Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 231144
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
644 AM CDT Tue May 23 2017

.UPDATE...
FOR 12Z AVIATION DISCUSSION.

&&

.DISCUSSION...

As part of a system that is plaguing the Gulf States with some heavy
rain, we have a few showers streaming northward across the mid-state
at forecast time.  These showers will continue to push across the
area and should leave Middle TN by mid-morning.  An isolated shower
isn`t out of the question this afternoon, but the bulk of the
activity will likely be saved for this evening, overnight and into
the day on Wednesday as our next widespread weather maker starts to
move into the region.

A fairly expansive longwave pattern over the eastern half of the
CONUS will drive our weather for the next couple of days.  Of more
importance will be the closed low currently taking shape over the
Upper Mississippi Valley.  This low will dive southward over the
next day or two and as it does, a surface trough will round the base
of it.  This trough will bring showers and scattered thunderstorms
into Middle TN tonight.  Forecast soundings show some instability
overnight, however, organizing shear should be relatively lacking.
For this reason, I don`t expect to see any severe weather.

On Wednesday, the trough moves on and the closed upper low should
push south through the mid-state towards the Alabama state line.  As
it moves over Middle TN, temperatures aloft get really cold.  -18
degrees at 500mb, decent mid-level lapse rates and deep layer shear
values of 35-40 kts means that a few small hail-producing
thunderstorms will not be out of the question.  However, they should
remain sub-severe.

By Wednesday night/Thursday morning, the upper low starts to pull
away from Middle TN.  It will likely leave clouds and some light
rain in its wake.  Will hold onto at least chance PoP for the
eastern half of the mid-state through Thursday.  Because of the
lingering cloud cover, I`ll also need to run above guidance for
Thursday morning lows and below guidance on Thursday afternoon
highs.  Got that?

We`ll dry out once again on Friday, but we should warm nicely as the
sun comes out and temperatures climb into the 80s.

The potential for weekend rain is still "up in the air".  Most of
Saturday still looks dry, but models are starting to zero in on
increased chances of rain Saturday night and Sunday.  Will increase
PoPs starting Saturday afternoon though there is still some uncertainty
in this portion of the forecast, but it could be wet by Saturday
night and Sunday. Temperatures should still remain above normals
through the weekend.

&&

.AVIATION...
12Z TAF DISCUSSION.

VFR conditions look to prevail for most of this TAF period, with
isolated showers possible during the day. Current radar shows
scattered showers which will mainly impact KCSV but also have VCSH
at KBNA this morning as well. Chances for rain look to increase
during the evening and overnight hours into Wednesday, so have
prevailing showers at all terminals at the end of the TAF period.
At KCSV, models want to drop cigs to IFR after 09Z, but KBNA and
KCKV look to be MVFR among model consensus before 12Z Wednesday.
Winds look to remain light through the TAF period as well.

&&

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

&&

$$

DISCUSSION......Unger
AVIATION........Barnwell



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