[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 312043
TCDAT2
HURRICANE EARL DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM AST TUE AUG 31 2010

ALTHOUGH THE SATELLITE PRESENTATION IS NOT AS IMPRESSIVE AS IT WAS
EARLIER...A RECONNAISSANCE PLANE AROUND 1700 UTC REPORTED A MINIMUM
PRESSURE OF 940 MB AND MAXIMUM FLIGHT-LEVEL WINDS OF 128 KNOTS.
THESE DATA SUPPORT AN INITIAL INTENSITY OF 115 KNOTS.
CURRENTLY...THERE IS SOME SOUTHWESTERLY SHEAR DISRUPTING THE
UPPER-LEVEL OUTFLOW OVER THE WESTERN SEMICIRCLE OF EARL.  THIS SHEAR
IS CAUSED BY A WEAK UPPER-LOW OR TROUGH OVER THE EASTERN BAHAMAS AS
OBSERVED ON WATER VAPOR IMAGES.  HOWEVER...MODELS WEAKEN THE UPPER
LOW AS EARL MOVES AROUND IT...RESULTING IN A MORE FAVORABLE
ENVIRONMENT. EARL IS EXPECTED TO MAINTAIN ITS CATEGORY FOUR
INTENSITY FOR THE NEXT DAY OR TWO.

EARL HAS BEGUN TO MOVE TOWARD THE NORTHWEST OR 305 DEGREES AT 12 OR
13 KNOTS DURING THE PAST FEW HOURS. THE SUBTROPICAL HIGH THAT IS
STEERING EARL TOWARD THE WEST-NORTHWEST OR NORTHWEST IS FORECAST TO
GRADUALLY SHIFT EASTWARD AS A BROAD TROUGH BECOMES ESTABLISHED OVER
THE EASTERN UNITED STATES. THIS PATTERN WILL FORCE EARL ON A MORE
NORTHWESTERLY AND NORTHERLY TRACK FOR THE NEXT DAY OR TWO.
THEREAFTER...EARL WILL REACH THE BASE OF THE MID-LATITUDE WESTERLIES
AND WILL LIKELY TURN SHARPLY TO THE NORTHEAST WITH AN INCREASE IN
FORWARD SPEED.  THIS IS THE SOLUTION UNANIMOUSLY PROVIDED BY TRACK
GUIDANCE.  ONCE AGAIN THE OFFICIAL FORECAST HAS BEEN SHIFTED A FEW
MILES TO THE WEST BEFORE 48 HOURS FOLLOWING THE TRENDS OF THE ECMWF
AND THE GFS.

GIVEN THE LARGE AREA OF TROPICAL STORM FORCE WINDS ASSOCIATED WITH
EARL...AND THE NEW DEFINITION OF WATCHES AND WARNINGS...A HURRICANE
AND TROPICAL STORM WATCH HAS BEEN ISSUED FOR A PORTION OF THE MID-
ATLANTIC COAST.

INTERESTS FROM VIRGINIA NORTHWARD TO NEW ENGLAND SHOULD MONITOR THE
PROGRESS OF EARL.

FORECAST POSITIONS AND MAX WINDS

INITIAL      31/2100Z 22.0N  68.8W   115 KT
 12HR VT     01/0600Z 23.3N  70.5W   115 KT
 24HR VT     01/1800Z 25.6N  72.8W   115 KT
 36HR VT     02/0600Z 28.0N  74.5W   115 KT
 48HR VT     02/1800Z 31.0N  75.5W   115 KT
 72HR VT     03/1800Z 36.0N  73.5W    95 KT
 96HR VT     04/1800Z 44.0N  65.0W    75 KT
120HR VT     05/1800Z 56.0N  55.0W    50 KT...POST-TROP/EXTRATROP

$$
FORECASTER AVILA



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