000 WTNT41 KNHC 090257 TCDAT1 TROPICAL STORM IGOR DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 1100 PM AST WED SEP 08 2010 IGOR REMAINS A SHEARED TROPICAL CYCLONE. THE MAIN CONVECTIVE CLOUD MASS IS DISPLACED WEST OF THE PARTIALLY EXPOSED LOW-LEVEL CENTER... AND THERE IS A SHARP EASTERN EDGE TO THE CENTRAL CONVECTION. IN ADDITION...THE CLOUD PATTERN HAS BECOME SOMEWHAT LESS ORGANIZED DURING THE PAST SEVERAL HOURS...WITH CLOUD TOP TEMPERATURES RECENTLY WARMING. DVORAK INTENSITY ESTIMATES ARE AT 2.5 FROM TAFB...AND THE 3-HOURLY AVERAGED ADT VALUE IS CLOSE TO 3.0. THE INITIAL INTENSITY ESTIMATE REPRESENTS A BLEND OF CURRENT INTENSITY ESTIMATES AND IS UNCHANGED AT 40 KT. THE COMBINATION OF MODERATE TO STRONG EASTERLY VERTICAL WIND SHEAR AND THE ONGOING INTERACTION OF IGOR WITH ANOTHER LOW LOCATED 150 N MI TO ITS NORTH IS EXPECTED TO IMPEDE THE INTENSIFICATION OF THE CYCLONE DURING THE NEXT DAY OR SO. BEYOND THAT TIME...THE CONSOLIDATION OF IGOR WITH THIS FEATURE...AS WELL AS A REDUCTION IN THE EASTERLY SHEAR...SHOULD RESULT IN A STEADY STRENGTHENING. THE NHC INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS CLOSE TO THE LGEM/SHIPS STATISTICAL-DYNAMICAL INTENSITY GUIDANCE. THE INITIAL MOTION ESTIMATE IS 270/06. THE FORECAST PHILOSOPHY REMAINS UNCHANGED. IN THE SHORT-TERM...GLOBAL MODELS SHOW IGOR INTERACTING WITH AND ABSORBING THE AFOREMENTIONED LOW DURING THE NEXT 24 HOURS. THIS SHOULD RESULT IN A SLIGHTLY WEAKER SUBTROPICAL RIDGE TO ITS NORTH AND TEMPORARILY IMPART A WEST-NORTHWESTWARD MOTION. FROM 24-96 HOURS...A RE-STRENGTHENING OF THE RIDGE IS FORECAST TO CAUSE IGOR TO TURN MORE WESTWARD. AFTER 96 HOURS...IGOR IS EXPECTED TO ENCOUNTER A DEVELOPING WEAKNESS IN THE SUBTROPICAL RIDGE AND TURN WEST-NORTHWESTWARD...SIMILAR TO BUT NOT AS FAR NORTH AS THE GFDL/HWRF SOLUTIONS. THE NHC OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ONE IN THE SHORT-TERM...BUT HAS BEEN ADJUSTED SLIGHTLY NORTHWARD IN LINE WITH THE MULTI-MODEL CONSENSUS AT LATER FORECAST PERIODS. FORECAST POSITIONS AND MAX WINDS INITIAL 09/0300Z 13.8N 24.6W 40 KT 12HR VT 09/1200Z 14.3N 25.7W 45 KT 24HR VT 10/0000Z 15.1N 27.9W 50 KT 36HR VT 10/1200Z 15.8N 30.7W 55 KT 48HR VT 11/0000Z 16.4N 33.6W 60 KT 72HR VT 12/0000Z 17.0N 39.0W 75 KT 96HR VT 13/0000Z 18.0N 43.5W 85 KT 120HR VT 14/0000Z 19.5N 47.5W 90 KT $$ FORECASTER KIMBERLAIN/STEWART