Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 211124

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
724 AM EDT Thu Sep 21 2017

21/12Z TAFs. VFR conditions will prevail at all terminals through
the next 24 hours. Very few clouds this morning, then slightly
increasing to a SCT CU deck this afternoon. Northern terminals will
stay dry while PGD/FMY/RSW may see a stray shower this afternoon, so
will cover that with VCSH after 18Z. Winds will remain light less
than 10 knots. No other aviation impacts expected.


.Prev Discussion... /issued 431 AM EDT Thu Sep 21 2017/

SHORT TERM...(Today-Friday)...
High pressure will continue to ridge southward from the northeast
U.S. keeping an east to northeast flow across the region. Moisture
will increase slightly today leading to a few showers and possibly
a thunderstorm during the afternoon and evening, but coverage
will remain 20 to 30 percent with best chances along the northern
Nature Coast and near the southwest Florida coast late in the day
and this evening. Otherwise, skies will be partly to mostly sunny
with temperatures climbing into the lower 90s. The west coast sea
breeze will try to develop near the coast during this afternoon,
but will not make much headway moving inland like the last couple
of days. For tonight the east coast sea breeze will move westward
bringing an increase in the flow during the evening and helping to
push any convection out into the eastern gulf. Skies will then be
mostly clear to partly cloudy overnight with temperatures falling
to around 70 across much of the Nature Coast with lower to middle
70s elsewhere. On Friday some more moisture will move in from the
east during the day and this combined with daytime heating will
help pop scattered showers and thunderstorms across the entire
region during the afternoon and evening. Temperatures will
continue to be near to a couple of degrees above normal with
daytime highs in the upper 80s to lower 90s.

MID TERM/LONG TERM...(Friday Night through Thursday)...
At the start of the medium range period, a high amplitude upper
trough will stretch across the Intermountain West with potent
upper ridging extended from the Great Lakes region into the
northwestern Gulf of Mexico. Jose and Maria will continue to spin
across the far western Atlantic Ocean. Meanwhile, the surface
ridge axis will extend north of the region with modest easterly
flow to start the period.

Heading into the weekend, as Maria lingers off the east Florida
coast, gradient flow will tighten with breezy easterly winds
becoming established. With deep moisture in place, Saturday looks
to hold the highest chance of more widespread rainfall. Showers
and storms look to develop over eastern and central portions of
the peninsula first, then shift westward during the afternoon and
evening hours within the easterly flow. Sunday will feature
similar conditions with scattered afternoon showers and storms,
but as Maria gains latitude, a more northeasterly wind flow will
overspread the region. This will usher in slightly drier air,
limiting rain chances north of I-4.

As we head into the start of next week, another dry period look to
unfold. With Maria continuing to lift northward, winds will
continue to shift to the north, allowing drier air to advect into
the region. This will progressively lead to lesser and lesser
chances of rain each day, with dry conditions expected by mid week
as northerly flow persists.

As far as temperatures go, expect very summery warmth to persist
with highs in the 90s and lows in the 70s. With the drier air
expected mid to late next week, we could see highs a tad hotter
and lows a touch cooler as drier air tends to see greater diurnal
temperature fluctuations than our typically moist air.

VFR conditions should generally prevail through tonight. Some
patchy MVFR ceilings could develop with daytime heating during mid
to late morning today, then isolated to scattered showers and a
few thunderstorms could cause some MVFR/local IFR conditions
during the afternoon and evening.

The east to northeast flow will continue and shift to more
northerly along the coast during this afternoon and again Friday
afternoon as the west coast sea breeze tries to develop. Will see
an evening surge tonight and again Friday evening, but winds
should remain around 15 knots or less. For Saturday the east to
northeast flow will persist at about 10 to 15 knots preventing the
west coast sea breeze from developing. Then during Sunday into
Monday the flow will diminish some as Maria moves by well to the
east of Florida with the west coast sea breeze trying to develop
each afternoon.

No fire weather concerns for the next few days.


.Preliminary Point Temps/PoPs...
TPA  91  76  90  75 /  10  10  50  20
FMY  92  74  91  75 /  30  20  50  30
GIF  92  73  90  74 /  10   0  50  20
SRQ  91  74  90  75 /  10  10  50  30
BKV  92  70  90  72 /  20  10  50  10
SPG  91  76  89  76 /  10  10  50  20


Gulf waters...None.


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