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| #376402 (Received by flhurricane at: 4:59 AM 16.Sep.2010) TCDAT1 HURRICANE IGOR DISCUSSION NUMBER 33 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 500 AM AST THU SEP 16 2010 MICROWAVE AND INFRARED SATELLITE IMAGERY SUGGEST THAT THE EYEWALL REPLACEMENT WITH IGOR IS COMPLETE. THE NEW EYEWALL APPEARS TO BE CONSOLIDATING AT A RADIUS OF ABOUT 30-35 N MI AND IS PRODUCING RATHER DEEP CONVECTION...SUGGESTING THE INTENSITY IS INCREASING AGAIN. A BLEND OF THE SATELLITE ESTIMATES GIVES AN INITIAL INTENSITY OF 125 KT. A LARGE-SCALE ENVIRONMENT OF LIGHT SHEAR AND WARM WATER IS FAVORABLE FOR THE MAINTENANCE OF AN EXTREMELY DANGEROUS HURRICANE FOR THE NEXT FEW DAYS. THE EXACT INTENSITY OF IGOR WILL BE PRIMARILY DICTATED BY EYEWALL CYCLES...WHICH ARE WELL BEYOND OUR FORECAST ABILITIES. THE MAJORITY OF THE MODEL GUIDANCE INDICATES THAT SLOW WEAKENING IS THE MOST LIKELY SOLUTION...AND THE NHC FORECAST REFLECT THIS. HOWEVER...IT IS MORE IMPORTANT TO RECOGNIZE THAT ALL OF THE GUIDANCE...AND THE NHC FORECAST...KEEPS IGOR AS A LARGE AND DANGEROUS HURRICANE FOR THE NEXT SEVERAL DAYS. THE INITIAL MOTION IS AN UNSTEADY 300/6. IGOR IS EXPECTED TO MOVE SLOWLY AROUND THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC. WEAK TROUGHING ALONG ABOUT 70W SHOULD RECURVE THE CYCLONE IN 3 OR 4 DAYS. THE MAIN DIFFERENCE IN THE MODELS IS HOW QUICKLY IGOR ACCELERATES TO THE NORTHEAST IN THE MID-LATITUDES. SINCE THE TROUGHING OVER THE WESTERN ATLANTIC IS RATHER FLAT... THERE HAS BEEN A TREND IN THE MODELS TO SHOW WEAKER FLOW NEAR IGOR...AND CONSEQUENTLY DELAY THE INCREASE IN FORWARD SPEED. THE OFFICIAL FORECAST IS A BIT SLOWER THAN THE PREVIOUS ONE... ESPECIALLY AT THE END OF THE PERIOD. WITH REGARDS TO HOW CLOSE IGOR COMES TO BERMUDA...THE ECMWF IS NOW THE MOST EASTERN MODEL AFTER BEING THE WESTERNMOST YESTERDAY. THIS APPEARS TO BE DUE TO THAT MODEL SHOWING A SLIGHTLY WEAKER RIDGE TODAY...WHICH ALLOWS IGOR TO GAIN A LITTLE MORE LATITUDE EARLY ON AND EVENTUALLY PASS A LITTLE FARTHER EAST OF BERMUDA. HOWEVER...ALL OF THE GUIDANCE IS WELL CLUSTERED ON A TRACK CLOSE TO THAT ISLAND...AND LITTLE CHANGE HAS BEEN MADE TO THE OFFICIAL TRACK NEAR BERMUDA. SINCE THIS IS SUCH A LARGE HURRICANE...SIGNIFICANT IMPACTS ARE EXPECTED ON BERMUDA...BUT IT IS TOO EARLY TO TELL HOW CLOSE THE CORE OF THE HURRICANE...AND THE STRONGEST WINDS...WILL COME TO THAT ISLAND. SO FAR...NOAA BUOY 41044 HAS REPORTED A PEAK 1-MINUTE WIND OF 45 KT...GUSTING TO 56 KT...ALONG WITH A MINIMUM PRESSURE OF 995 MB...AND A SIGNIFICANT WAVE HEIGHT OF 29 FT. HOWEVER...THE WORST IS YET TO COME FOR THAT STATION...AS IGOR WILL MOVE VERY CLOSE TO THE BUOY TONIGHT. FORECAST POSITIONS AND MAX WINDS INITIAL 16/0900Z 20.5N 56.8W 125 KT 12HR VT 16/1800Z 21.1N 57.8W 125 KT 24HR VT 17/0600Z 22.0N 59.4W 125 KT 36HR VT 17/1800Z 23.2N 61.1W 120 KT 48HR VT 18/0600Z 24.7N 62.7W 120 KT 72HR VT 19/0600Z 28.0N 65.0W 110 KT 96HR VT 20/0600Z 32.5N 64.5W 95 KT 120HR VT 21/0600Z 37.5N 59.0W 80 KT $$ FORECASTER BLAKE |
