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

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000 FXUS64 KMRX 201850 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 250 PM EDT Fri Oct 20 2017 .SHORT TERM...(Tonight and Saturday)...We continue in a rather stagnant pattern and thus another mostly persistence forecast. High pressure at the surface and aloft over the region will be shifting slowly east during the period. The atmosphere will remain on the dry side. Temperatures running slightly higher again today than yesterday, so the gradual warming trend is continuing. Some patchy fog can be expected late tonight especially near bodies of water. Tomorrow will feature plenty of sunshine despite some high clouds and temperatures generally near or a bit higher than today. .LONG TERM...(Saturday night through Friday)...By Saturday evening the upper ridge moves off the southeast U.S. coast. Meanwhile, a deep long wave trough and associated cold front will move across the Midwest. So, expect dry conditions across the forecast area with prefrontal warming bringing temperatures on Sunday 5 to 10 degrees above normal. The high amplitude trough will slow forward/eastward progress of the entire system. Showers and thunderstorms will remain over West Tennessee for much of Sunday and early Sunday night. Eventually, a closed upper low forms over northern Mississippi early Monday morning. This is where the forecast gets difficult due to location and evolution of this closed low. Current model progs are having a tough time not just with timing but also location. Should the low dive into central Alabama the highest QPF will occur over the southern TN Valley. Downsloping winds from the east/southeasterly wind component would limit heavy rainfall over northeast TN...say from Knoxville east along and north of I-40 and the I-81 corridor. This upper low is kicked out rather quickly with another following in its wake by Monday night. This will bring significantly colder air to the region on Wednesday into Thursday. In fact, some higher elevations could see snow, perhaps mixed with rain, across northern parts of Tennessee, mountains of southwest Virginia and the Appalachians. Precipitation chances diminish by Wednesday night. The remainder of the week will be below normal with another trough expected to produce more precipitation by early next weekend. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 49 79 56 77 / 0 0 0 10 Knoxville McGhee Tyson Airport, TN 49 77 52 78 / 0 0 0 10 Oak Ridge, TN 49 78 51 77 / 0 0 0 10 Tri Cities Airport, TN 44 78 47 76 / 0 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ LW/AC is the U.S. government's official web portal to all federal, state and local government web resources and services.