Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 271128
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
628 AM CDT Thu Apr 27 2017

.UPDATE...
FOR 12Z AVIATION DISCUSSION.

&&

.DISCUSSION...

An active period will continue for Middle Tennessee. A line of
showers is currently making its way across the area. These showers
and possible a stray storm will linger after 12z on the plateau.
Overall, today will be a pleasant day as sunshine should breakout
this afternoon. The comfortable conditions will not last long.

Friday and Friday night will be a tricky forecast. It has the
potential to be an impactful event or just a muggy night. When we
wake up Friday morning, dew points will be around 50. Moisture
will quickly return during the day and by Friday evening dew
points will be in the mid and upper 60s. PWAT values will climb to
around 1.5 inches as well. GFS and Euro break out storms
particularly in the NW in response to isentropic lift. At the same
time, height rises will be occurring as upper high centered off
of the Carolina coast strengthens. NAM is not on board with storm
development and keeps the entire area dry Friday and Friday night.
Given the persistence of the GFS and Euro, leaned toward that
solution. If storms are able to fire, favorable thermodynamic and
shear profiles will allow for storms to reach severe limits. Large
hail and damaging winds will be the main threat but cannot rule
out a tornado threat given 0-1 SRH values greater than 250 m2/s2
after 00z. Along with the severe threat, heavy rainfall could pose
a localized flood threat as well. The northwest part of the CWA
has the greatest potential of seeing the storms and heavy rain.
Overall, a lot of uncertainty still exists with this timeframe.

Saturday will be the warmest day of the 7 day period. If you
decide to go for a jog Saturday morning, temperatures will start
in the upper 60s and quickly climb into the 80s with dew points in
the mid 60s. A couple of isolated storms cannot be ruled out
during the afternoon. Any storms that are able to develop have the
potential to be strong to severe with damaging winds and large
hail being the threats.

A more organized system will affect the area beginning Sunday
afternoon. A large trough/ upper low will slide northeast across
the central plains during the day dragging a cold front toward
Middle TN. Models tend to agree that the western part of the CWA
will see rain and storms before 00z Monday. Ahead of the line,
PWAT values will range between 1.5 and 1.75 inches which
translates to more heavy rain. Once again, a localized flood
threat is possible, but the progressive motion of the storms will
prevent a more widespread problem. Areas closer to the Tennessee
River will have the best chance of seeing storms reaching severe
limits. Damaging straight line winds should be the main threat
given the linear nature of the forcing. GFS and Euro weaken the
line as it sweeps across the rest of the CWA Sunday evening and
night.

Next work week should start out mainly dry although some
lingering shower activity cannot be ruled out over the plateau to
start Monday. Rain chances return Wednesday/ Wednesday night
although GFS and Euro are not agreeing with the magnitude and
placement of the QPF.

&&

.AVIATION...
12Z TAF DISCUSSION.

Weak cold front will move across airports early in the TAF period
with a few lingering showers. MVFR cigs and gusty west winds
expected this morning, before VFR conditions return and winds
diminish in the afternoon/evening.

&&

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

&&

$$

DISCUSSION......Reagan
AVIATION........Shamburger



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