Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 252329
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
729 PM EDT Thu May 25 2017

.UPDATE...
Water vapor imagery showing dry air aloft over the region as
weak surface high pressure area settles into the E Gulf
filtering in much drier dewpoint airmass over the FL
Peninsula. Early look at TBW sounding showing very dry air
above 5kt ft inversion with westerly flow through the column.
Expect slightly cooler than seasonal average overnight temps
with clear skies and light winds for pleasant conditions.
Latest grids and forecast on track.

&&

.AVIATION...
VRF conditions all TAF sites all night and Friday with light
winds while residual SCT_BKN clouds over SW FL to thin and
move SEward this evening.

&&

.Prev Discussion... /issued 214 PM EDT Thu May 25 2017/

SHORT TERM (Rest of today - Friday)...
An upper level ridge reaches from Mexico to Hudson Bay while a low
aloft OH troughs southeastward...across the Mid-Atlantic coast then
arcs back to northern FL. Surface high pressure centered over the
northern half of the Gulf of Mexico ridges north through the
Mississippi Valley and a front across the south half of the Gulf
extends across south-central FL to the Bahamas.

With time - The upper ridge slides out over the western Gulf and
stretches to Ontario while the upper low tracks to the Canadian
Maritimes and takes the trough with it...although a weak short wave
trough hangs back across northern FL. The Gulf high pressure tracks
to FL with the front moving into far south FL tonight then south of
there Fri.

For this afternoon - A few showers remain in the far south but will
clear before evening. Considerable cloudiness continues but
will give way to clear/mostly skies after sunset. The
robust and gusty winds of this morning continue to diminish.

The weak short wave trough has very little impact as the deep layer
ridging sliding toward the area from the Gulf dominates. A stable
warm and dry air mass prevails. Model PWAT values run around 0.5
inches for the northern 2/3s of the area and around 1 inch in the
south. Light flow gives way to onshore flow in an afternoon sea
breeze. Temperatures overnight will be below normal but warm back to
near normal by the afternoon.

LONG TERM (Friday Night - Thursday)...
Mid level ridging will build in over the Gulf on Saturday and then
shift east over the state on Sunday as an attendant surface high
across the central peninsula on Saturday sinks south to the southern
peninsula on Sunday. A dry subsident air mass under the deep layered
ridging will support ample sunshine across the entire forecast area
through the long holiday weekend with temperatures warming into the
lower to mid 90s over interior locations each afternoon, with upper
80s to around 90 along the coast due to the sea breeze, with lows
generally in the upper 60s to lower 70s.

During late Monday through Thursday the upper level ridge will shift
east into the Atlantic and will become aligned southwest to
northeast from the south Florida peninsula into the western
Atlantic, as the surface high sets up from the western Atlantic west
across the south-central peninsula. A southeast wind flow albeit
light around the surface high will allow for a slow increase in
moisture across the region through the period which will lead to
increasing chances (Pops 20 to 30 percent on Tuesday, then 30-50
percent Wednesday and Thursday) for diurnal sea breeze driven
showers and thunderstorms each day during the afternoon and early
evening hours with the highest rain chances expected over inland
sections each afternoon as the east and west coast sea breeze
boundaries move inland.

Temperatures will range from the upper 80s to around 90 along the
coast, and lower 90s inland each day, with overnight lows mainly in
the lower 70s.

&&

MARINE... Robust winds continue to diminish although small
craft should exercise caution for the rest of the afternoon.
High pressure in the Gulf moves over FL then meanders there
into the middle of next week with light winds dominated by
afternoon sea breezes.

FIRE WEATHER...
High pressure builds in with a dry air mass...mainly Fri and Sat.
The minimum RH drops below 35 percent Fri and Sat afternoons but
with only limited durations and with low ERC values Red
Flag criteria is not expected to be reached. Moisture begins
to return Sun with no low RH concerns anticipated for the
next few days.

&&

.Preliminary Point Temps/PoPs...
TPA  69  87  70  88 /   0   0   0   0
FMY  70  91  72  93 /   0   0   0   0
GIF  65  91  67  94 /   0   0   0   0
SRQ  69  83  69  88 /   0   0   0   0
BKV  58  87  59  90 /   0   0   0   0
SPG  71  85  73  87 /   0   0   0   0

&&

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

$$

UPDATE/AVIATION/MARINE...25/Davis
UPPER AIR...27/Shiveley
DECISION SUPPORT...69/Close



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