Hurricane DANIELLE

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HURRICANE DANIELLE DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
1100 AM AST TUE AUG 24 2010
 
THE PERIOD OF RAPID INTENSIFICATION HAS ENDED WITH A THUD.  THE
LOW-LEVEL CENTER OF DANIELLE HAS BECOME EXPOSED BETWEEN A RAGGED
CENTRAL DENSE OVERCAST TO ITS EAST...AND A BROKEN CONVECTIVE BAND
TO ITS WEST.  ALL ALONG...MICROWAVE IMAGERY SINCE ABOUT 0300 UTC
SHOWED A DRY SLOT WRAPPING AROUND THE WESTERN AND SOUTHERN SIDE OF
THE CIRCULATION...AND AS A RESULT THE EYEWALL BECAME ERODED.  DATA
T-NUMBERS HAVE FALLEN QUICKLY AND ARE NOW AS LOW AS T3.9 FROM THE
HURRICANE INTENSITY ESTIMATE...AN EXPERIMENTAL FORM OF THE UW-CIMSS
ADT.  THE INITIAL INTENSITY IS LOWERED TO 70 KT AT THIS TIME...
WHICH COULD STILL BE GENEROUS.  SHIPS GUIDANCE SHOWS WESTERLY TO
SOUTHWESTERLY SHEAR INCREASING TO BETWEEN 15 AND 20 KT OVER THE
NEXT 24 HOURS OR SO...AND IT IS UNCLEAR HOW WELL DANIELLE WILL BE
ABLE TO MIX OUT THE DRY AIR.  ONLY SLOW STRENGTHENING IS INDICATED
IN THE OFFICIAL FORECAST...AND THE INTENSITY AT DAYS 4 AND 5 IS
HELD JUST BELOW MAJOR HURRICANE STRENGTH TO MAINTAIN SOME SORT OF
CONTINUITY...BUT THIS IS NOW ABOVE MANY OF THE INTENSITY MODELS.

MICROWAVE FIXES INDICATE THAT DANIELLE HAS BEEN MOVING QUICKLY WITH 
AND A AN INITIAL MOTION ESTIMATE OF 290/17.  THIS MOTION IS A
LITTLE TO THE LEFT OF THE FORECAST TRACK.  LITTLE CHANGE IS
REQUIRED IN THE FORECAST...AND DANIELLE IS STILL EXPECTED TO TURN
TOWARD THE NORTHWEST THROUGH A WEAKNESS IN THE SUBTROPICAL RIDGE.
THE MODEL GUIDANCE REMAINS IN VERY GOOD AGREEMENT ON THIS SCENARIO. 
THE OFFICIAL FORECAST TRACK LIES A LITTLE WEST OF THE PREVIOUS
FORECAST DURING THE NEXT 48 HOURS TO ACCOUNT FOR THE INITIAL MOTION
BUT THEN REMAINS CONSISTENT WITH THE EARLIER FORECASTS FOR DAYS 3
THROUGH 5.  THIS SOLUTION IS VERY CLOSE TO THE MULTI-MODEL
CONSENSUS TVCN AND STILL A LITTLE LEFT OF THE GFS...GFDL...AND
HWRF...WHICH SEAMS REASONABLE GIVEN THE CONTINUED LEFT-OF-TRACK
MOTION.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/1500Z 16.6N  46.5W    70 KT
 12HR VT     25/0000Z 17.5N  48.3W    75 KT
 24HR VT     25/1200Z 19.1N  50.4W    80 KT
 36HR VT     26/0000Z 21.0N  52.3W    85 KT
 48HR VT     26/1200Z 22.8N  53.8W    90 KT
 72HR VT     27/1200Z 26.0N  56.5W    90 KT
 96HR VT     28/1200Z 28.5N  58.5W    95 KT
120HR VT     29/1200Z 32.0N  59.5W    95 KT
 
$$
FORECASTER BERG
 
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