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

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000 FXUS64 KMRX 302007 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 307 PM EST Wed Nov 30 2016 .SHORT TERM (Tonight through Friday)...
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The big event is winding down rapidly. Drier air moves in this evening. Will carry low pops early in the first period although that may be too much. But from Thursday through Friday, dry zonal flow will predominate as Great Lakes upper low slowly lifts ENE; thus seasonable temperatures and dry weather are expected. .LONG TERM (Friday night through Wednesday)...The low amplitude ridge continues east across the Southern Appalachian region Friday night through Saturday keeping much of the region free from precipitation. However, the next system in the pipeline will be swinging through Northern Mexico on its way into Southern Texas over the weekend and northeast through the Ohio Valley Monday night through Tuesday night. So, the polar jet is becoming increasingly active across the Southeastern United States with the rather late change in weather to more of a typical late Fall regime. As the Mexico and Southern Texas upper low edges northeast, the strengthening mild southerly flow will spread deep moisture northeast over the top of a cooler surface airmass in place over the Southern Appalachian region. Showers will be building into the forecast from southwest to northeast late in the day Saturday through Saturday night. Typically, with some chilly air entrenched across the extreme northeastern corner of the viewing area; including parts of Southwest Virginia and Northeast Tennessee, precipitation that falls into a lower (briefly subfreezing) airmass, some snow or mixed precipitation could mix with the rain for a short time late Saturday night into Sunday morning. As the upper level system drives northeast Sunday through Tuesday with a surface reflection riding northeast along the same track, warmer air removes the threat for any winter type precip with another extended period of welcome rainfall expected across the forecast area. It must be stated, there are still differences in the ECMWF and the GFS with this first half of the new week system. The ECMWF is stronger with a closed upper low and associated surface low pressure center which brings a better chance of rain along with more rainfall when compared to the less amplified GFS. The superblend concept trends a little closer to the more aggressive ECMWF forecast with this forecast issuance. The region could be between weather systems around the Tuesday into Wednesday timeframe with lower probability of precipitation for showers. However, the next upper level trough and healthy surface frontal system could be moving into our forecast area by Wednesday night with more widespread showers spreading in ahead of the system cold front. The forecast starts out seasonally cool with max and min temperatures near to just a little below normal over the weekend with a very gradual warming trend into the middle of next week; with the gradual aspect due to the lengthy period of cloud cover and periodic rainfall.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 41 56 34 58 / 10 0 0 10 Knoxville McGhee Tyson Airport, TN 41 53 33 53 / 20 10 0 10 Oak Ridge, TN 41 53 33 54 / 10 0 0 10 Tri Cities Airport, TN 39 50 30 49 / 30 10 10 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...None. TN...None. VA...None.
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&& $$ GC/TH

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