Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 250916
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
416 AM CDT WED MAY 25 2016

.SHORT TERM...
(Today thru Fri Night)

Monitoring current regional radar, surface observations, and IR
satellite imagery trends, and continue to believe that isolated
light showers will move across locations generally along and
northwest of a Waynesboro, to Smyrna, to Celina line through the
mid morning hours. Outflow boundaries associated with yesterday
evenings convection across western TN could play a key role in
development of convection across western portions of the mid state
from the mid morning hours onward, as diurnal heating influences
begin to kick in. Thus, mentioned a chance of moderate showers
with thunderstorms across western portions of the mid state mid
morning hours into the afternoon hours, as one of the more
pronounced weak shortwave passages aloft moves across the mid
state region. For the rest of the mid state today, there will be
a slight chance of light showers and thunderstorms from the mid
morning hours onward.

But like yesterday at this time, although as this summertime weather
pattern itself could be considered somewhat "straight forward", once
again getting into particular location details/specifics can definitely
lead to quandaries abounding thru Fri night. Model consensus still
showing the best chance for convection thru Fri night across nw portions
of mid state in proximity to expected model shortwave passages. The
potential of model solution convective feedback issues still persists
thru the forecast period though, and this needs to be kept in mind,
i.e. vertical model profiles of temperature and moisture not being
handled correctly by the model solutions, thus developing showers/
thunderstorms where they should not be developing. However, with the
evolution now having occurred to a surface Bermuda high pressure pattern
being in place across the region, and progressive swly flow still
expected to develop across our area as the day progresses, per model
solution consensus still showing this in reaction to deep troughing
developing across the western U.S. as today progresses too, you can not
just not dismiss model convection being depicted to model error(s).
Yet again, like previous model solutions have shown, and with the most
recent ones still continuing this trend, possible multiple model derived
weak shortwave passages in swly flow aloft are expected. No matter what,
the mid state weather pattern will continue to be warm and muggy. Some
keys to more enhanced potential location convective development across
mid state will be local diurnal and orographic effects along with
convection outflow boundaries. This pattern will continue to support
isolated to scattered light to moderate showers along with isolated to
scattered thunderstorms thru Fri night. But otherwise, just as it was
said at this time yesterday and continues to be the case today, there
are no real focusing mechanisms forecasted to be in place, no significant
surface fronts, significant upper level troughing, etc., thru Fri night.
So, again, would not be surprised that it might be drier than the models
are leading us to believe for particular locations across mid state per
above mentioned model convective feedback issue. However, as stated above
also, on the other hand, this is a summer like type pattern for the mid
state, so isolated to scattered convection is certainly not out of the
question either. This summer like type pattern also has the potential
of producing a few strong thunderstorms too, but no organized significant
threat of any severe thunderstorms continues to be expected. Likewise,
a few of these thunderstorms could produce some moderate, to even locally
heavy, rainfall amounts in short periods of time, in this moisture rich
air mass that will persist across the mid state thru the period, but no
organized heavy rainfall/flooding potential continues to be expected also.

As for temps, they will continue to generally trend 5 to 8 degrees
above seasonal normal values. Highs will generally be in the mid
to even upper 80s, mid 80s Cumberland Plateau Region. Lows during
this period will continue generally spanning the 60s.

.LONG TERM...
(Sat thru Tue)

A warm and humid pattern will be in place through the Memorial Day
weekend and beyond. Temperatures will be 5-8 degrees above normal,
with lows mostly in the mid 60s and highs in the mid to upper 80s.
The Plateau will be mostly lower 60s and lower 80s. There will be at
least small chances for showers and storms each day. We do not
expect any severe storms.

Early Saturday, a high amplitude pattern will be in place with a
ridge centered along the Mid Atlantic coast and a trough over the
Plains. An axis of deep moisture will exist across the Ms Valley,
and the eastern fringe of this moisture will bring a chance for
showers and storms to Mid TN, mainly to our western counties.

Late Saturday through Sunday, the Plains trough will lift out, and
the eastern ridge will expand back across the mid and lower Ms
Valley. This will turn up the heat a little more, and limit any
thunderstorms to 20 percent or less coverage. One feature of
interest is the potential tropical low pressure system that may
stream deep moisture into the Southeast and Mid Atlantic coastal
states this weekend. There is a lot of uncertainty about this
system, and at this time, it appears any impacts will stay to our
east.

For Memorial Day through Tuesday, the upper ridge will weaken
slightly, allowing a little more coverage of thunderstorms. The air
mass will not change, with warm and humid conditions remaining.
Also, we will need to watch for intrusion of possible tropical
moisture from the southeast.

&&

.AVIATION...
06Z TAF DISCUSSION.

Complex back along the Mississippi River beginning to wind down as
upper ridge just too strong for it to buck. Do expect an outflow
to be laid down for later convective development during the day
Wednesday that will likely affect the Clarksville and Nashville
terminals with the potential for a thunderstorm or two. Otherwise
vfr through the period.


&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      87  67  89  68  88 /  40  20  20  10  20
Clarksville    85  65  86  66  84 /  40  20  30  20  30
Crossville     83  63  85  64  84 /  20  20  20  10  20
Columbia       87  65  88  67  86 /  40  20  20  10  20
Lawrenceburg   87  65  88  67  86 /  40  20  20  10  20
Waverly        86  66  87  67  84 /  40  20  20  20  30

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

DISCUSSION......31
AVIATION........13



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