000 WTNT41 KNHC 110835 TCDAT1 TROPICAL STORM IGOR DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 500 AM AST SAT SEP 11 2010 IGOR IS STRENGTHENING AND IN FACT...THERE WAS A PERIOD FOR ABOUT TWO HOURS...BETWEEN 04 AND 06 UTC THAT A SMALL EYE-LIKE FEATURE BECAME APPARENT ON SATELLITE. HOWEVER...SINCE THEN...SUCH FEATURE HAS BECOME INTERMITTENT...OTHERWISE I COULD HAVE DECLARED IGOR A HURRICANE. ALTHOUGH THE CLOUD PATTERN IS BETTER ORGANIZED...THE OVERALL CONVECTION HAS DECREASED A LITTLE AND NOW CONSISTS OF TWO WELL-DEFINED CYCLONICALLY CURVED BANDS LOCATED PRIMARILY TO THE SOUTH OF THE CENTER. THE OUTFLOW HAS BECOME ESTABLISHED IN ALL QUADRANTS. BASED ON A BLEND OF T-NUMBERS FROM TAFB AND SAB WHICH ARE 4.0 AND 3.5 ON THE DVORAK SCALE...THE INITIAL INTENSITY HAS BEEN INCREASED TO 60 KNOTS. GIVEN THE CURRENT INTENSITY TREND...THE CYCLONE WILL LIKELY BECOME A HURRICANE LATER TODAY. ALL OF THE ENVIRONMENTAL PARAMETERS APPEAR TO BE FAVORABLE FOR IGOR TO INTENSIFY...AND THE FORECAST CALLS FOR IGOR TO BE AN INTENSE HURRICANE IN ABOUT 3 DAYS. GLOBAL MODELS SUGGEST THAT IGOR COULD ALSO BECOME LARGE. IGOR IS MOVING TOWARD TOWARD THE WEST OR 270 DEGREES AT 18 KNOTS. THIS IS BASED ON THE MOTION OF THE EYE-LIKE FEATURE AND CONTINUITY. THE CYCLONE IS BEING STEERED BY A BUILDING SUBTROPICAL RIDGE OVER THE EASTERN ATLANTIC...AND THIS PATTERN IS FORECAST BY GLOBAL MODELS TO PERSIST. ON THIS BASIS...THE OFFICIAL FORECAST CALLS FOR A GENERAL WESTWARD MOTION FOR THE NEXT 3 DAYS OR SO. BY THEN...IGOR WILL BE REACHING THE SOUTHWESTERN EDGE OF THE SUBTROPICAL HIGH WHERE THE STEERING CURRENTS ARE WEAKER...AND BEGIN TO APPROACH A BROAD TROUGH OVER THE WESTERN ATLANTIC. THIS PATTERN SHOULD FORCE IGOR TO SLOW DOWN AND BEGIN TO TURN MORE TO THE WEST-NORTHWEST AND NORTHWEST. THE TRACK FORECAST IS VERY CLOSE TO THE CONSENSUS AND BIASED TO THE ECMWF AND THE GFS. FORECAST POSITIONS AND MAX WINDS INITIAL 11/0900Z 17.1N 37.8W 60 KT 12HR VT 11/1800Z 17.1N 40.2W 70 KT 24HR VT 12/0600Z 17.2N 43.1W 75 KT 36HR VT 12/1800Z 17.4N 46.0W 80 KT 48HR VT 13/0600Z 17.5N 48.5W 90 KT 72HR VT 14/0600Z 17.5N 52.5W 100 KT 96HR VT 15/0600Z 18.5N 55.5W 100 KT 120HR VT 16/0600Z 20.5N 59.0W 100 KT $$ FORECASTER AVILA