Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 200821
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
321 AM EST Mon Feb 20 2017

.SYNOPSIS...
Aloft - A long wave trough extended from the Canadian Rockies
to north-central Mexico while a ridge reached from the Gulf
of Mexico to over and west of Hudson Bay. Surface - A low
pressure center was on the ND/SD line...with a warm front
across the upper Mid-West...and a cold front south to the
central high plains. High pressure over James Bay stretched
down to western Cuba.

&&

.SHORT TERM (Today - Tuesday)...
The trough and ridge slide east...with the southern end of
the trough deepening into a low over the northwest Gulf
while the ridge reaches from the Bahamas to the Canadian
Maritimes. The surface ridge slips to the eastern seaboard
while a weak trough begins to form underneath the upper low.

The deep layer ridging moving across the area will dominate
with a stable...warm...and generally dry air mass. Model
PWAT range about 0.75 inches today then creep up to almost
1 inch during Tue. The forecast is for temperatures above
normal under mostly sunny/clear skies. Except...ongoing fog
is expected to continue and thicken through sunrise then
begin to lift by 9-10 AM. Currently a dense fog advisory is
in effect for Polk county primarily due to the smoldering
wildfire in the southeast corner of the county whose smoke
could enhance any fog and drive visibilities down to near
zero. Elsewhere expect areas of fog...locally dense at
times especially from the Tampa Bay region north. The
visibilities have been fluctuating...will hold off on a
dense fog advisory and handle with special weather
statements.

.LONG TERM (Tuesday night-Sunday)...
Uncertainty in the mid range as a cut-off low is expected
to be over the Gulf of Mexico Tuesday night...which will
push slowly southeast toward the Florida straits Wednesday
and Thursday. Low confidence concerning areal coverage of
showers and isolated thunderstorms associated with the upper
low as it approaches the Florida peninsula. Currently
trending toward low end pops until evolution of this system
becomes more apparent...as bulk of shower and thunderstorm
activity may sink south of the forecast area. But potential
exists for more substantial rainfall/higher pops over west
central Florida.

Weakening area of low pressure will track east of Florida late in
the week with skies gradually clearing across the forecast
area...although no significant airmass change will occur as
temperatures will continue to run several degrees above normal
through the mid/long term period.

A cold front will approach west central Florida over the weekend,
however the front will likely weaken and stall over north Florida as
it becomes parallel to quasi-zonal U/L flow across the Gulf of
Mexico and Florida.  The front will also have little in the way of
deep layer moisture to work with and no U/L support so no shower
activity expected attm.

&&

.AVIATION...
20/06Z-21/06Z. BR/FG already occurring is anticipated
to spread to all terminals with MVFR...mainly for VSBY
through 14Z. TPA/PIE/SRQ could see some IFR while LAL/PGD go
down to IFR/LIFR. Light/calm winds become easterly during
the day but shift to onshore near coast from SRQ north in
the afternoon.

&&

.MARINE...
Sea fog continues but has lessened some and will allow the
advisory to expire at 4 AM. High pressure extending into
the Gulf from Canada will move east across the state then
out over Atlantic to along Latitude 30 North during the
first half of the week...during the latter half a low
pressure system approaches from the west then pass south of
the waters. Winds will gradually veer around at speeds of 15
knots or less. The low will bring some showers and
thunderstorms with it.

&&

.FIRE WEATHER...
Deep layer ridging will provide warm and slightly drier air
for the next couple of day...although there will be enough
moisture to preclude any low RH concerns. Patchy to dense
fog early this morning will lift by 9-10 AM. Winds becoming
easterly tonight along with some slight warming is expected
to limit fog formation tonight into Tue morning. A low
pressure system approaches florida midweek then slips south
of the state...possibly providing some showers and
thunderstorms.

&&

.Preliminary Point Temps/PoPs...
TPA  81  63  80  64 /   0   0   0   0
FMY  85  62  82  63 /   0  10   0   0
GIF  83  60  82  62 /   0   0   0   0
SRQ  80  61  79  62 /   0  10   0   0
BKV  83  56  82  58 /   0   0   0   0
SPG  79  65  78  65 /   0   0   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Dense Fog Advisory until 9 AM EST this morning for Polk.

Gulf waters...Dense Fog Advisory until 4 AM EST early this morning for
     Coastal waters from Englewood to Tarpon Springs FL
     out 20 NM-Tampa Bay waters.

&&

$$

SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WEATHER...09/Rude
MID TERM/LONG TERM/DECISION SUPPORT...13/Oglesby


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