Hurricane EARL

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HURRICANE EARL DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM AST MON AUG 30 2010
 
THE RECONNAISSANCE AIRCRAFT MEASURED 116 KT FLIGHT-LEVEL WINDS AND
108 KT SFMR SURFACE WINDS SHORTLY AFTER 1500 UTC.  THIS WAS THE
BASIS FOR THE EARLIER INCREASE IN INTENSITY.  SINCE THAT TIME...THE
PRESSURE HAS CONTINUED TO DROP AND WAS DOWN TO 955 MB ON THE LAST
DROPSONDE RELEASED IN THE EYE AROUND 1700 UTC.  SINCE THE AIRCRAFT
DEPARTED EARL...THE EYE HAS CONTINUED TO CLEAR AND IS SURROUNDED BY
CLOUD TOPS TO -70 DEGREES CELSIUS OR COLDER.  OBJECTIVE SATELLITE
INTENSITY ESTIMATES HAVE INCREASED TO JUST ABOVE 6.0 ON THE DVORAK
SCALE AND SUPPORT AN INITIAL INTENSITY OF 115 KT...CATEGORY FOUR ON
THE SAFFIR-SIMPSON HURRICANE WIND SCALE.
 
EARL IS EXPECTED TO REMAIN IN A LOW SHEAR ENVIRONMENT AND OVER WARM
WATER DURING THE NEXT FEW DAYS AND SOME ADDITIONAL STRENGTHENING IS
LIKELY IN THE SHORT TERM.  THEREAFTER...EYEWALL CYCLES WILL LIKELY
INDUCE SOME FLUCTUATIONS IN INTENSITY...WHICH ARE DIFFICULT TO
PREDICT.  THE NHC FORECAST IS AGAIN NEAR THE HIGH END OF THE
INTENSITY GUIDANCE. AT DAYS 4 AND 5...THE HURRICANE IS FORECAST TO
MOVE OVER COOLER WATER AND INTO AN AREA OF INCREASING SHEAR WHICH
SHOULD RESULT IN WEAKENING.
 
THE INITIAL MOTION IS 290/13.  THE FORECAST REASONING REMAINS
UNCHANGED AS EARL IS EXPECTED TO TURN NORTHWESTWARD IN ABOUT 24
HOURS AROUND THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE. THE
TRACK GUIDANCE HAS SHIFTED NOTICEABLY WESTWARD DURING THE FIRST
48 HOURS...WITH THE GFS AND ECMWF ON THE EASTERN EDGE OF THE
ENVELOPE.  THE OFFICIAL FORECAST HAS BEEN ADJUSTED WESTWARD...
PRIMARILY THROUGH 72 HOURS...AND LIES BETWEEN THE GFS/ECMWF AND THE
MULTI-MODEL CONSENSUS.
  
THIS IS A GOOD TIME TO REMIND EVERYONE THAT NHC AVERAGE TRACK
FORECAST ERRORS ARE 200 TO 300 MILES AT DAYS 4 AND 5.  GIVEN THIS
UNCERTAINTY...IT IS TOO SOON TO DETERMINE WHAT PORTION OF THE U.S.
EAST COAST MIGHT SEE DIRECT IMPACTS FROM EARL.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/2100Z 19.3N  64.7W   115 KT
 12HR VT     31/0600Z 20.2N  66.3W   125 KT
 24HR VT     31/1800Z 21.7N  68.1W   130 KT
 36HR VT     01/0600Z 23.4N  70.1W   130 KT
 48HR VT     01/1800Z 25.8N  72.1W   125 KT
 72HR VT     02/1800Z 31.6N  74.7W   115 KT
 96HR VT     03/1800Z 38.0N  71.0W    95 KT
120HR VT     04/1800Z 45.5N  63.0W    70 KT...INLAND
 
$$
FORECASTER BROWN
 
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