Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 160804
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
304 AM EST Mon Jan 16 2017

.SYNOPSIS...
08Z water vapor and H4 RAP analysis shows a complex mid/upper
synoptic pattern across North America early this morning. Instead
of trying to describe each little feature...I will simplify things
to our local region which resides underneath well-defined upper
ridging. Despite what is occurring elsewhere across the
country...this ridge will not budge during the next several
days...and will control our weather keeping the forecast dry and
warm. The 00Z KTBW sounding continues to clearly show the
influence of this ridging with a strong subsidence inversion
located around 800mb...with a very dry column above this
level...and trapped Atlantic moisture and easterly flow beneath.
In the very upper levels above 300mb we see an increase in
moisture related to arriving southern stream moisture that is
clearly visible in early morning WV imagery. This moisture is
visible in the form of high level cirrus. However...NWP moisture
profiles and simulated satellite products all show the majority of
this moisture and associated jet dynamics shifting through and
east of the area by the later morning hours.

At the surface...As mentioned above, our forecast area is dominated
by synoptic easterly flow to the south of a ridge center along the
eastern seaboard. This ridge will be migrating east and southeast
during the next 24-36 hours...allowing our winds to shift to a more
southeast and eventually southerly direction in the lower levels.

&&

.Short Term (Today through Tuesday)...
Kind of a "broken-record" forecast through the early portion of the
week. Subtle differences each day with regards to wind direction and
temperatures...but the forecast can be generalized as fair (rain-
free) and warm.

The upper ridge in place overhead today will only strengthen/amplify
further tonight into Tuesday in response to strong shortwave energy
migrating through northern Mexico and the associated height falls
over the southern Plains. The stronger the ridging aloft...the
warmer the forecast potential given the proper insolation. High
temperatures today will generally end up n the middle and upper
70s...and going along this thinking...Tuesday will likely be a
degree or two warmer...allowing most locations to make a run at the
80 degree mark. Cooler locations likely holding in the mid 70s both
days will be southern Pinellas County and the Island/capes of
Charlotte Harbor due to the influence of the water under E/SE flow.

As mentioned above...the forecast is dry. The upper ridge will
provide plenty of synoptic suppression...with the Atlantic moisture
trapped underneath...remaining too shallow for any measurable
shower activity.

While the upper cirrus is likely to hold back the fog potential
early this morning...a better atmospheric potential setup for
patchy/areas of late night fog will occur tonight. While a
widespread dense fog event is not anticipated at this point...this
increased fog potential if shown by the SREF and several statistical
MOS products.

&&

.Mid Term/Long Term...
Surface high pressure will be in control of the weather across west
central and SW Florida at the start of the forecast period. This
will keep the above normal temps in place along with limited rain
chances. The only major weather feature in the extended will be the
progression of a frontal boundary through the region. Models
continue to depict lee-side cyclogenesis occurring in the Central
Plains as jet energy moves into the southwestern U.S. later this
week. Although some timing differences remain, models have become
increasingly confident on this low pressure system pushing into the
Missouri/Ohio River valleys allowing troughiness to develop across
the eastern U.S. late this weekend and early next week. Once again,
there remain some discrepancies with respect to timing and amplitude
of this feature but nevertheless this appears to set the stage for a
decent shot at rain for the area.

Mid/upper level dynamics at the present appear favorable for
thunderstorms with this FROPA, perhaps some strong, so have
introduced tstms into the forecast beginning Sunday continuing into
Monday next week. Given the uncertainty this far out, it is likely
that some temporal changes will be needed to the forecast over the
coming days. Stay tuned.

&&

.AVIATION (16/06Z through 17/06Z)...
General VFR conditions are expected through the TAF period across
west-central and southwest Florida. Some potential for a brief
period of MVFR vis around KLAL/KPGD in the few hours surrounding
sunrise...however...this potential appears to be decreasing.
Expect a sct-bkn stratocu deck through much of the period with
bases between 4-6kft feet. Light easterly winds shift southeast
during the afternoon and then back to east toward sunset this
evening.

&&

.MARINE...
High pressure centered over the eastern seaboard and western
Atlantic will remain in control of the forecast waters through the
next several days as it slowly migrates east and southeast. Easterly
winds today will slowly shift southeast on Tuesday. The ridge axis
will eventually move over the region during Wednesday. Winds through
the middle of the week remain generally under 15 knots...and even
light and variable near the coast each afternoon as weak sea-breezes
attempt to develop. The next potential for elevated wind and/or
inclement weather over the eastern Gulf of Mexico will not arrive
until Friday.

&&

.FIRE WEATHER...
No significant fire weather concerns are expected through the next
several days. Increasing low level moisture will keep relative
humidity above critical levels and winds will stay generally light.
Any fire activities near the coast the next several days will need
to take into consideration the potential development of weak sea-
breezes. As the sea-breeze tries to move inland after 1-2 PM...winds
are likely to become light and variable...or light onshore. The next
potential for inclement weather and/or wetting rainfall will not
arrive until at least Friday.

&&

.Preliminary Point Temps/PoPs...
TPA  79  61  78  63 /   0   0   0   0
FMY  79  60  81  61 /  10  10   0   0
GIF  79  58  80  60 /   0   0   0   0
SRQ  77  60  76  59 /   0   0   0   0
BKV  79  56  79  54 /   0   0   0   0
SPG  77  62  76  63 /   0   0   0   0

&&

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

&&

$$

SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WX...Mroczka
MID TERM/LONG TERM/DECISION SUPPORT...McKaughan


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