Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 171131
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
531 AM CST Sun Dec 17 2017

.UPDATE...
FOR 12Z AVIATION DISCUSSION.

&&

.DISCUSSION...

Several things going on at forecast time, but we`ll start with this
system that is quickly closing in on Middle Tennessee.  Latest radar
trends show that rains are moving in much earlier than any model is
suggesting.  For this reason, I have added in definite PoPs west of
I-65 prior to 6 am.  Rains will continue to spread across the rest
of the mid-state through the morning hours and everybody should see
some rain from this system.  That said, it really shouldn`t be all
that much.  Totals will likely range from a tenth of an inch for our
counties nearest the KY state line to a half inch for counties along
the AL state line.  This afternoon, rains will taper off from west
to east and while the heaviest rains will end rather quickly, we
could be dealing with some lingering drizzle through the night and
into the Monday morning commute.  Nothing of any significance on the
whole but there will likely be some reduced visibilities across the
area.  We`ll dry out during the day Monday, but I don`t expect much
sun, so I`m going to back off on forecast highs Monday afternoon
just a bit.

The second system of this forecast will begin moving into Middle TN
Tuesday morning, spread across the mid-state through the day and
provide us with good rain chances and rainfall totals through
Wednesday morning. While the higher totals are expected to be south
of I-40, models are still a little out of agreement regarding the
path of the surface low.  The Euro would suggest a more northerly
trajectory and higher rain totals versus the GFS.  The NAM kinda
falls in the middle of the other two.  So, I`ll carry higher PoPs
for the southern half of the area, but there could be a fairly
significant gradient from north to south as to who sees rain and
who doesn`t.

Wednesday night and Thursday should be dry, but our third system of
the week (which models have been persistently portraying) should
move in Friday and bring us rains through Saturday morning. Storm
total rainfall should be as much, if not more, than the Tuesday
system. This system should be fairly dynamic. Colder air is being
progged to fill in behind the precipitation and while I`m nowhere
near ready to talk winter precip, I can tell you, only one long
range model is suggesting any frozen stuff. For now, I`ll just
carry a small PoP on the backside of the Friday/Friday night
system and leave it all liquid.

The last recorded rainfall at Nashville airport was back on December
5th. While today`s rainfall isn`t going to go far to relieve us from
this latest snap of dry weather, we will make up for it through the
rest of this week.

&&

.AVIATION...
12Z TAF DISCUSSION.

BNA/MQY/CKV/CSV...A shortwave approaching Middle Tennessee from
the southwest is just now beginning to spread light rain into the
region. Expect the showers to grow heavier during the next few
hours, with ceilings gradually lowering to MVFR later this morning
and afternoon. Even though the showers will exit the mid state
during the afternoon, drizzle and fog will develop by evening,
with ceiling & visibility concerns lasting through the night, and
LIFR conditions setting up at CSV after 00Z.

&&

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

&&

$$

DISCUSSION......Unger
AVIATION........08



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