[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT44 KNHC 190833
TCDAT4
TROPICAL STORM DANIELLE DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU AUG 19 2004

DANIELLE REMAINS STRONGLY SHEARED...BUT THE CYCLONE HAS CONTINUED TO
DEVELOP DEEP CONVECTION IN THE NORTHEAST QUADRANT. THE INITIAL
INTENSITY IS A BLEND OF DVORAK T-NUMBERS OF T2.5...OR 35 KT AND A
DVORAK CURRENT INTENSITY ESTIMATE OF T3.0...OR 45 KT...FROM ALL
THREE SATELLITE AGENCIES. THIS IS ALSO CONSISTENT WITH AN EARLIER
QUIKSCAT OVERPASS SHOWING 40 KT UNCONTAMINATED WINDS.

THE INITIAL MOTION ESTIMATE IS 040/04. DANIELLE HAS MADE SOME LARGE
WOBBLES IN THE TRACK OVER THE PAST 12 HOURS...BUT THE GENERAL
MOTION HAS BEEN TOWARD THE NORTHEAST...ALBEIT AT A MUCH SLOWER
FORWARD SPEED. DANIELLE IS EXPECTED TO REMAIN UNDER THE INFLUENCE
OF MID- TO UPPER-LEVEL SOUTHWESTERLY OR EVEN WESTERLY SHEAR
THROUGHOUT THE FORECAST PERIOD SINCE THE CYCLONE WILL BE PUSHING
INTO A STRONG LOW-LEVEL RIDGE/SURFACE HIGH PRESSURE AREA LOCATED TO
THE NORTHEAST. THE FORECAST TRACK HINGES UPON THE ASSUMPTION THAT
DANIELLE WILL CONTINUE TO GENERATE INTERMITTENT DEEP CONVECTION TO
MAINTAIN THE VERTICAL CIRCULATION. HOWEVER...IF THE CONVECTION
WEAKENS SIGNIFICANTLY OR DISSIPATES...THEN DANIELLE WILL RAPIDLY
SPIN DOWN AND POSSIBLY BECOME STATIONARY OR EVEN MOVE BACK TO THE
WEST OR SOUTHWEST LIKE THE NOGAPS...GFS...AND GFDN MODELS ARE
INDICATING. HOWEVER...IF THE LATTER SCENARIO SHOULD HAPPEN...THEN
DANIELLE WOULD NOT REMAIN A TROPICAL CYCLONE FOR MORE THAN 24 HOURS
...IF THAT. THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK.

DANIELLE IS EXPECTED TO REMAIN OVER 25-26C SEA SURFACE TEMPERATURES
THROUGH 48 HOURS OR SO...WHICH WOULD GENERALLY ALLOW FOR AT LEAST
INTERMITTENT DEEP CONVECTION TO DEVELOP AND KEEP DANIELLE ALIVE. BY
72 HOURS...ASSUMING DANIELLE IS STILL A TROPICAL CYCLONE...
INTERACTION WITH A FRONTAL SYSTEM AND A STRONG MID-LEVEL SHORTWAVE
TROUGH APPROACHING FROM THE WEST AND NORTHWEST IS EXPECTED TO BRING
ABOUT EXTRATROPICAL TRANSITION...OR POSSIBLY EVEN ABSORPTION INTO A
LARGER EXTRATROPICAL CYCLONE. THE SHIPS MODEL WAS FOLLOWED CLOSELY.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      19/0900Z 30.0N  37.5W    40 KT
 12HR VT     19/1800Z 30.4N  37.0W    35 KT
 24HR VT     20/0600Z 31.1N  36.2W    30 KT
 36HR VT     20/1800Z 32.0N  35.0W    25 KT
 48HR VT     21/0600Z 32.9N  33.6W    25 KT...BECOMING EXTRATROPICAL
 72HR VT     22/0600Z 34.5N  30.5W    25 KT...EXTRATROPICAL
 96HR VT     23/0600Z 36.5N  28.0W    25 KT...EXTRATROPICAL
120HR VT     24/0600Z...ABSORBED BY EXTRATROPICAL LOW


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