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TROPICAL STORM FIONA DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062016
1100 AM AST SUN AUG 21 2016

Strong westerly shear continues to take a toll on Fiona.  After
becoming devoid of convection overnight, new convective cells have
developed around the small circulation, but there is not much
organization to the thunderstorm activity.  Besides, the clouds tops
are already being sheared eastward by strong upper-level westerly
flow.  Satellite intensity estimates are gradually decreasing, so
the initial wind speed has been lowered to 35 kt.  Fiona will be
moving through a hostile environment consisting of strong westerly
shear and dry mid-level air during the next day or two.  This
should result in some additional weakening, and Fiona is forecast
to become a tropical depression during the next 24 hours, and a
remnant low in a couple of days.  If the small circulation can
survive the next 72 hours or so, environmental conditions could be
conducive for regeneration late in the forecast period.  The GFS and
UKMET models maintain a weak low over the western Atlantic through
day 5, while the ECMWF depicts an open trough of low pressure by 72
hours.  The NHC forecast maintains continuity with the previous
forecast, and shows dissipation around day 5.

Fiona is moving west-northwestward or 295/14 kt.  A low- to
mid-level ridge over the central Atlantic should continue steering
the cyclone west-northwestward during the next couple of days.
Fiona will be nearing a break in the ridge over the western Atlantic
by mid-week which should cause a northwestward turn and reduction in
forward speed.  The new NHC track forecast has been adjusted
slightly southward and is located between the latest multi-model
consensus and the previous NHC track prediction.

FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 22.9N  53.3W   35 KT  40 MPH
 12H  22/0000Z 23.6N  55.5W   35 KT  40 MPH
 24H  22/1200Z 24.3N  58.1W   30 KT  35 MPH
 36H  23/0000Z 25.0N  60.3W   30 KT  35 MPH
 48H  23/1200Z 25.8N  62.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  24/1200Z 27.7N  65.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  25/1200Z 30.5N  67.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  26/1200Z...DISSIPATED

$$
Forecaster Brown

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