Tropical Storm EARL

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TROPICAL STORM EARL DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
1100 AM AST THU AUG 26 2010
 
VISIBLE AND MICROWAVE SATELLITE IMAGERY INDICATE EARL HAS NOT BECOME
ANY BETTER ORGANIZED SINCE THE LAST ADVISORY. IN FACT...THE INNER
CORE CONVECTION HAS ERODED DUE TO DRY AIR ENTRAINMENT NOTED IN
CONVENTIONAL WATER VAPOR IMAGERY AND IN A 0735Z SSMI WATER VAPOR
IMAGE. THE INITIAL INTENSITY WILL REMAIN 40 KT FOR THIS ADVISORY
BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES OF 45 KT AND 35
KT FROM TAFB AND SAB...RESPECTIVELY.
 
THE CENTER OF EARL HAS BEEN REPOSITIONED ABOUT 30 NMI SOUTH OF THE
PREVIOUS ADVISORY AND FORECAST TRACK BASED ON A BLEND OF VISIBLE
AND MICROWAVE FIXES. THE INITIAL MOTION ESTIMATE IS A 24-HOUR
AVERAGE OF 275/15...AFTER SMOOTHING THROUGH ALL THE WIGGLES AND
WOBBLES IN THE FIXES. THE OFFICIAL FORECAST TRACK WAS SHIFTED SOUTH
OF THE PREVIOUS ADVISORY DUE IN PART TO THE MORE SOUTHWARD INITIAL
POSITION. OTHERWISE...THERE REMAINS NO SIGNIFICANT CHANGE TO THE
PREVIOUS TRACK REASONING. EARL IS EXPECTED TO MOVE STEADILY WEST TO
WEST-NORTHWESTWARD FOR THE NEXT 72 HOURS AND THEN GRADUALLY TURN
NORTHWESTWARD AND SLOW DOWN AS THE CYCLONE APPROACHES A WEAKNESS IN
THE SUBTROPICAL RIDGE BETWEEN BERMUDA AND THE LEEWARD ISLANDS. THIS
WEAKNESS IN THE STEERING FLOW IS THE COMBINED EFFECTS OF HURRICANE
DANIELLE AND A MID-LATITUDE TROUGH FORECAST TO CAPTURE AND LIFT OUT
THAT HURRICANE TO THE NORTHEAST. IF DANIELLE RECURVES FASTER THAN
CURRENTLY EXPECTED...WHICH THE UKMET AND ECMWF ARE HINTING AT...
THEN THE RIDGE TO THE NORTH OF EARL COULD BUILD BACK IN SOONER AND
KEEP EARL ON A SLOWER WEST-NORTHWESTWARD TRACK THAN INDICATED BY
THE OFFICIAL FORECAST TRACK. THE ADVISORY TRACK LIES ALONG THE
NORTHERN EDGE OF THE TIGHTLY PACKED MODEL GUIDANCE SUITE AND
SIMILAR TO THE SPEED OF THE CONSENSUS MODEL...TVCN.
 
ALL OF THE MODELS INDICATE THAT THE VERTICAL SHEAR SHOULD REMAIN
QUITE LOW THROUGH 72 HOURS OR SO...WHICH WOULD FAVOR SIGNIFICANT
INTENSIFICATION. HOWEVER...THE DRY MID-LEVEL ENVIRONMENT THAT EARL
IS FORECAST TO MOVE THROUGH DURING THAT TIME IS EXPECTED TO RESULT
IN A SLOWER THAN NORMAL RATE OF INTENSIFICATION. HOWEVER...BY DAYS
4 AND 5...EARL IS FORECAST TO MOVE INTO THE SOUTHWESTERLY PERIPHERY
OF SYNOPTIC-SCALE 200 MB ANTICYCLONE...WHICH GENERALLY FAVORS
DEVELOPMENT DUE TO ENHANCED OUTFLOW TO THE NORTH AND SOUTH OF THE
CYCLONE. IT IS POSSIBLE THAT EARL COULD REACH MAJOR HURRICANE
STRENGTH BY THAT TIME...AS INDICATED BY THE HWRF MODEL. THE
OFFICIAL INTENSITY FORECAST IS A BLEND OF THE VARIOUS INTENSITY
MODELS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/1500Z 14.9N  37.1W    40 KT
 12HR VT     27/0000Z 15.4N  39.4W    45 KT
 24HR VT     27/1200Z 15.7N  42.6W    50 KT
 36HR VT     28/0000Z 16.1N  46.0W    55 KT
 48HR VT     28/1200Z 16.5N  49.1W    65 KT
 72HR VT     29/1200Z 17.8N  54.4W    75 KT
 96HR VT     30/1200Z 20.0N  58.5W    85 KT
120HR VT     31/1200Z 22.5N  61.0W    95 KT
 
$$
FORECASTER STEWART
 
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