768 
 WTNT41 KNHC 081459
 TCDAT1
 TROPICAL STORM IGOR DISCUSSION NUMBER   1
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112010
 1100 AM AST WED SEP 08 2010
  
 THE LOW OVER THE FAR EASTERN TROPICAL ATLANTIC OCEAN HAS BECOME
 BETTER DEFINED AND DEEP CONVECTION NEAR THE CENTER HAS PERSISTED
 LONG ENOUGH FOR THIS SYSTEM TO BE CONSIDERED A TROPICAL CYCLONE. A
 1042 UTC ASCAT PASS SHOWED WINDS OF 35 KT...AND THE INITIAL
 INTENSITY WILL BE SET TO THAT VALUE.  EASTERLY SHEAR IS PRESENT
 OVER IGOR...BUT IS FORECAST TO LIGHTEN IN A DAY OR SO.  ALL
 RELIABLE MODELS SHOW INTENSIFICATION INTO A HURRICANE IN THE NEXT
 SEVERAL DAYS.  BECAUSE OF THE SHEAR...THE NHC INTENSITY FORECAST
 WILL ONLY SHOW RELATIVELY SLOW STRENGTHENING...BELOW THE GUIDANCE
 INITIALLY...BUT THE FORECAST ENDS UP CLOSE TO THE CONSENSUS AT DAY
 5.  IF THE UPPER ANTICYCLONE PATTERN SEEN IN MOST OF THE GLOBAL
 MODELS VERIFY...THE OFFICIAL FORECAST COULD BE CONSERVATIVE IN THE
 LATTER PART OF THE FORECAST PERIOD.
  
 THE INITIAL MOTION IS 265/7.  A MID-LEVEL RIDGE OVER THE EASTERN
 ATLANTIC OCEAN IS FORECAST TO STRENGTHEN OVER THE NEXT FEW
 DAYS...WHICH SHOULD CAUSE A WESTWARD MOTION AT AN INCREASING
 FORWARD SPEED.  AT THE END OF THE PERIOD...A TROUGH OVER THE
 CENTRAL ATLANTIC COULD WEAKEN THE RIDGE...FORCING THE STORM TO MOVE
 MORE TO THE WEST-NORTHWEST.  THE MODEL GUIDANCE IS IN RELATIVELY
 GOOD AGREEMENT ON THIS SCENARIO...ALTHOUGH THERE IS SOME SHORT-TERM
 UNCERTAINTY ON HOW IGOR WILL INTERACT WITH THE LARGE CONVECTIVE
 SYSTEM TO THE NORTHEAST OF THE STORM. THE NHC FORECAST IS NEAR OR
 SLIGHTLY SOUTH OF THE MODEL CONSENSUS.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      08/1500Z 13.7N  23.5W    35 KT
  12HR VT     09/0000Z 13.7N  24.6W    40 KT
  24HR VT     09/1200Z 13.8N  26.6W    45 KT
  36HR VT     10/0000Z 14.0N  29.0W    50 KT
  48HR VT     10/1200Z 14.5N  31.5W    55 KT
  72HR VT     11/1200Z 15.5N  36.5W    65 KT
  96HR VT     12/1200Z 16.8N  41.2W    75 KT
 120HR VT     13/1200Z 18.0N  46.0W    85 KT
  
 $$
 FORECASTER BLAKE/PASCH