[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 290248
TCDAT1
HURRICANE DANIELLE DISCUSSION NUMBER  31
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
1100 PM AST SAT AUG 28 2010

CONVECTION IN THE OUTER EYEWALL OF DANIELLE HAS BECOME DEEPER DURING
THE PAST SEVERAL HOURS...WITH AN OCCASIONAL CELL EVEN FIRING NEAR
THE DECAYED INNER EYEWALL.  SATELLITE CLASSIFICATIONS ARE THE
BASICALLY THE SAME AS BEFORE...SO THE INITIAL INTENSITY REMAINS 90
KT.  A SLOW WEAKENING IS EXPECTED AS THE CYCLONE MOVES OVER COOLER
WATERS AND INCREASING SOUTHWESTERLY SHEAR.  MOST OF THE GLOBAL
MODELS SHOW DANIELLE BECOMING A LARGE AND POWERFUL EXTRATROPICAL
HURRICANE OVER THE NORTH ATLANTIC...AND THE NHC INTENSITY FORECAST
IS BASICALLY AN UPDATE OF THE PREVIOUS ONE.  IT IS POSSIBLE THAT
EXTRATROPICAL TRANSITION COULD BEGIN SOONER THAN SHOWN BELOW...AS
SUGGESTED BY A FEW MODELS.

THE INITIAL MOTION ESTIMATE IS FASTER THAN BEFORE...030/17. DANIELLE
IS CURRENTLY ACCELERATING TOWARD THE NORTH-NORTHEAST AS AN UPPER
TROUGH DIVES INTO THE WEST ATLANTIC OCEAN.   IN 24-36 HOURS...THE
THE TROPICAL CYCLONE SHOULD BRIEFLY SLOW DOWN DUE TO A FAST-MOVING
MID-LATITUDE RIDGE TO ITS NORTH.   INCREASING SOUTHWESTERLY FLOW
BETWEEN A LARGE CENTRAL ATLANTIC RIDGE AND ANOTHER MID-LATITUDE
TROUGH SHOULD THEN CAUSE DANIELLE TO BEGIN MOVING RATHER QUICKLY TO
THE NORTHEAST IN A FEW DAYS. WHILE MOST OF THE MODELS ARE IN
REASONABLE AGREEMENT BEFORE THE SYSTEM BECOMES EXTRATROPICAL...THEY
WILDLY DIVERGE FROM THAT POINT ONWARD.  THE NHC FORECAST IS
ADJUSTED EAST OF THE PREVIOUS ONE...CLOSE TO A BLEND OF THE
ECMWF/GFS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0300Z 31.5N  58.8W    90 KT
 12HR VT     29/1200Z 34.2N  56.8W    85 KT
 24HR VT     30/0000Z 37.5N  54.7W    75 KT
 36HR VT     30/1200Z 39.4N  52.5W    70 KT
 48HR VT     31/0000Z 40.8N  48.7W    65 KT
 72HR VT     01/0000Z 45.0N  34.0W    65 KT...POST-TROP/EXTRATROP
 96HR VT     02/0000Z 52.5N  30.0W    55 KT...POST-TROP/EXTRATROP
120HR VT     03/0000Z...ABSORBED

$$
FORECASTER BLAKE



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