT41 KNHC 282037
 TCDAT1
 TROPICAL STORM ALEX DISCUSSION NUMBER  13
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012010
 400 PM CDT MON JUN 28 2010
  
 DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT SUGGEST
 THAT THE INTENSITY OF ALEX HAS CHANGED LITTLE OVER THE PAST FEW
 HOURS. THE LAST PRESSURE MEASURED WAS 990 MB...UP JUST A BIT FROM
 THIS MORNING. DATA FROM THE SFMR ON THE AIRCRAFT SUPPORT
 MAINTAINING THE INTENSITY AT 50 KT. ALEX IS EXPERIENCING NORTHERLY
 WIND SHEAR OF ABOUT 10 TO 15 KNOTS ACCORDING TO THE SHIPS MODEL AND
 ANALYSES FROM UW-CIMSS. THE SHEAR IN COMBINATION WITH SOME DRY AIR
 IN THE NORTHERN PART OF THE CIRCULATION HAVE LIKELY BEEN
 RESPONSIBLE FOR THE SPOTTY NATURE OF THE DEEP CONVECTION NEAR THE
 CENTER OF ALEX TODAY. ALSO...SINCE ALEX HAS BEEN SITUATED OVER THE
 SHALLOW SHELF WATERS WEST OF THE YUCATAN ALL DAY...SOME UPWELLING
 OF COOL WATER COULD BE HINDERING DEVELOPMENT FOR THE TIME BEING.
  
 ONCE THE MID TO UPPER-LEVEL TROUGH OVER THE NORTHERN GULF OF MEXICO
 MOVES AWAY FROM ALEX...THE ENVIRONMENT SHOULD BECOME MORE FAVORABLE
 FOR INTENSIFICATION AS THE SHEAR DECREASES AND ALEX MOVES TOWARD A
 WARM EDDY IN THE SOUTHWESTERN GULF. THE OFFICIAL NHC INTENSITY
 FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE...AND IS CLOSE TO A
 BLEND OF THE SHIPS AND LGEM MODELS...WHICH ARE THE STRONGEST OF THE
 INTENSITY MODELS. ALSO...ALEX COULD STRENGTHEN A LITTLE MORE BEFORE
 LANDFALL BEYOND WHAT IS SHOWN IN THE 48-HOUR FORECAST...BUT NONE OF
 THE GUIDANCE SHOWS ALEX REACHING MAJOR HURRICANE INTENSITY AT THIS
 TIME.
  
 ALEX HAS MOVED LITTLE OVER THE PAST FEW HOURS...BUT THE BEST
 LONG-TERM INITIAL MOTION ESTIMATE IS TOWARD THE NORTH-NORTHWEST...
 330 DEGREES...AT 4 KNOTS. AFTER THE UPPER-LEVEL TROUGH OVER THE
 NORTHERN GULF MOVES EAST...THE GLOBAL MODELS ARE NOW IN GENERALLY
 GOOD AGREEMENT IN BUILDING A RIDGE TO THE NORTH OF ALEX. THIS
 SHOULD RESULT IN A TURN TOWARD THE NORTHWEST AND THEN TOWARD THE
 WEST-NORTHWEST OVER THE NEXT COUPLE OF DAYS...WITH AN INCREASE IN
 FORWARD SPEED. COMPARED TO YESTERDAY...THE TRACK GUIDANCE IS IN
 BETTER AGREEMENT ON THIS SCENARIO AND HAS GENERALLY TRENDED
 SOUTHWARD AND FASTER WITH THE FORWARD SPEED. ACCORDINGLY...THE
 OFFICIAL FORECAST HAS BEEN ADJUSTED TO THE LEFT AND SHOWS AN
 INCREASE IN FORWARD SPEED...BUT NOW LIES TO THE RIGHT OF MOST OF
 THE DYNAMICAL MODELS.
  
 A HURRICANE WARNING MAY BE REQUIRED FOR A PORTION OF THE HURRICANE
 WATCH AREA TONIGHT.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      28/2100Z 20.5N  91.8W    50 KT
  12HR VT     29/0600Z 21.5N  92.4W    60 KT
  24HR VT     29/1800Z 22.9N  93.7W    65 KT
  36HR VT     30/0600Z 23.8N  95.1W    75 KT
  48HR VT     30/1800Z 24.5N  96.4W    80 KT
  72HR VT     01/1800Z 25.5N  99.5W    60 KT...INLAND
  96HR VT     02/1800Z 26.0N 101.0W    25 KT...INLAND
 120HR VT     03/1800Z...DISSIPATED
  
 $$
 FORECASTER BRENNAN