Hurricane IGOR

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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
 
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