Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 261843
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
243 PM EDT Tue Sep 26 2017

.SHORT TERM (Tonight - Wednesday)...
An amplified upper air pattern featuring a deep upper level
trough out west and strong upper level ridging over the
eastern U.S. will remain in place through the short term
period. Closer to home an upper level trough extending
southwestward from Maria offshore the mid Atlantic coast to
the northeastern Gulf will remain in place through Wednesday
as hurricane Maria is forecast to move north through
tonight, then north-northeast away from the U.S. east coast
on Wednesday. Tonight any lingering showers or storms over
inland areas and across southwest Florida should wind down
by sunset with loss of daytime heating and weakening
boundary interactions with mostly clear to partly cloudy
skies expected overnight.

On Wednesday weak high pressure will remain in control. Low
rain chances are again expected to continue as a light
north to northwest wind flow and drier air remains over much
of the region. The exception to this will again be over
inland locations where isolated to widely scattered showers
or storms will be possible along the inland moving sea
breeze boundaries during the afternoon and across southwest
Florida where better moisture will continue to reside.

Temperatures will remain slightly above normal through the
period with overnight lows in the upper 60s to around 70
across the Nature Coast, and lower to mid 70s central and
south with daytime highs on Wednesday climbing to around 90
along the coast, and lower to mid 90s inland.

.MID/LONG TERM (Wednesday Night through Next Tuesday)...
A low aloft continues over the area through the weekend then
slips south as ridging builds in for the early part of
next week. Surface troughing across FL and the Gulf pulls
away to the northeast by the end of the week. During the
weekend Canadian high pressure slides in across the Great
Lakes then moves to New England. The high builds down into
the Gulf...pushing a front ahead of it...and sets up
easterly flow across FL with an embedded low/inverted trough
traversing the southern part of the state. The latest GFS
and ECMWF handle this feature similarly but the GFS is a bit
faster and more defined.

The drier air of the past couple of days continues into Thu-
Fri with model PWAT values in the 1.3 to 1.6 inch range.
Then strengthening easterly flow will provide increasing
moisture...with PWAT climbing into the 1.9 to over 2 inch
range for later in the weekend then tapering off...from
north to south...a bit for early next week. Limited rain
chances will be confined to the south Thu...increase and
spread into the central counties Fri...then encompass the
entire area during the weekend. Showers will be scattered to
numerous with isolated to scattered thunderstorms. The
higher coverage will be toward southern locations where the
deepest moisture will be. Temperatures will be on the warm
side for the lows. The highs start off warm but then dip to
around normal for the weekend and beyond thanks to increased
rainfall and cloud cover.

&&

.AVIATION...
Some isolated to widely scattered shra/tsra may impact KPGD,
KFMY, KLAL, and KRSW terminals between 20-24Z and have
included VCTS at these sites, otherwise VFR will prevail.
Some brief IFR vsbys from patchy fog may also impact KPGD
and KLAL between 09-13Z Wednesday morning, otherwise VFR
will continue. West winds in the 7 to 10 knot range this
afternoon will become light and variable after 02Z tonight,
then becoming west at 6 to 8 knots Wednesday afternoon as
the sea breeze redevelops and moves inland.

&&

.MARINE...
Tranquil boating conditions will continue over the Gulf
waters tonight through the remainder of the week as high
pressure remains in control, with a weak pressure pattern
supporting an onshore sea breeze component developing along
the coast each afternoon. During the upcoming weekend and
into early next week strong high pressure building in north
of the waters and lower pressure over the western Caribbean
and southeastern Gulf will support a tightening pressure
gradient across the region which will result in an
increasing easterly wind flow and building seas over the
Gulf waters with cautionary or low end small craft
conditions a good bet by late in the weekend and continuing
into early next week. A slow increase in moisture will also
support increasing chances for showers and storms over the
waters as well.

&&

.FIRE WEATHER...
Humidity values in the 40 to 50 percent range can be
expected across the region the remainder of today and
through Thursday as slightly drier air remains in place. A
slow increase in moisture and rain chances are expected
Friday and into the upcoming weekend. With humidity values
remaining above critical levels no fire weather issues are
expected through the period.

&&

.HYDROLOGY...
While moderate to major flooding continues on the
Withlacoochee River in Pasco and Hernando Counties, the
river is slowly receding. As the water routes farther
downstream, minor flooding is still forecasted to begin over
the next couple of days in Northern Citrus County. The
Withlacoochee River has not flooded in some of these
locations within the last 10+ years. Elsewhere, levels
continue to recede along most of West Central Florida`s
rivers. With no widespread rainfall expected over the next
several days, additional flooding is not expected to occur.
Most of the flooding that occurred from Hurricane Irma
resulted in the worst flooding many places have seen in the
last 50-70 years. For example, the official crest on the
Peace River At Arcadia of 19.20 feet was the 3rd highest on
record and the worst flooding since 1933.

&&

.Preliminary Point Temps/PoPs...
TPA  76  92  77  91 /  10  10   0  10
FMY  76  91  75  90 /  10  20  10  30
GIF  73  94  73  92 /  10  20  10  10
SRQ  76  91  75  87 /  10  10   0  20
BKV  72  93  72  92 /   0  10   0  10
SPG  77  90  77  91 /  10  10   0  10

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...57/McMichael
MID TERM/LONG TERM/DECISION SUPPORT...09/Rude
HYDROLOGY...42/Norman



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