Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 200816
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
316 AM EST Mon Nov 20 2017

...INCREASING RAIN CHANCES TUESDAY THROUGH THANKSGIVING DAY...

.SHORT TERM (Today - Tuesday)...
A cold front across the southern peninsula early this
morning will stall out across the Florida Straits by later
this afternoon and early tonight as surface high pressure
over the southeastern states drifts east-northeast toward
the mid Atlantic coast. Cooler and drier air will continue
to advect into the region the remainder of the morning on a
breezy northerly wind flow with temperatures bottoming out
in the mid to upper 40s across the Nature Coast, lower to
mid 50s central interior, and mid to upper 50s across
southwest Florida toward sunrise. Dry stable conditions
associated with the high to the north will initially support
sunny skies through the late morning, but as the flow
quickly veers into the east-northeast as the high moves east
expect to see a slow increase in clouds from east to west
during the afternoon as low level moisture increases across
the region. After a cool start temperatures will rebound
quickly back into the lower to mid 70s north, and mid to
upper 70s central and south during the afternoon.

Tonight the surface high along the mid Atlantic coast will
slide east into the Atlantic as a series of vort maxes within
the amplifying upper level trough over the Gulf approach and
slide east across the region during the day on Tuesday. As
the high moves further to the east a developing southeast to
southerly wind flow will help to draw the stalled frontal
boundary to the south back to the north as a warm front on
Tuesday. Increasing low level moisture combined with lift
along the warm front and a possible weak surface low
reflection developing along the front over the northeast
Gulf, and additional dynamic support aloft will support
scattered to numerous showers and isolated thunderstorms
(Pops 60 to 70 percent) developing across the region during
the day with some locally heavy rain possible in some
locations as all of these features affect the region.

Temperatures tonight into Tuesday will modify back to near
seasonal levels as cloud cover and rain chances increase
with lows tonight in the mid to upper 50s north, and lower
to mid 60s central and south, with highs on Tuesday reaching
the lower to mid 70s north into central zones, and mid to
upper 70s south.

.LONG TERM (Tuesday Night through Sunday)...
The dominant weather feature this week will be a persistent
mid level shortwave trough that will dig into the Gulf of
Mexico Tuesday night and Wednesday and gradually shift east
through the Florida Peninsula through next weekend. At the
surface, this shortwave will fuel a pattern of unsettled
weather, as a series of surface lows lift northeast through
the forecast area on the tail end of a warm front Tuesday
night through late in the week. This will result in a rather
wet pattern through Friday, with daily chances for showers
and a few thunderstorms. In general, the GFS is showing a
stronger mid level shortwave, resulting in higher rain
chances than the ECMWF throughout the week, though otherwise
the long range models are in good agreement with the
overall pattern of daily rain chances.

By Friday afternoon and into the weekend, surface ridging
will be building into the central Gulf and across northern
Florida, allowing a drier and slightly cooler air mass to
filter into the forecast area. This will translate to a
rather pleasant weekend, with generally rain free conditions
Saturday and Sunday under mostly sunny skies. High
temperatures are expected to run in the low to mid 70s,
with cool mornings, and low humidity.

&&

.AVIATION...
Lingering IFR cigs impacting KFMY and KRSW should move to
the south by 08Z with VFR returning. VFR with clear skies
is expected at all terminal sites through 20Z as drier air
filters into the region in the wake of a cold front. After
20Z sct040-050 is expected with bkn040-050 cigs developing
at KPGD, KFMY, and KRSW after 21Z with these cigs then
spreading north to the remainder of the terminals after 01Z
tonight as moisture rapidly increases across the region.
North winds in the 10 to 12 knot range with a few higher
gusts this morning will become northeast to east at 8 to 10
knots after 18Z which will continue through the end of the
forecast period.

&&

.MARINE...
Strong and gusty north winds and elevated seas in the wake
of the cold front will support hazardous boating conditions
over the Gulf waters through early this morning with small
craft advisory headlines remaining in effect for all of the
Gulf waters including the Tampa Bay waters until 7 AM EST
this morning. Winds and seas should diminish and subside
some but likely remain in the cautionary range through the
remainder of the day especially over the offshore waters as
the flow quickly veers into the northeast and east as high
pressure to the north slides east-northeast toward the mid
Atlantic coast. Tonight through the remainder of the week an
area of low pressure is expected to develop over the
eastern Gulf of Mexico, with this low tracking east
northeast across the peninsula during Wednesday through
Friday. Although winds and seas are not expected to
significantly increase with this low rain chances will with
scattered to numerous showers and isolated storms expected
Tuesday through Friday as this storm system affects the
region.

&&

.FIRE WEATHER...
Drier air will continue to advect into the region early this
morning in the wake of a cold front, but as the flow
quickly veers into the northeast and east by late morning
and into the afternoon an increase in Atlantic moisture is
expected which will continue tonight through the remainder
of the week along with increasing rain chances as a
developing storm system over the Gulf affects the region.
Given the short lived nature of the dry air humidity values
should remain above critical levels today and through the
remainder of the week with no fire weather issues expected
at this time.

&&

.Preliminary Point Temps/PoPs...
TPA  76  63  75  64 /   0  10  70  20
FMY  79  66  80  65 /   0  20  70  20
GIF  75  62  76  63 /   0  10  70  30
SRQ  77  65  76  64 /   0  10  70  20
BKV  75  59  75  60 /   0  10  70  30
SPG  75  65  74  64 /   0  10  70  20

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...Small Craft Advisory until 7 AM EST this morning for
     Coastal waters from Bonita Beach to Englewood FL out
     20 NM-Coastal waters from Englewood to Tarpon Springs
     FL out 20 NM-Coastal waters from Tarpon Springs to
     Suwannee River FL out 20 NM-Tampa Bay waters-Waters
     from Bonita Beach to Englewood FL out 20 to 60 NM-
     Waters from Englewood to Tarpon Springs FL out 20 to
     60 NM-Waters from Tarpon Springs to Suwannee River FL
     out 20 to 60 NM.

&&

$$

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



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