Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 271814

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
214 PM EDT Thu Jul 27 2017

.SHORT TERM (Tonight - Friday)...
In the mid/upper levels, ridging continues to slowly get pushed
southward while troughing extends from Georgia across the Florida
panhandle and into the northeast Gulf of Mexico. The trough deepens
through Friday and the ridge will be pushed further south into the
Florida Strait by Friday afternoon. On the surface, a weak area of
low pressure sits over southeast Georgia in between two separate
areas of high pressure located north of the Bahamas and the
northern Gulf of Mexico. The combination of the onshore wind flow
between the low over southeast Georgia and the high in the Gulf of
Mexico will keep abundant moisture over the area and will also help
to keep the highest rainfall chances over the inland areas later in
the evening hours. The main weather concern once again today has
been hot temperatures. Most places saw heat indices near 100 degrees
with some inland areas reaching 110 degrees. Things will cool down
this evening, but will still be warm and muggy overnight with low
temps in the mid to upper 70`s with humidity values near 100 percent
in some places.

On Friday, conditions will only be slightly different than what we
saw today. The surface ridge slips further southward which will
produce a more southwest onshore flow, which in turn will bring an
increase in moisture, with expected PWAT values to increase to 1.8 -
2.0 inches across the region. Chances of rain will be slightly
higher (30-50 POPs) over the inland counties. Temperatures will be
slightly cooler, but still above average with the heat indices. Heat
indices will approach the upper 90s in some locations by late
morning with most of the region seeing 100 degree heat indices
through the afternoon on Friday.


.Long Term (Friday Night-Thursday)...
A vigorous upper trough will be moving through the southeast U.S.
towards north Florida on Saturday with the surface sub-tropical high
suppressed over south Florida. The short wave will have a
corresponding surface front with moisture and convection pushing
toward north Florida. By Sunday the front will be across north
central Florida with areas of rain and thunderstorms in the vicinity
that become scattered over the southern forecast area. The models
are in agreement with the front becoming stationary across central
Florida as the surface and primary upper low move slowly northeast
along the eastern seaboard. Weak areas of low pressure will be
moving from west to east along the frontal zone and will create
periods of enhanced convection while in-between the areas of
precipitation will subside. With cloudy skies, the daytime
temperatures will be in the mid 80s to near 90 with lows in the mid
to upper 70s.


VFR conditions are expected to prevail through the period.
TPA/PIE/SRQ should remain rain free today, but will hold VCTS for
LAL/PGD/FMY/RSW between 18Z to 00Z. Winds have turned on shore out
of the west-southwest with the sea breeze remaining less than 10
knots through the evening, then becoming light and variable
overnight. No other aviation impacts expected.


High pressure in the Gulf of Mexico will keep mostly rain free
conditions, light winds below 10 knots and minimal seas less than 2
feet through the remainder of the week and into the beginning of the
weekend. A frontal boundary approaches the area early Sunday and
will bring increasing rain and storm chances over the coastal
waters. The tighter pressure gradient between this front and high
pressure to the south will also increase the southwest winds to 10-
15 knots, which will also build the seas to 3-4 feet in some areas.
Wind and seas will be higher in the vicinity of thunderstorms,
otherwise no marine headlines are anticipated through the period.


No fire weather concerns are expected for the remainder of the week
and into the weekend as humidity levels remain above critical
levels and ERC values remain low.


.Preliminary Point Temps/PoPs...
TPA  79  91  80  89 /  10  10  20  30
FMY  77  93  78  91 /  20  20  20  30
GIF  76  93  77  91 /  20  20  10  30
SRQ  78  90  80  89 /  20  20  20  30
BKV  74  91  75  90 /  10  10  20  30
SPG  80  90  80  88 /  10  10  20  30


Gulf waters...None.


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