Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 050847

Area Forecast Discussion
National Weather Service Nashville TN
247 AM CST Mon Dec 5 2016


Precip moved out of the area earlier yesterday evening and left
the mid state with cloud cover head of the next shortwave trough.
temperatures should be on the rise for the remainder of the day as
WAA precedes the troughs arrival Tuesday morning. Models seem to
agree that most of the precip will fall during the evening tonight
and overnight into Tuesday morning, with slight chances for
thunderstorms still lingering in the forecast. Models have backed
off on instability a bit, but the shear remains around 50-60 knots
from 0-6km, and with a dynamic upper shortwave, still cant rule
out some thunderstorms this evening and overnight.

Rain chances will continue Tuesday morning, with even some slight
chances for thunder still in northeast zones. As the upper
shortwave moves towards the northeast, rain chances will come to
an end from west to east during the day. By Tuesday evening, a
brief dry period will move into the region ahead of a larger
trough moving in from the Great Plains for the late
Wednesday/Thursday timeframe.

For early Thursday, the GFS and ECMWF have lined up nicely in
regards to upper flow patterns, however they still do not agree on
precip timing and amounts. The GFS has gone much drier than
previous solutions, and the drying trend has now taken out all
mention of precip over the mid state. The ECMWF has also trended
drier, but still places precip over the area Thursday morning. The
biggest change for this event was the ECMWF, which went from a
decent wet solution to nearly dry, so it seems models are trending
drier for Thursday morning. Backed off pops a bit to reflect this,
and if the drying trend continues, we may be just left with a
strong dry cold front to cool off temps later in the week. For
now, have chance pops during the Thursday morning timeframe. Also,
temperatures are cool enough that some snow will mix in, so did
not make any changes to having snow mentioned with the rain where

Thursday night through Saturday still look very cold, with lows
Thursday night behind the cold front hitting the teens for most of
the mid state. Highs on Friday will see about half of the mid
state not getting above freezing, while others just barely get
into the mid 30s. Lows in the 20s Friday night will give way to
some 40s on Saturday thanks to some early WAA ahead of the next
shortwave trough to impact the region.

Both the GFS and ECMWF have changed their solutions for the system
coming in next Sunday. Both have weakened the shortwave a bit, and
significantly warmed the low levels. Still have some snow mention
late Saturday night into Sunday morning, however after that both
models have much warmer air moving in and look to have rain for
the mid state for the duration of the event. WAA will keep temps
above freezing Sunday night and highs will get to the mid 50s on
Monday. Both models also line up well with precip, and have likely
pops Sunday night and into the day Monday. After Monday, however,
the GFS and ECMWF begin to diverge starting with the strength and
amplitude of the next two troughs from next Tuesday through
Thursday, so it will be interesting to see how the next few runs
resolve the model differences.



Just no way around it, it looks like a little bit of improvement
in short term guidance as compared to what was expected prior to
05/00z, but not the best flying conditions expected still thru
06/06Z at terminals across the mid state region. With short term
ceiling and vsby fluctuations ranging from MVFR to LIFR
anticipated, several adms possible thru at least 05/18Z. With a
general continuance of an overrunning pattern in place across mid
state region, low level persistent cloudiness is expected, and
with so much low level moisture trapped below cloudiness, light
winds, and the continuation of favorable dewpoint depressions, fog
formation at all terminals will persist thru at least 05/16Z also.
Potential of light rainfall once again expected across our region
after 05/20Z. A more substantial chance of light rainfall is
expected after 06/00Z as deeper moisture moves into the mid state
region associated with western sfc gulf moisture system moves newd
into mid state region.


Nashville      50  49  56  35  48 /  30 100  70  10  10
Clarksville    48  44  51  32  45 /  20 100  70  10  10
Crossville     51  47  57  35  48 /  50 100  80  10  10
Columbia       51  50  56  35  49 /  50 100  70  10  10
Lawrenceburg   53  51  58  36  50 /  60 100  70  10  10
Waverly        49  46  51  33  45 /  30 100  70  10  10





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