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 309 
 WTNT42 KNHC 080301
 TCDAT2
 TROPICAL STORM FRED DISCUSSION NUMBER   2
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072009
 1100 PM AST MON SEP 07 2009
  
 A RECENTLY RECEIVED TRMM PASS FROM 2324 UTC SUGGESTS THAT THE CENTER
 OF THE CYCLONE IS LOCATED FARTHER SOUTH AND CLOSER TO THE DEEP
 CONVECTION. RECENT INFRARED GEOSTATIONARY IMAGERY SHOWS A CURVED
 BAND BEGINNING TO WRAP INTO THE LOCATION OF THE SUSPECTED CENTER.
 BASED ON THIS EVIDENCE...THE DEPRESSION IS UPGRADED TO TROPICAL
 STORM FRED AND THE INITIAL INTENSITY IS SET TO 35 KT. THE SHIPS
 MODEL CURRENTLY ANALYZES EASTERLY WIND SHEAR OF ABOUT 15 KNOTS OVER
 FRED. THIS SHEAR IS FORECAST TO DECREASE IN ABOUT 12 HOURS...AND
 WITH THE CYCLONE MOVING OVER WARM WATER...THIS SHOULD ALLOW FOR
 ADDITIONAL STRENGTHENING THROUGH 72 HOURS OR SO. BEYOND THAT
 TIME...FRED IS EXPECTED TO ENCOUNTER INCREASINGLY SOUTHWESTERLY
 WIND SHEAR AHEAD OF AN UPPER-LEVEL TROUGH. THE COMBINATION OF THE
 SHEAR AND COOLER SSTS SHOULD RESULT IN A SLOW WEAKENING AT DAYS 4
 AND 5. THE OFFICIAL FORECAST IS ABOVE THE ICON INTENSITY CONSENSUS
 FOR THE FIRST 24 HOURS GIVEN THE CURRENT SATELLITE TRENDS...AND IS
 CLOSE TO ICON FROM 24 TO 48 HOURS. BEYOND THAT TIME...THE INTENSITY
 FORECAST IS CLOSER TO LGEM...SINCE THAT MODEL TYPICALLY HAS A GOOD
 HANDLE ON THE EFFECTS OF CHANGING ENVIRONMENTAL CONDITIONS LATE IN
 THE FORECAST PERIOD.
  
 THE INITIAL MOTION IS ESTIMATED TO BE 275/13...BUT THIS IS UNCERTAIN
 GIVEN THE RECENT RELOCATION OF THE CENTER. THE TRACK GUIDANCE
 REMAINS IN GENERAL AGREEMENT ON TAKING THE CYCLONE ON A WESTWARD TO
 WEST-NORTHWESTWARD HEADING TO THE SOUTH OF A NARROW SUBTROPICAL
 RIDGE AXIS FOR ABOUT 48 HOURS. BEYOND THAT TIME...FRED IS EXPECTED
 TO RECURVE INTO A BREAK IN THE RIDGE BETWEEN 30W AND 35W. AT THE
 END OF THE PERIOD...MUCH OF THE GUIDANCE SUGGESTS A VERY SLOW
 NORTHWARD OR NORTH-NORTHWESTWARD MOTION...AS THE MID-TO UPPER-LEVEL
 TROUGH THAT CAUSES THE BREAK IN THE RIDGE LIFTS OUT...ALLOWING WEAK
 RIDGING TO BUILD IN NORTH OF FRED. THE OFFICIAL FORECAST TRACK IS
 SHIFTED SIGNIFICANTLY TO THE SOUTH OF THE PREVIOUS TRACK DUE TO THE
 MORE SOUTHERLY LOCATION OF THE CENTER. BY THE END OF THE
 PERIOD...THE OFFICIAL FORECAST SHOWS A TURN TOWARD THE NORTH AND
 THE NORTH-NORTHWEST WITH A DECREASE IN FORWARD SPEED...IN GOOD
 AGREEMENT WITH THE TVCN MULTI-MODEL CONSENSUS.
 
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      08/0300Z 11.8N  26.3W    35 KT
  12HR VT     08/1200Z 12.0N  28.0W    45 KT
  24HR VT     09/0000Z 12.6N  30.0W    50 KT
  36HR VT     09/1200Z 13.6N  31.7W    55 KT
  48HR VT     10/0000Z 14.8N  32.9W    60 KT
  72HR VT     11/0000Z 17.5N  34.0W    55 KT
  96HR VT     12/0000Z 19.0N  34.0W    55 KT
 120HR VT     13/0000Z 21.0N  34.5W    50 KT
  
 $$
 FORECASTER BRENNAN
  
 
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