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

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000 FXUS64 KMRX 210741 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 341 AM EDT Wed Mar 21 2018 .SHORT TERM...
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(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 elevations. 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.
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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
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...Winter Storm Warning until midnight EDT tonight for Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Southeast Monroe-Unicoi. 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- Russell-Scott-Washington. && $$ ABM/DH is the U.S. government's official web portal to all federal, state and local government web resources and services.