000
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