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

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000 FXUS64 KMRX 222006 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 306 PM EST Wed Feb 22 2017 .SHORT TERM (Tonight and Tomorrow)...
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Latest water vapor and RAP upper level analysis continues to show rather strong middle level circulation moving eastward across the Northern Gulf of Mexico and Northern Florida. As this feature moves out, Atlantic surface ridge builds westward tonight. Residual low level moisture and calm to very light winds will likely lead to fog across the area, with some locations possibly seeing dense fog during the latter portion of the overnight hours. Shortwave trough aloft will ride east across Kentucky and West Virginia through the day tomorrow. With it, prospects of some light pcpn across the Northern Plateau counties, NE Tennessee, and SW Virginia are possible for the afternoon hours. Any pcpn with this feature should be rather short-lived before the shortwave exits the area to the NE by the evening hours. Temperatures tonight and tomorrow will remain nearly 20 degrees above seasonal normals. This in a month that is already ranking within the top ten warmest Februaries on record for Chattanooga, Knoxville, and Tri-Cities. .LONG TERM (Thursday Night through Wednesday)... Another warm day on Friday with highs topping out in the 70`s and some places will be pushing 80 degrees. In fact we could see all 3 climate sites break record high temperatures for this day, here`s the data for the 24th. Chattanooga: 77 set in 1890 Knoxville: 76 set in 1890 Tri-Cities: 72 set in 1982 This warming will all happen ahead of our next system which could produce severe weather in our area. That system is a low moving across the central plains states and into the Great Lakes region with a cold front being dragged along with it. Increasing southerly winds ahead of the front will bring in warm air and the increasing speed of the low level jet will help produce good shear in our area. 0-1 km and 0-6 km shear values are strong which will help lead to strong winds as the primary severe threat in our area. CAPE values will be pretty good as well (in the 500-1000 J/kg range), but a cap could inhibit some convection from forming ahead of the main line. Biggest threat for our area will be with the main line passing through late Friday night through early Saturday morning. Once the front passes through it will force temperatures to drop and highs on Saturday will be about 15 - 20 degrees colder than they were on Friday, but we will STILL be a few degrees above normal even after this front passes through (going to show how warm we`ve been lately). We could potentially see a light snow flurry or two in the higher elevations Saturday night into Sunday, but minimal accumulations would be expected. Unfortunately many locations will see sub freezing or near freezing temperatures which could kill off early growth due to the recent warm temperatures. We start to warm back up and will see another round of showers early next week.
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Chattanooga Airport, TN 55 73 55 77 / 10 10 10 10 Knoxville McGhee Tyson Airport, TN 53 73 53 76 / 10 10 10 10 Oak Ridge, TN 52 73 53 76 / 10 10 10 10 Tri Cities Airport, TN 49 72 48 76 / 20 20 10 10
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