Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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489
FXUS62 KTBW 250722
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
322 AM EDT WED MAY 25 2016

.SYNOPSIS...
Aloft - ridging reached from the western Gulf of Mexico to the Great
Lakes while a low in the Gulf of Maine troughed down to east FL
waters and the Bahamas. Surface - high pressure centered just off
the southeast U.S. coast sprawled across most of Florida to the
Gulf of Mexico. An old frontal boundary stretched from the waters
south of the Keys to the Bahamas.

&&

.SHORT TERM (Today through Thursday)...
The upper ridge shifts eastward...from the central Gulf of Mexico
to the eastern seaboard...while the upper low exits into Canadian
waters but leaving the base of the trough east of the Bahamas. The
surface high shifts out over the open atlantic...along 35 north
latitude...as it continues to ridge across FL to the Gulf of
Mexico. A weak inverted trough forms on the this ridge late
Thu...east of the Bahamas. The frontal boundary meanders between
the Keys and Cuba.

The shift eastward of the upper ridge/trough maintains a dry
and stable northwest to north flow aloft. although a narrow plume
of higher moisture air moves across...east to west...the area
later today and reaches as far north as Tampa Bay. The Atlantic
high pressure strengthens and tightens the gradient across the
state with winds robust enough to keep any sea breezes pinned at
or just off the gulf coast. Have opted to keep the forecast rain
free...with the exception of this afternoon from Tampa Bay south.
The higher moisture and some convergence along the sea breeze
boundary will support a slight chance of showers/storms.
Temperatures will in the seasonable range although Thu highs may
be a degree or two cooler.

&&

.MID/LONG TERM (Thursday night through Tuesday)... A potent upper
trough will be positioned across the mid-section of the country at
the beginning of the long range period. further east...weak upper
ridge will extend from the Gulf of Mexico into the western Atlantic.
Within this area of high pressure, a weakness will exist...as a
broad cutoff low develops from the Bahamas into the western Atlantic
ocean. This feature will be the primary focus through the medium to
long range period.

From Thursday into the upcoming weekend, expect a fairly seasonal
weather pattern. The surface ridge axis will extend from the western
Atlantic into southern Georgia/northern Florida. This will allow for
persistent east to northeast low level winds, prompting low level
moisture to gradually increase late this week into the weekend. This
would tend to favor increased afternoon showers and storms along the
seabreezes. One fly in the ointment will be the development of a
weak upper low over the Bahamas and western Atlantic. This feature
is poised to move slowly northwestward toward the southeast U.S.
coast into the Memorial Day weekend. The placement of this low will
greatly influence coverage of showers and storms. Models currently
depict a ribbon of dry mid-tropospheric air and weak subsidence
across the Florida peninsula, which could limit overall convective
coverage.

As we move into the first half of next week, things get a bit more
interesting with respect to the previously mentioned upper low. Long
range solutions continue to bring the low northwestward to near the
South Carolina/Georgia coast by Monday. Several solutions depict an
area of low pressure may develop along the southern and eastern
periphery of the low and revolve northwestward into the southeastern
states Monday or Tuesday. While some tropical/subtropical
development appears possible, the National Hurricane Center is only
showing a low chance of development over the next several days. This
will be something to watch closely as we head into the holiday
weekend. Regardless, portions of the southeast U.S. look to receive
some fairly heavy rainfall, as a deep plume of moisture will move
inland. At this time, this area looks to remain north and east of
west central and southwestern/central Florida. Despite residing west
of both upper and low level low pressure centers, moisture will
remain adequate for the usual daily afternoon showers and
thunderstorms throughout early next week. Should the upper low
and/or surface low take a more southerly track, greater rain chances
would surely be needed.

Temperatures looks to remain near seasonal averages, with daytime
highs in the upper 80s to low 90s, and lows around 70 degrees each
night.
&&

.AVIATION...
25/07Z-26/06Z. VFR with FEW-SCT clouds...LCL BKN. ISOLD SHRA/TSRA
late afternoon near the coast but little if any impact at the
terminals. Winds prevailing east or ne and robust afternoon and
early evening.

&&

.MARINE...
Atlantic high pressure ridges into the Gulf through the week with
a tightening gradient and east or northeast winds. This will
result in limiting any sea breezes plus provide some evening and
late night surges of up to 20 knots. A trough of low pressure is
forecast to form on the south side of the ridge...northeast or
east of the Bahamas during the weekend...with winds becoming more
northerly. limited showers and thunderstorms for the next couple
of days will increase for the end of the week.

&&

.FIRE WEATHER...
High pressure continues across northern Florida through the
week...with a trough of low pressure forming northeast or north of
the Bahamas during the weekend. Showers and thunderstorms will be
limited for the next couple of days but increase toward the
weekend as moisture returns. Relative humidity values will briefly
approach 35 percent in isolated locations mainly north of Tampa
Bay this afternoon and Thu. Some robust transport winds and
efficient mixing will result in high dispersion indices this
afternoon and again Thu.

&&

.Preliminary Point Temps/PoPs...
TPA  89  69  87  70 /  10   0   0  10
FMY  90  68  88  68 /  10  10  10   0
GIF  88  66  85  67 /   0   0  10  10
SRQ  88  68  86  68 /  20  10   0  10
BKV  89  62  86  62 /   0   0   0   0
SPG  89  72  86  72 /  10   0   0  10

&&

.TBW Watches/Warnings/Advisories...
FL...None.
Gulf waters...None.
&&

$$

SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WEATHER...09/Rude
MID TERM/LONG TERM/DECISION SUPPORT...84/Austin



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