Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 251841

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
241 PM EDT Wed Apr 25 2018

.SHORT TERM (Remainder of today through Thursday)...
Broad cyclonic flow aloft dominates roughly the eastern one-half of
the U.S. as a couple of short wave troughs rotate through. The first
exits the Mid-Atlantic coast this evening while the second...over
the central plains this afternoon...drops into the mid to lower
Mississippi Valley tonight then treks over the Deep South Thu. At
the surface: A low associated with the second short wave trough
follows it eastward...trailing a cold front from the TX coast to the
central Gulf coast and the waters south. High pressure in the
western Gulf and extending to FL this afternoon weakens some as it
shifts to the east and southeast.

A dry air mass...model PWAT values run less than 1 northwesterly
surface and 1000-700mb flow gradually shifts and diminish over night
to southwesterly Thu. The limited dry air stays below 850mb with only
a few to widely scattered clouds expected...mostly clear to clear skies
for the most part. There will be enough moisture along with the lighter
winds over night for some patchy late night fog to form inland.
Low temperatures tonight will be just below normal for northern
locations but normal for central and southern areas. Highs Thu on
the cool side except near normal in the south. Some noticeable
changes are expected to wind up this week...details in the long
term section.

.LONG TERM (Thursday Night -Wednesday)...
At the start of the period a closed low over the southeastern states
will be lifting out to the northeast as an attendant cold front
moves east-southeast into the northern peninsula. A few showers
could be possible across the northern Nature Coast overnight as
the front approaches, otherwise mainly dry weather will continue.

On Friday a short wave trough will dig southeast across the northern
Gulf coast, with this feature then moving across the north-
central Florida peninsula during Friday night. This feature will
help to pull the aforementioned cold front south through the
region during Friday and Friday night. Sufficient moisture return
along and ahead of this front combined with daytime heating,
cooling temperatures aloft, and added upper level forcing from the
short wave should support scattered showers and isolated storms
(Pops 20 to 30 percent) across the forecast area, with best
chances along and to the south of the I-4 corridor. With rather
cold temps aloft (-10 to -12C at 500MB) and an increase in mid and
upper level winds accompanying the short wave a few strong to
possibly severe storms will be possible across central and
southern zones with some hail and strong downburst winds the main

Rain chances will end during Friday night as the short wave exits
to the east and the front moves to the south with drier air
moving into the region in its wake on a northwest to northerly
wind flow with pleasant dry weather expected through the upcoming
weekend as a zonal flow aloft develops and high pressure builds in
over the region.

Now during Monday through Thursday the upper level flow across the
Conus will amplify in response to a strong upper level trough
developing over the western U.S.. As the western U.S. trough
develops downstream upper level ridging will build in over the
eastern U.S. with an attendant surface high building in along the
eastern seaboard. This pattern will support dry conditions and
seasonably warm temperatures with an easterly wind flow across the
forecast area each day through the period.

Near seasonal temperatures at the start of the period will climb
to above normal during the latter part of the weekend and into
next week as heights rise and large scale subsidence from the
building upper ridge increases across the area. Overnight lows
will mainly be in the 60s, with daytime highs in the lower to mid
80s during the weekend climbing into the mid and upper 80s during
early next week.


25/18Z TAFs. VFR. Dry air with westerly flow continues. FEW to SCT
CU/SC through the afternoon...FEW late night ST possible with
limited BR at LAL and PGD. WNW and at times gusty winds back and
diminish overnight with SW winds picking up Thu morning.


Western Gulf high pressure building toward the waters today will
keep gentle to moderate northwest or west winds with seas 3 feet
or less through tonight. Winds become southwest and stay benign
Thu and most of Thu night but begin to increase and shift to the
west and northwest as a cold front approaches...crossing the east
gulf waters Fri then exiting FL Sat. High pressure builds in over
the Gulf region Sun-Mon then slips out over the Atlantic Tue.


While dry air continues for the next day or there will be enough
low level moisture to preclude any low RH concerns and to support
some patchy fog inland tonight. A front brings in showers and
storms for Fri...ending Sat as very dry air filters in as high
pressure builds into the Gulf region.


.Preliminary Point Temps/PoPs...
TPA  65  81  69  80 /   0   0   0  20
FMY  64  85  68  84 /   0   0   0  30
GIF  61  84  65  84 /   0   0   0  30
SRQ  64  80  70  80 /   0   0   0  20
BKV  57  82  64  80 /   0   0   0  20
SPG  67  79  70  79 /   0   0   0  20


Gulf waters...None.


MID TERM/LONG TERM/DECISION SUPPORT...57/McMichael is the U.S. government's official web portal to all federal, state and local government web resources and services.