[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT45 KNHC 151441
TCDAT5
TROPICAL STORM EARL DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN AUG 15 2004

EARL APPEARS WELL-ORGANIZED ON SATELLITE IMAGES...BUT THE HURRICANE
HUNTERS REPORT THAT THE LOW-LEVEL CIRCULATION IS NOT VERY
WELL-DEFINED...AND IN FACT RECENT OBSERVATIONS FROM THE PLANE
SUGGEST THAT THE CIRCULATION MAY NOT BE QUITE CLOSED OFF.  THIS IS
PROBABLY DUE TO THE VERY FAST FORWARD MOTION.  THE UPPER-LEVEL
OUTFLOW HAS BECOME RATHER IMPRESSIVE...EXCEPT TO THE EAST.  WATER
VAPOR ANIMATION SUGGESTS THAT VERTICAL SHEAR WILL REMAIN LOW AHEAD
OF THE STORM...SO STRENGTHENING IS LIKELY.  THE OFFICIAL FORECAST
IS RATHER SIMILAR TO THE SHIPS GUIDANCE.  LATE IN THE PERIOD...MORE
SIGNIFICANT STRENGTHENING IS CERTAINLY POSSIBLE BECAUSE OF THE VERY
FAVORABLE OCEANIC ENVIRONMENT.  HOWEVER THERE IS LITTLE...IF
ANY...SKILL IN PREDICTING SUCH EVENTS.

BASED ON THE EARLIER AIRCRAFT FIX...INITIAL MOTION IS 280/24.  THE
STEERING ENVIRONMENT WILL BE DOMINATED BY A STRONG MID-LEVEL RIDGE
TO THE NORTH OVER THE NEXT FEW DAYS.  BEYOND 72 HOURS...THE TRACK
FORECAST BECOMES MORE PROBLEMATIC.  MOST OF THE GUIDANCE INDICATES
THAT ENOUGH OF A RIDGE WILL BE MAINTAINED TO THE NORTH TO PREVENT A
SIGNIFICANT RIGHT TURN.  HOWEVER...THE U.K. MET. OFFICE MODEL IS AN
OUTLIER AND DOES SHOW EARL TURNING NORTHWARD OVER THE GULF BY DAY
5.  THE CURRENT NHC TRACK FORECAST IS A OF THE GUIDANCE SAVE THE
AFOREMENTIONED U.K. MET. MODEL.  IT SHOULD BE BORNE IN MIND THAT
THE TRACK ERROR AT 120 HOURS IS TYPICALLY A FEW HUNDRED MILES...SO
ONE SHOULD NOT FOCUS ON THAT EXACT POINT.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      15/1500Z 11.9N  62.0W    40 KT
 12HR VT     16/0000Z 12.9N  65.3W    45 KT
 24HR VT     16/1200Z 14.0N  69.5W    50 KT
 36HR VT     17/0000Z 15.3N  73.4W    55 KT
 48HR VT     17/1200Z 16.5N  76.9W    60 KT
 72HR VT     18/1200Z 18.5N  82.5W    70 KT
 96HR VT     19/1200Z 21.0N  86.5W    80 KT
120HR VT     20/1200Z 24.0N  89.0W    90 KT

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