[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 300236
TCDAT2
HURRICANE EARL DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
1100 PM AST SUN AUG 29 2010

EARL HAS STRENGTHENED OVER THE PAST FEW HOURS.  THE AIR FORCE
HURRICANE HUNTERS RECENTLY FOUND AN SFMR-MEASURED SURFACE WIND
SPEED OF 83 KT JUST SOUTHEAST OF THE CENTER.  MAXIMUM FLIGHT-LEVEL
WINDS FROM THE AIRCRAFT WERE 93 KT...WHICH ADJUSTS TO 84 KT AT THE
SURFACE USING THE STANDARD REDUCTION FACTOR.  BASED ON THESE
OBSERVATIONS...THE CURRENT INTENSITY IS SET TO 85 KT.  IMAGES FROM
THE GUADELOUPE AND ST. MARTIN RADARS SHOW A BANDING-TYPE EYE ABOUT
30 N MI IN DIAMETER WHILE THE RECONNAISSANCE OBSERVATIONS INDICATED
THAT THE EYE WAS OPEN OVER THE NORTHWEST QUADRANT.  WATER VAPOR
IMAGERY SHOWS THAT THE UPPER-LEVEL OUTFLOW IS BEING IMPEDED OVER
THE NORTHEAST QUADRANT...BUT IS WELL ESTABLISHED OVER THE REMAINDER
OF THE CIRCULATION.  A BROAD UPPER-LEVEL TROUGH IS CURRENTLY
SITUATED TO THE NORTHWEST OF EARL.  GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT THIS TROUGH WILL SHIFT WESTWARD AND WEAKEN.  THIS
SHOULD CREATE A ENVIRONMENT CONDUCIVE FOR INTENSIFICATION AND THE
OFFICIAL FORECAST...LIKE THE PREVIOUS ONE...SHOWS EARL BECOMING A
MAJOR HURRICANE OVER THE NEXT DAY OR SO.  THE NHC WIND SPEED
FORECAST IS ABOVE THE INTENSITY MODEL CONSENSUS BUT BELOW THE
LATEST GFDL HURRICANE MODEL GUIDANCE.

INITIAL MOTION...285/13...IS ABOUT THE SAME AS IN THE PREVIOUS
ADVISORY.  A GRADUAL TURN TO THE NORTHWEST IS LIKELY TO TAKE PLACE
IN 24 TO 36 HOURS AS THE HURRICANE ENCOUNTERS THE WESTERN PERIPHERY
OF A MID-TROPOSPHERIC ANTICYCLONE.  BY DAYS 3 TO 4...THE HEADING
AND FORWARD SPEED OF EARL ARE DEPENDENT ON THE DETAILS OF THE
EVOLUTION OF A 500 MB TROUGH MOVING THROUGH THE GREAT LAKES.  THE
GFS AND ECMWF SHOW THIS TROUGH AMPLIFYING MORE THAN THE OTHER
DYNAMICAL MODELS AND MOVE EARL SIGNIFICANTLY FASTER TO THE
NORTH-NORTHEAST WITH A SHARPER EASTWARD TURN THAN THE OTHER
GUIDANCE.  THE OFFICIAL TRACK FORECAST IS NOT QUITE AS FAST AS THE
GFS AND ECMWF...BUT IS CLOSE TO THE MULTI-MODEL CONSENSUS.

THE FORECAST WIND RADII HAVE BEEN EXPANDED A LITTLE BASED ON
DYNAMICAL...MAINLY GLOBAL MODEL...GUIDANCE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      30/0300Z 17.9N  61.1W    85 KT
 12HR VT     30/1200Z 18.5N  62.7W    90 KT
 24HR VT     31/0000Z 19.6N  64.6W   100 KT
 36HR VT     31/1200Z 21.1N  66.4W   110 KT
 48HR VT     01/0000Z 22.8N  68.2W   115 KT
 72HR VT     02/0000Z 27.5N  71.5W   115 KT
 96HR VT     03/0000Z 34.0N  72.0W   100 KT
120HR VT     04/0000Z 40.0N  67.0W    85 KT

$$
FORECASTER PASCH



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