Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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FXUS64 KMRX 112017
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
317 PM EST Mon Dec 11 2017

.SHORT TERM...(Tonight through Tuesday night)...A fast moving
short-wave will dive southeast across the Ohio Valley tonight
pulling a frontal boundary through the region early Tuesday
morning. The orographic northwest flow will produce snow showers
across much of the higher elevations with the west to northwest
facing slopes of the far eastern Tennessee Mountains picking up up
to 2 inches. Have issued a winter weather advisory beginning early
Tuesday morning through the evening hours.

The northern Plateau and higher elevations of southwest Virginia
will see up to 1 inch, especially High Knob, Virginia. Will issue
a SPS to reflect this concern. Periods of flurries/chance of
flurries elsewhere with little to no accumulations.

High Tuesday will be in the morning with strong cold air advection
and mostly cloudy sky bringing colder temperatures in the
afternoon.

For Tuesday night, breezy conditions and cold temperatures in the
high elevations will produce dangerous wind chills. Wind chills
will likely drop to 5 to 10 degrees below zero across the far
eastern Tennessee Mountains. Will issue a wind chill advisory
there.

.Long term (Wednesday morning through Tuesday)...Northwest flow
will remain over the area through Wednesday as high pressure and
mostly clear skies set in. Temperatures will remain several
degrees below normal as cold air will advect in through Wednesday
night.

By Thursday...low and mid level flow will be near zonal as a trough
deepens over the Great Plains states and moves eastward. A shortwave
moving through that trough will cause enough lift for snow showers
beginning overnight Thursday into the afternoon on Friday. The
entire area could see flurries in the early morning...with areas
along and south of I40 changing to rain by midmorning...and
remaining as rain through the day. Areas along and north of I40...as
well as the pleateau and higher elevations in east TN...will be at
or below freezing...with mostly snow flurries expected. Could see
mixed precipitation in the east TN Valley...with snow predominant
type. The system will move east of the Appalachians by Friday
evening...with northwest flow keeping a chance for snow showers in
the higher elevations into Saturday morning. Strong northwest flow
behind this system will drop temperatures again several degrees
below normal for this time of year.

By Saturday afternoon...low and mid level flow will transition to
out of the west and southwest as a weak ridge builds over the area
ahead of yet another trough developing over the Great Plains states.
This SW flow will bring warm air and moisture to the area through
the day and night. A shortwave moving through this ridge...as well
as upper level divergence associated with a jet streak...will allow
for enough energy to cause showers through the day and overnight
Sunday. PW values are expected to be above the 90th percentile for
this time of year...with moderate rainfall expected.

Monday morning...brief northwest flow will be present with upslope
allowing light snow showers through the morning hours...mainly at
higher elevations in east TN and SW VA. This sytem will move to the
east by Monday afternoon...with high pressure over the are through
Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             37  43  25  43 /  10   0   0  10
Knoxville McGhee Tyson Airport, TN  35  40  22  39 /  10  10  10  10
Oak Ridge, TN                       36  40  22  38 /  10  10  10  10
Tri Cities Airport, TN              32  38  16  33 /  10  30  20  10

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...Winter Weather Advisory from 4 AM to 9 PM EST Tuesday for Blount
     Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Unicoi.

     Wind Chill Advisory from 10 PM Tuesday to 7 AM EST Wednesday for
     Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier
     Smoky Mountains-Southeast Carter-Southeast Greene-Unicoi.

VA...None.
&&

$$





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