549 
 WTNT41 KNHC 201450
 TCDAT1
  
 TROPICAL STORM ALBERTO DISCUSSION NUMBER   4
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012012
 1100 AM EDT SUN MAY 20 2012
  
 THE CENTER OF ALBERTO HAS BECOME MORE EXPOSED THIS MORNING...AND THE
 DEEPEST CONVECTION APPEARS TO BE MOVING WESTWARD AWAY FROM THE
 SYSTEM.  OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES ARE ALL
 SUGGESTING AN INTENSITY AROUND 35 KT...BUT THE ADVISORY INTENSITY
 IS ONLY BEING LOWERED TO 40 KT FOR NOW.  AN AIR FORCE HURRICANE
 HUNTER IS SCHEDULED TO INVESTIGATE THE SYSTEM THIS AFTERNOON...AT
 WHICH TIME ADDITIONAL ADJUSTMENTS CAN BE MADE.
  
 ALBERTO APPEARS TO HAVE AT LEAST THREE STRIKES AGAINST ANY
 RE-INTENSIFICATION.  FIRST...DEWPOINTS OVER SOUTHEASTERN U.S. ARE
 ROUGHLY 50 DEGREES FAHRENHEIT...AND THE CYCLONE IS LIKELY INGESTING
 SOME OF THIS DRY AIR.  SECOND...THE CENTER IS MOVING WEST OF THE
 GULF STREAM OVER COOLER SHELF WATERS NEAR THE SOUTH CAROLINA/
 GEORGIA COAST.  AND THIRD...UPPER-LEVEL WESTERLY WINDS ARE EXPECTED
 TO INCREASE OVER THE SYSTEM DURING THE NEXT 24 HOURS.  THE OFFICIAL
 FORECAST THEREFORE KEEPS ALBERTO AT LOW-END TROPICAL-STORM STRENGTH
 THROUGH WEDNESDAY WITH WEAKENING AND DISSIPATION OCCURRING ON
 THURSDAY.  THIS SCENARIO IS SUPPORTED BY VIRTUALLY ALL OF THE
 INTENSITY GUIDANCE.  ALBERTO IS FORECAST TO BECOME POST-TROPICAL BY
 72 HOURS...ALTHOUGH THERE IS CONSIDERABLE UNCERTAINTY ON THE EXACT
 TIMING OF THAT TRANSITION.
  
 A BLOCKING PATTERN OVER THE EASTERN UNITED STATES HAS CAUSED ALBERTO
 TO MOVE SLOWLY WEST-SOUTHWESTWARD SINCE YESTERDAY...AND THE CURRENT
 MOTION IS 250/5 KT.  THE BLOCKING ANTICYCLONE CURRENTLY POSITIONED
 OVER WESTERN NEW ENGLAND IS EXPECTED TO BEGIN SLIDING EASTWARD
 TODAY WITH A PROGRESSIVE MID-LATITUDE TROUGH APPROACHING FROM THE
 UPPER MIDWEST.  ALBERTO SHOULD CONTINUE TO MOVE LITTLE THROUGH
 TONIGHT...BUT THE EVOLVING STEERING PATTERN IS EXPECTED TO
 ACCELERATE THE STORM NORTHEASTWARD BEGINNING ON MONDAY.  THERE IS
 VERY LITTLE SPREAD IN THE TRACK GUIDANCE THROUGH THE NEXT 48 HOURS.
 THEREAFTER...THE ECMWF DIVERGES FROM THE CLUSTER OF OTHER MODELS
 AND SHOWS A SLOWER...MORE SOUTHERN SOLUTION.  THE OFFICIAL FORECAST
 IS THEREFORE A LITTLE SLOWER AND FARTHER SOUTH THAN THE MULTI-MODEL
 CONSENSUS ON DAYS 3 AND 4.
   
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  20/1500Z 31.5N  79.7W   40 KT  45 MPH
  12H  21/0000Z 31.2N  79.7W   35 KT  40 MPH
  24H  21/1200Z 31.4N  79.1W   35 KT  40 MPH
  36H  22/0000Z 32.3N  77.6W   35 KT  40 MPH
  48H  22/1200Z 34.2N  75.4W   35 KT  40 MPH
  72H  23/1200Z 38.0N  70.5W   35 KT  40 MPH...POST-TROPICAL
  96H  24/1200Z 39.5N  66.5W   30 KT  35 MPH...POST-TROPICAL
 120H  25/1200Z...DISSIPATED
  
 $$
 FORECASTER BERG/PASCH