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

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000 FXUS64 KMRX 090830 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 330 AM EST Fri Dec 9 2016 .SHORT TERM (Today and Tonight)...
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Strong cold air advection is occurring across the area behind a departing cold front. The cold front is now well to the east along the Eastern Seaboard. Seeing some clouds build into the area from the north with most of the cloud cover remaining north of I-40. The moisture is shallow with the arctic airmass in place but the moisture has been sufficient enough in a few locations, to the north, to produce some flurries. Due to this, added the possibilty of a few flurries across portions of SW VA and NE TN through mid- morning. Northerly winds also remain up behind the boundary and temperatures have remained in the mid to upper 20s throughout most of the night with the increase in cloud cover and winds. Expect morning lows in the teens will be possible in the sheltered valleys this morning. Clouds will break up late this morning with mostly sunny skies expected today. Despite the sunny skies, temperatures will only rebound into the upper 20s to upper 30s with the heart of the arctic airmass overhead. Dewpoints today will mix out into the upper single digits and teens with surface high pressure moving in from the west. The combination of these factors will set the stage for the coldest night of season. The atmospheric cooling processes will switch from cold air advection to radiational cooling tonight. Light winds and clears skies will lead to ideal radiational cooling conditions. Temperatures will drop quickly after sunset with temperatures in the teens throughout much of the area by Saturday morning. .LONG TERM( Saturday through Thursday)... Will remain in a quiet weather pattern Saturday and Sunday with surface high pressure shifting east across the region and flow aloft becoming zonal. Will move into an unsettle pattern Sunday night into Monday as a a cold front moves in from the west. A strong 850 MB jet will accompany the front and should see winds...especially over higher elevations ...increase...becoming breezy to windy Sunday night. the front moves into the area....widespread rain will push through. Could see a brief rain/snow mix late Sunday night as overnight temperatures drop near freezing over higher terrain. Scattered light rain will linger into Monday night with a transition to light snow or flurries across high elevations as cooler air filters into the region. Model consistency decreases and shows significant differences Tuesday and Wednesday...and confidence remains quite low for this time frame. The GFS puts us between systems on Tuesday with the a cold front moving in for Wednesday. The ECMWF lifts an area of low pressure in from the south on Tuesday for another round of mainly rain with a weaker version of the cool front pushing through Wednesday. Will keep pops at 20 to 40 for now. Cooler air moving in with the cold front will slowly transition the lingering rain to snow across area Wednesday night. Cool surface high pressure builds in behind the system for a dry Thursday.
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Chattanooga Airport, TN 38 22 45 28 / 0 0 0 0 Knoxville McGhee Tyson Airport, TN 33 20 41 25 / 0 0 0 0 Oak Ridge, TN 35 20 40 25 / 0 0 0 0 Tri Cities Airport, TN 32 15 38 22 / 0 0 0 0
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