Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 170741
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
241 AM EST Tue Jan 17 2017

.SYNOPSIS...
08Z water vapor and H4 RAP analysis continue to show an amplified
and rather chaotic upper level synoptic pattern across the conus
early this morning. All we need to know about this pattern in the
short-term across the Florida peninsula, is that we are safe from
any inclement weather under the protective influence of strong
mid/upper level high pressure. Each of the past few days the 00Z
KTBW sounding profile has clearly showed the influence of this ridge
over our heads with a well-defined subsidence inversion around
800mb. This past evening was no exception...with the inversion
located around 790mb...with a very dry atmosphere through the
extent of the column above this level. All the moisture in the
atmosphere is trapped under this inversion in the boundary layer and
delivered across the peninsula within the lower level E/SE flow, on
the south side of high pressure now centered off the Carolina coast.

The ridge over our heads is already strong...but is beginning to
further amplify over the Gulf of Mexico and FL peninsula early this
morning in response to a strong trough pivoting through the SW states
/ Northern Mexico...and the associated height falls approaching the
southern Plains. This amplification only further ensures a
continuation of the dry and warm forecast through the middle of the
week.

&&

.Short Term (Today through Wednesday)...
The simplest way to describe the weather across west-central and
southwest Florida the next couple of days will be benign and warm.
The strength of the upper ridge overhead and associated suppression
will keep the column very dry and prevent any chance of synoptic
precip...and the trapped moisture below the subsidence inversion
will simply be too shallow to support any real chance of isolated
migratory diurnal sprinkles.

The surface ridge currently off the Carolinas has been slowly
slipping southward over the past 24 hours...and this trend will
continue...bringing the ridge axis directly over the FL peninsula by
later through Wednesday. As the ridge axis arrives
overhead...boundary layer flow from the E/SE will really slacken.
The lack of this defined flow, combined with the strong terrestrial
heating should actually result in generally light, but well-defined
sea-breeze circulations developing near the coast each of the next
two afternoons. The developing flow off the relatively cooler shelf
waters will keep temperatures during the mid/late afternoon a bit
cooler at the beaches than they will be several miles inland. Well
defined sea-breezes are not exactly a normal occurrence for our area
in January, but here we are.

High temperatures through the short-term will be in the upper 70s to
lower 80s away from the coast...and generally middle 70s near the
coast. Some coastal spots may briefly get into the upper 70s before
the sea-breeze kicks in and drops temps a bit. Also, immediate
coastal locations to the north of Pinellas County may drop back down
to near 70 (or even upper 60s) after reaching their high temp, due
to even cooler average shelf waters along the Big Bend region.

&&

.Mid Term/Long Term...
A somewhat unsettled weather pattern is expected later this week and
into the weekend. A weak shortwave will move across the Deep South
as a weakening surface boundary stalls north of the area Friday into
Saturday. The presence of this boundary will support rain chances
Friday and Saturday, especially from the Bay Area north with the
Nature Coast expected to have the best rain chances at this time.

On Sunday, models continue to show a low pressure system pushing
into the Tennessee/Ohio River valleys allowing a significant trough
to develop across the eastern U.S. late this weekend and early next
week. This will allow for a front to move through the region Sunday
into Monday bringing some much needed rainfall to our area. Forecast
model soundings continue to support favorable mid/upper level
dynamics and sufficient CAPE for thunderstorms with this front as it
moves through the area, perhaps even some strong to severe storms.
Will have to see how future model runs handle this setup over the
next few days so stay tuned.

Behind the front, cooler and drier air will filter in although temps
are only expected to return closer to climatological norms as no
polar air is associated with this front but we`ll take the "cooler"
weather when we can get it this winter.

&&

.AVIATION...
General VFR conditions at area terminals to start off the 06Z TAF
cycle. SCT-BKN stratocu at times through the morning
hours...mostly above 4KFT. Potential for period of MVFR/IFR BR
between 09Z and 13Z...mainly for KLAL/KPGD. VFR conditions prevail
through the majority of the Tuesday daylight hours. Light E/SE
flow in the morning will shift S/SW during the afternoon at
coastal terminals. Winds become light and variable with sunset
this evening.

&&

.MARINE...
High pressure will slide south over the region today and remain in
place through Thursday. Winds will remain generally below 15 knots
with low seas. Expect winds to become light variable or onshore near
the coast each of the next couple afternoons as a seabreeze
develops. The next potential for inclement weather or elevated winds
does not arrive until Friday. Confidence is increasing in a wetter
and rougher boating forecast during the upcoming weekend over the
eastern Gulf of Mexico.

&&

.FIRE WEATHER...
No significant fire weather concerns expected through the next
several days. Relative humidity remains well above critical
levels...and winds will be generally light. However, one minor
concern might be light winds resulting in low LDSI values on
Wednesday. The next significant potential for any wetting rainfall
does not arrive until late Friday...or this upcoming weekend.

Patchy fog is expected after midnight the next couple of
nights...however no widespread dense fog is anticipated.

&&

.Preliminary Point Temps/PoPs...
TPA  79  63  77  62 /   0   0   0   0
FMY  81  61  80  61 /   0   0   0   0
GIF  81  61  82  60 /   0   0   0   0
SRQ  76  61  75  59 /   0   0   0   0
BKV  79  57  79  57 /   0   0   0   0
SPG  76  63  75  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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