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

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FXUS64 KMRX 210741

Area Forecast Discussion
National Weather Service Morristown TN
341 AM EDT Wed Mar 21 2018

.SHORT TERM...(Today and Tonight)...
Low pressure system is spinning around just north of our area and
bringing in wrap around moisture. Radar returns are showing areas
of higher reflectivity where moderate snowfall is occurring and
causing temperatures to drop several degrees lower than previously
forecasted. Some locations are picking up around half an inch in
in these snow bands, while only 1 or 2 counties away barely
anything is falling. Due to the recently warm ground temperatures
the snow is struggling to stick to the roads, with mostly
rooftops and grassy surfaces able to actually accumulate snowfall.
Expect this trend to continue overnight, but snowfall rates look
to be slowing down a bit as we move into the early morning hours.
Overall the snowfall totals are mostly intact from previous
forecasts with some additional snow accumulations added in the
Northern Tennessee Valley through early this morning.

Expect the precipitation to continue through today, but as
temperatures warm we should see less snow and more drizzly rain
during the daytime hours. The higher elevations are still expected
to remain at or below freezing and could see significant
accumulations with this northwest flow event. We should see
widespread temperatures at or below freezing once again tonight,
but most of the precipitation should be out of the area, so am
currently not expecting much if any additional snowfall tonight in
the Valley once temperatures begin to drop again.

.Long Term (Thursday through Tuesday)...Dry northwest flow aloft
with surface ridging for Thursday and Friday will keep the area dry
and cooler than normal.

For Friday night and Saturday and upper level trough and strong
cyclo-genesis will move into the central plains. This will pull the
boundary layer winds to the south with increasing isentropic lift
across the area. Rain will spread north across the area with the
temperature profile supporting snow over parts of southwest Virginia
and far northeast Tennessee and Smoky Mountains early Saturday
morning. Light snow accumulations are possible across the higher

The upper short-wave will move across the Tennessee Valley and
southern Appalachians Saturday night and Sunday morning keep
likely chances of showers going.

For Monday and Tuesday, upper flow become southwesterly with a
series of jet streaks enhancing periods of rain over the Tennessee
Valley and southern Appalachians. Locally heavy rainfall is possible
as PW increase well above climatology.


Chattanooga Airport, TN             48  32  55  38 /  10   0   0  10
Knoxville McGhee Tyson Airport, TN  40  30  50  34 /  50  20   0  20
Oak Ridge, TN                       41  29  52  34 /  50  10   0  20
Tri Cities Airport, TN              39  27  47  29 /  80  40   0   0


TN...Winter Storm Warning until midnight EDT tonight for Blount Smoky
     Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Southeast

     Winter Weather Advisory until 11 AM EDT this morning for
     Campbell-Claiborne-Morgan-Scott TN.

VA...Winter Storm Warning until midnight EDT tonight for Wise.

     Winter Weather Advisory until midnight EDT tonight for Lee-



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