Hurricane DANIELLE

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HURRICANE DANIELLE DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED AUG 18 2004
 
DANIELLE IS EXPERIENCING SOME MODERATE SOUTHWESTERLY UPPER-LEVEL
SHEAR. A COMBINATION OF THE SHEAR AND SOME DRY AIR ALSO PUNCHING IN
FROM THE SOUTHWEST HAS RESULTED IN THE LOW-LEVEL CIRCULATION
BECOMING PARTLY EXPOSED NEAR THE SOUTHWESTERN EDGE OF THE
CONVECTIVE CLOUD SHIELD. HOWEVER...THE CIRCULATION IS STILL JUST
INSIDE THE CONVECTIVE CLOUD SHIELD...SO DANIELLE IS BEING
MAINTAINED AS A 65-KT HURRICANE. THE INITIAL INTENSITY OF 65 KT IS
CONSISTENT WITH A BLEND OF DVORAK T-NUMBERS OF T3.5...OR 55 KT...
AND CURRENT INTENSITY NUMBERS OF T4.5...OR 77 KT.
 
THE INITIAL MOTION IS 360/12. EVEN THOUGH DANIELLE HAS BECOME PARTLY
SHEARED...THE LOW-LEVEL CIRCULATION HAS BEEN KEEPING UP WITH THE
CONVECTIVE CLOUD SHIELD. THIS IS A TESTAMENT TO THE DEEP VERTICAL
CIRCULATION THAT THIS CYCLONE HAD WHEN IT CAME OFF WEST AFRICA
ALMOST A WEEK AGO. SINCE DANIELLE WILL REMAIN OVER 26C AND HIGHER
SSTS FOR THE NEXT 48 HOURS OR SO...INTERMITTENT CONVECTION SHOULD
CONTINUE TO BURST NEAR THE CENTER AND HELP TO KEEP THE VERTICAL
CIRCULATION INTACT. THIS SHOULD ALLOW THE CYCLONE TO GRADUALLY
ROUND THE TOP OF THE RIDGE LOCATED ALONG 30-32N LATITUDE...AND THEN
TURN NORTHEASTWARD AND ACCELERATE AFTER THAT AS THE A MID- TO
UPPER-LEVEL TROUGH GRADUALLY CAPTURES IT. THE FORECAST TRACK IS
SIMILAR TO THE PREVIOUS FORECAST AND IS CLOSE TO THE GUNS CONSENSUS
MODEL...SINCE THE GUNA CONSENSUS IS MUCH SLOWER AS A RESULT OF THE
GFS MODELING RAPIDLY WEAKENING DANIELLE AND KEEPING IT STATIONARY.

EVEN THOUGH DANIELLE HAS WEAKENED SIGNIFICANTLY IN THE PAST 6
HOURS...THE OCEAN IS EXPECTED TO REMAIN WARM ENOUGH TO SUPPORT
CONTINUED CONVECTIVE DEVELOPMENT FOR ABOUT THE NEXT 48 HOURS. AFTER
THAT...DANIELLE IS FORECAST TO BECOME ABSORBED BY AN APPROACHING
FRONTAL SYSTEM FROM THE NORTHWEST AND BE A GALE AREA AS IT MOVES
THROUGH THE AZORES ISLANDS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0900Z 27.9N  40.7W    65 KT
 12HR VT     18/1800Z 29.4N  40.5W    60 KT
 24HR VT     19/0600Z 31.3N  39.5W    55 KT
 36HR VT     19/1800Z 32.7N  38.4W    50 KT
 48HR VT     20/0600Z 33.8N  37.0W    50 KT
 72HR VT     21/0600Z 36.5N  32.5W    45 KT...BECOMING EXTRATROPICAL
 96HR VT     22/0600Z 40.0N  26.0W    40 KT...EXTRATROPICAL
120HR VT     23/0600Z 46.0N  16.0W    35 KT...EXTRATROPICAL
 
 
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