Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 151842

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
142 PM EST Fri Dec 15 2017

.SHORT TERM (This Afternoon-Saturday)...
Water vapor imagery and upper air plots showing upper
low continues to spin over Mexico while Great Lakes upper
trough swings well NE of the region keeping WSW flow aloft
over the Gulf and state this afternoon-evening. Western
upper low to slowly move eastward Saturday with ridging
beginning to build from the N Carib over the state.

At the surface the weak slow moving cold front continues to
sag into the FL Big Bend and C Gulf this afternoon. Shearing
upper support to push frontal boundary down the FL Peninsula
tonight with only about a 10% chance of light rain ahead of
and along the front. Some moisture pooling ahead of the
front to produce patchy fog especially over southern half of
the forecast area and fog prone areas overnight. Weak high
pressure centered in the Southern Plains this afternoon to
build into the region behind the front tonight into
Saturday morning bringing slightly drier airmass to the
area. Temps tonight to range from near normal over the
Nature Coast to above normal in SW FL. On Saturday, expect
passing cirrus overhead with comfortable humidity levels
and temps around seasonal averages.

.MID TERM/LONG TERM (Saturday Night - Friday)...
The period begins with surface high pressure off the Mid-
Atlantic coast with easterly flow and dry conditions. A
shortwave moving through the Southern Plains will help to
amplify a ridge across the Southeast and this will promote
well above average temperatures to return to the area for
the first part of the week.

Model agreement begins to diverge somewhat by Wednesday as the
GFS/Canadian suggests a weak cold front will work its way across the
peninsula while the Euro is never able to break the ridge down and
keeps precipitation to the north of Florida. With the operational
ECMWF being on the drier/warmer side of its ensemble spread, and the
GFS suggesting at least some synoptic support from a progressive
shortwave, will keep low-medium PoPs in the forecast for now.
Regardless, this front will not have a significant impact on
temperatures and dewpoints...Another deep ridge builds back
in to close out the work week.


VRF conditions expected all sites this afternoon and evening.
Patchy fog for possible MVFR/IFR vsbys/cigs mainly over
southern terminals aft 06Z through about 13Z. VRF expected
to return to all sites aft 13Z Saturday.


A weak front will slowly sag through the Gulf this afternoon
into tonight with westerly winds and seas ahead of the front.
High pressure will build into the region late tonight through
Saturday with winds and seas veering NE-E. High pressure to
move into W Atlantic with E winds and seas Sun. Evening surges
will briefing increase winds and seas this weekend into Monday.
Another weak front will move into the region early next week.


Patchy fog possible tonight especially over inland and southern
fog prone areas. Drier airmass to filter into the region Saturday
with RHs dropping into the mid 30% range over the N Nature Coast.
Low level moisture and temps to increase Sunday through early
next week.


.Preliminary Point Temps/PoPs...
TPA  56  73  58  78 /  10   0   0   0
FMY  57  77  59  81 /   0   0   0   0
GIF  53  73  55  79 /   0   0   0   0
SRQ  56  73  57  77 /  10   0   0   0
BKV  49  71  51  78 /  10   0   0   0
SPG  56  72  59  77 /  10   0   0   0


Gulf waters...None.


MID TERM/LONG TERM/DECISION SUPPORT...42/Norman is the U.S. government's official web portal to all federal, state and local government web resources and services.