000 WTNT41 KNHC 082038 TCDAT1 TROPICAL STORM IGOR DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 500 PM AST WED SEP 08 2010 MODERATE TO STRONG CONVECTION CONTINUES TO BE LOCATED TO THE WEST OF THE CENTER...A SYMPTOM OF EASTERLY SHEAR. HIGH-RESOLUTION ASCAT DATA EARLIER INDICATED PEAK WINDS OF 35-40 KT...AND WITH SATELLITE CLASSIFICATIONS INCREASING...THE WIND SPEED IS RAISED TO 40 KT. AN UNCERTAIN ESTIMATE OF THE INITIAL MOTION IS 275/5. THE MOTION HAS SLOWED SIGNIFICANTLY...POSSIBLY DUE TO THE LOW PRESSURE AREA APPROACHING THE NORTHERN CAPE VERDE ISLANDS. THE GLOBAL MODELS ARE SHOWING A DIFFERENT SCENARIO IN THE SHORT-TERM AND HAVE TRENDED TOWARD THE 00/12Z ECMWF SOLUTIONS. AS THE SMALL LOW TO THE NORTHEAST OF IGOR MOVES WESTWARD...THE RIDGE IS FORECAST TO WEAKEN SLIGHTLY...WHICH ALLOWS IGOR TO MOVE TO THE WEST-NORTHWEST OR EVEN NORTHWEST BRIEFLY. AFTERWARDS...THE RIDGE RESTRENGTHENS... WHICH SHOULD TURN IGOR WESTWARD AGAIN. THE NHC FORECAST IS SHIFTED TO THE NORTH TO ACCOUNT FOR THE INTERACTION OF THE TWO SYSTEMS AND THE NORTHWARD SHIFT IN THE MODELS...BUT STILL LIES ALONG THE SOUTHERN EDGE OF THE ENVELOPE. THE INTENSITY FORECAST...AT LEAST IN THE SHORT-TERM...SEEMS TRICKY WITH IGOR ONLY ABOUT 210 NM SOUTHWEST OF THE AFOREMENTIONED LOW. THERE CERTAINLY IS THE POTENTIAL FOR SOME SORT OF INTERACTION THAT COULD SLOW THE STRENGTHENING PROCESS. THUS THE INTENSITY FORECAST WILL ONLY SHOW SLOW INTENSIFICATION IN THE SHORT-TERM...GENERALLY A LITTLE LOWER THAN THE MODELS. IN THE LONGER-RANGE...THERE IS PLENTY OF WARM WATER AND LIGHT SHEAR FORECAST IN THE PATH OF IGOR...WHICH WOULD PROMOTE THE DEVELOPMENT OF A LARGE AND POWERFUL HURRICANE. THE NHC FORECAST IS INCREASED FROM THE PREVIOUS ONE...CLOSE TO THE CONSENSUS...AND STILL MIGHT BE CONSERVATIVE AT THE END. HOWEVER...WITH THE TRACK FORECAST SHIFTING NORTHWARD... I AM HESITANT TO FORECAST A MUCH STRONGER HURRICANE AT THIS TIME. FORECAST POSITIONS AND MAX WINDS INITIAL 08/2100Z 13.9N 23.9W 40 KT 12HR VT 09/0600Z 14.0N 24.8W 45 KT 24HR VT 09/1800Z 14.7N 26.5W 50 KT 36HR VT 10/0600Z 15.5N 29.1W 55 KT 48HR VT 10/1800Z 16.3N 32.2W 60 KT 72HR VT 11/1800Z 17.0N 37.5W 70 KT 96HR VT 12/1800Z 17.5N 42.5W 80 KT 120HR VT 13/1800Z 18.5N 47.5W 90 KT $$ FORECASTER BLAKE/PASCH