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

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000 FXUS64 KMRX 092021 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 321 PM EST Sat Dec 9 2017 .SHORT TERM...(Tonight and Sunday)... A deep trough to our west will be crossing the area this evening. Radar shows light precip ahead of the trough is beginning to move into the TN Valley, but some dry low level air seems to be evaporating most of it before it reaches the ground. Moisture depth will increase as the midlevel thermal trough moves over the area, producing steep lapse rates that will generate scattered snow showers and flurries. Accumulations will be mainly above 3000 ft as a 25-30 kt upslope flow locally enhances lift in the mountains. 1-2 inches will be possible through midnight above that level, with a half inch or less in the lower elevations of SW VA and NE TN and northern Plateau. Flurries may occur as far south as Dayton and Athens. Decreasing moisture depth and midlevel warming will occur in the 03-06Z time frame as the trough pushes east. Some upslope flurries may persist into Sunday morning for the mountains. Wind chills in the mountains may drop below zero on some peaks, with most spots in the teens to single digits. Sunday will have decreasing clouds with highs in the upper 30s to lower 40s. .LONG TERM...(Sunday night through Friday)... A mostly clear and cold night night sunday night will be followed by a much warmer and dry day Monday as brief ridging flattens out upper trough that has been over the eastern Tennessee Valley the last few days. The upper trough digs southward again late Monday night and Tuesday with a chance for more snow northern and eastern sections of the forecast area. Amounts look to be much smaller than the past days event. Areas in the northern valley may get a few tenths and mountains an inch or two of snow. Highs Monday will warm to the mid 40s to lower 50s but drop 10 degrees to the mid 30s to lower 40s... Tuesday. Another cold night Tuesday night with mid teens to mid 20s and colder northeast with highs mid 20s to mid 30s and around 40 south. The snow will move out with clearing skies. Thursday lower pressure moves into the Tennessee and lower Ohio Valley associated with another cold front with winds switching to the south and southwest and warming temperatures back into the 40s to lower 50s. Because of the warmer temperatures Thursday most of the precipitation will fall as rain initially but change to snow Thursday night and early Friday. Friday precipitation moves out once again with higher pressure settling over the southeast warming temperatures back into the upper 40s to mid 50s the warmest of the week. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 24 43 28 53 / 0 0 0 0 Knoxville McGhee Tyson Airport, TN 22 41 28 50 / 10 0 0 0 Oak Ridge, TN 23 41 28 50 / 10 0 0 0 Tri Cities Airport, TN 23 39 22 48 / 30 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ DGS/TD

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