Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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387
FXUS62 KTBW 110815
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
315 AM EST Mon Dec 11 2017

.SHORT TERM (Today through Tuesday)...
Morning IR and water vapor satellite imagery is showing a
cool and dry airmass in place across the area as high
pressure fills in from the Gulf in the wake of the recent
cold front. Under clear skies and light winds, a strong
radiational cooling setup is allowing temperatures to drop
quickly early this morning, with freezing conditions already
being reported over parts of the Nature Coast and an
isolated spots farther south. Additionally, much of the area
will likely experience at least patchy frost this morning
as dewpoint depressions are already near zero. After the
cool start to the morning, the clear skies and light winds
will allow temperatures to begin to moderate from what were
seen yesterday, although afternoon highs will still be a few
degrees below normal, generally topping out in the 60s.
Lows tonight will still be cool, but not cool enough to
approach freezing, with low over the interior generally in
the low to mid 40s, and around 50 near the coast.

On Tuesday, a mid level trough swinging east through the
eastern CONUS will push a dry surface cold front into the
Florida Peninsula. Moisture will not have enough of an
opportunity to return before the front arrives, so rain
chances will remain minimal. Breezy northwest winds along
and behind the front will produce high surf and an increased
risk of rip currents along area beaches as well on Tuesday.
Since the cold front does not arrive until fairly late in
the day, temperatures will continue to moderate, with highs
able to reach into the upper 60s to mid 70s before the cold
air advection kicks in.

.LONG TERM (Tuesday Night - Sunday)...
A highly amplified upper air pattern featuring strong upper
level ridging over the western U.S. and strong upper level
troughing over the eastern U.S. will remain in place
through Thursday. Thereafter the flow pattern is forecast to
de-amplify and become more progressive in nature during
Friday and into next weekend.

At the start of the period a cold front will be exiting to
the south of the forecast area. A brisk northwest to
northerly wind flow in the wake of the front will bring
another reinforcing shot of cool dry air into the region
with cool dry conditions expected during Wednesday and
Wednesday night as surface high pressure builds in from the
west and over the forecast area.

During Thursday and Thursday night the high will shift
southeast into the Atlantic as another short wave trough
and attendant cold front approach from the northwest. The
GFS and Canadian show this front moving south through the
forecast area on Friday, while the Euro remains slower as it
develops a weak area of low pressure along the front over
the northeast Gulf on Friday and depicts a frontal passage
during late Friday night or early Saturday morning.

Despite these differences model trends do show a little
better moisture recovery ahead of the front, so will use a
consensus of model output for now and depict pops in the 30
to 40 percent range during Friday and Friday night, with
some lingering showers (Pops 20 percent) continuing across
central and southern zones through early Saturday morning
(to account for the slower Euro solution) with the passage
of the front followed by another surge of cooler and drier
weather for Saturday afternoon and night as surface high
pressure builds in over the area in the wake of the front.
Zonal flow aloft and surface high pressure over the region
should maintain dry weather on Sunday along with slowly
moderating temperatures.

Below normal temperatures at the start of the period with
lows in the mid and upper 30s north, lower to mid 40s
central interior, and upper 40s south and along the coast,
with highs in the upper 50s north to lower to mid 60s
central and south on Wednesday will gradually moderate back
toward seasonal norms toward the end of the week, before
another brief cool down occurs during Saturday and Saturday
night in the wake of the front. Temperatures will then
modify again on Sunday with overnight lows rebounding into
the 50s with daytime highs on Sunday climbing into the lower
to mid 70s.

&&

.AVIATION...
VFR conditions will hold through the next 24 hours under light
northeast winds, turning to northwest in the afternoon.

&&

.MARINE...
High pressure building into the Gulf will keep winds and
seas light today and into Tuesday. A dry cold front will
move south through the coastal waters Tuesday, with winds
briefly increasing to advisory levels before subsiding
Tuesday night. High pressure will then take hold again until
Friday, when another cold front moves through, causing
breezy winds and chances for showers.

&&

.FIRE WEATHER...A much drier airmass remains in place
across the area today, with relative humidity percentages
forecast to drop into the low 30s and upper 20s for a few
hours this afternoon. However, light winds and low ERC
values will not line up to create Red Flag conditions.
Moisture will briefly increase on Tuesday, before another
cold front moves in and supplies another shot of cooler and
drier air. Critical relative humidity values will be
possible again Wednesday afternoon, but light winds and low
ERC values will once again prevent Red Flag conditions.

&&

.Preliminary Point Temps/PoPs...
TPA  64  51  72  46 /   0   0  10   0
FMY  67  48  75  49 /   0   0  10   0
GIF  63  45  72  41 /   0   0  10   0
SRQ  65  50  73  50 /   0   0  10   0
BKV  63  43  72  39 /   0   0  10   0
SPG  63  55  72  50 /   0   0  10   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Freeze Warning until 8 AM EST this morning for Coastal
     Citrus-Coastal Hernando-Coastal Levy-Inland Citrus-
     Inland Hernando-Inland Levy-Inland Pasco-Sumter.

Gulf waters...None.
&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...18/Fleming
MID TERM/LONG TERM/DECISION SUPPORT...57/McMichael



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