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HURRICANE EARL DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM EDT THU SEP 02 2010
 
DATA FROM A RECONNAISSANCE PLANE INDICATE THAT EARL HAS WEAKENED A
LITTLE BIT THIS AFTERNOON.  THE CENTRAL PRESSURE ROSE TO 947
MB...AND A BLEND OF THE SFMR MEASUREMENTS AND FLIGHT-LEVEL WINDS
SUGGEST THAT THE INITIAL INTENSITY HAS DECREASED TO 100 KNOTS. EARL
SHOULD CONTINUE TO WEAKEN GRADUALLY AS THE SHEAR INCREASES AND THE
HURRICANE SHOULD WEAKEN EVEN FASTER AFTER 24 HOURS AS IT MOVES OVER
A COLDER OCEAN.  AFTER CROSSING CANADA IN 48 HOURS...EARL SHOULD
BECOME POST-TROPICAL/EXTRATROPICAL AND THEN DISSIPATE AS IT IS
ABSORBED BY A MUCH LARGER EXTRATROPICAL CYCLONE.
 
SATELLITE AND RECONNAISSANCE FIXES SHOW...AS ANTICIPATED...THAT EARL
HAS TURNED NORTHWARD AND IS MOVING 360 DEGREES AT 16 KNOTS. THE
STEERING PATTERN CONTROLLING THE MOTION OF EARL...AND THE
CONSISTENCY IN TRACK GUIDANCE...HAVE BEEN ADEQUATELY DESCRIBED IN
PREVIOUS DISCUSSIONS. EARL IS ABOUT TO BECOME EMBEDDED IN THE
MID-LATITUDE FLOW AND IT IS READY TO GRADUALLY TURN TO THE
NORTH-NORTHEAST AND NORTHEAST WITH AN INCREASE IN FORWARD SPEED. 

ALTHOUGH THE MAXIMUM WINDS IN THE CORE HAVE DECREASED...EARL
CONTINUES TO BE A LARGE AND POWERFUL HURRICANE. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/2100Z 32.5N  75.2W   100 KT
 12HR VT     03/0600Z 34.8N  74.8W    95 KT
 24HR VT     03/1800Z 38.0N  72.7W    85 KT
 36HR VT     04/0600Z 41.7N  69.0W    75 KT
 48HR VT     04/1800Z 46.5N  64.5W    50 KT...POST-TROP/EXTRATROP
 72HR VT     05/1800Z...DISSIPATED
 
$$
FORECASTER AVILA
 
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TROPICAL STORM FIONA DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082010
500 PM AST THU SEP 02 2010
 
THERE HAS BEEN LITTLE CHANGE WITH FIONA DURING THE DAY. THE STORM
CONTINUES THE PATTERN OBSERVED DURING THE LAST DAY OR SO OF BURSTS
OF CONVECTION FORMING NEAR THE CENTER...THEN SHEARING AWAY. AN
ASCAT PASS FROM LATE THIS MORNING SHOWED MAXIMUM WINDS OF ABOUT 40
KT. GIVEN THE WELL-DOCUMENTED LOW BIAS OF THAT INSTRUMENT...45 KT
SEEMS LIKE A REASONABLE INITIAL WIND SPEED. THE INTENSITY FORECAST
IS DIFFICULT BECAUSE IT SEEMS LIKE FIONA HAS BEEN WITHSTANDING THE
SHEAR BETTER THAN MOST TROPICAL CYCLONES. THE LATEST INTENSITY
GUIDANCE DOES NOT WEAKEN THE STORM AS QUICKLY AS EARLIER...BUT IS
ACTUALLY PRETTY CLOSE TO THE PREVIOUS FORECAST. THUS NO CHANGES ARE
MADE TO THE LAST NHC FORECAST. AFTER 72 HOURS...ALL OF THE GLOBAL
MODELS SHOW THE TROPICAL CYCLONE SHEARING OUT AS IT MOVES
NORTHEASTWARD.
 
FIONA HAS TURNED A LITTLE MORE AND IS NOW MOVING 335/15.  THERE IS
NO CHANGE IN SYNOPTIC REASONING WITH THE CYCLONE MOVING AROUND A
SUBTROPICAL ANTICYCLONE.  THE STORM SHOULD TURN TOWARD THE NORTH...
THEN NORTHEAST AS IT STARTS TO MOVE INTO THE MID-LATITUDES. THE
MODELS ARE GENERALLY SLOWER THAN THE PREVIOUS CYCLE...BUT SINCE
THE CYCLONE CONTINUES SPEEDING ALONG...THE NHC FORECAST WILL STAY
ON THE FASTER SIDE OF THE GUIDANCE ENVELOPE...WITH LITTLE CHANGE TO
THE TRACK. THERE IS REASONABLE AGREEMENT THAT FIONA WILL BE CLOSE
TO BERMUDA IN 36-48 HOURS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/2100Z 25.6N  66.4W    45 KT
 12HR VT     03/0600Z 27.5N  66.8W    45 KT
 24HR VT     03/1800Z 29.7N  66.4W    45 KT
 36HR VT     04/0600Z 31.7N  65.4W    40 KT
 48HR VT     04/1800Z 33.7N  64.1W    35 KT
 72HR VT     05/1800Z 38.0N  61.0W    25 KT...DISSIPATING
 96HR VT     06/1800Z...DISSIPATED
 
$$
FORECASTER BLAKE/BROWN
 
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