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

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659 FXUS64 KMRX 051943 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 243 PM EST Thu Dec 5 2019 .SHORT TERM...(Tonight and Friday)... This afternoon it was sunny with temperatures in the 50s and lower 60s. Winds were light and variable with a couple of locations reporting some wind gusts between 8 and 12 mph. Satellite imagery was showing increasing clouds moving into Middle Tennessee. The next system to affect the region is currently located over the Four Corners. This shortwave will translate quickly across the southern Plains tonight. Overnight winds will gradually shift to the south as the area of high pressure moves off the Carolina coast. Clouds will be on the increase mainly after midnight. Due to the southerly winds and increased cloud cover, overnight lows will be mild - in the 30s and 40s. By Friday morning the shortwave and associated front will be moving across Tennessee. The forecast soundings show a dry lower levels with near saturation from about 8-10kft. Therefore, rainfall amounts during the late morning through the remainder of the afternoon will be rather light (less than one tenth). The exception would be areas south of I-40 such as McMinn, Marion, Hamilton and Bradley Counties where amounts could be closer to one quarter inch. .LONG TERM...(Friday night through Thursday)... Model agreement is a bit better than 24 hours ago, but still some significant differences in the details. Forecast confidence continues to be slightly above average for this time of year. A few patches of light rain may linger into the first part of Friday night, but while the deeper moisture clears out it appears a lack of low level drying may allow low clouds to linger into Saturday, especially south, before breaking up. High pressure to our north will slide east Saturday night and Sunday, and flow will turn more southerly allowing moisture to begin to increase. Clouds will be increasing from southwest to northeast later Saturday night and Sunday, but precip should hold off allowing Sunday to be dry. A mid/upper level trough will dig into the plains and then shift east into the Eastern US Sunday night through Tuesday night. The surface low will track by to our west and into the Great Lakes and then Eastern Canada, with a cold front pushing through our area most likely Monday night/early Tuesday. The best chances for rain will be Monday afternoon through Tuesday morning. This will be a warm system on the front end, so the bulk of the precipitation will be liquid. Colder air moving in behind this system may bring some snow showers on the back end Tue night, then Wednesday and Thursday look dry. One thing to watch will be the strength and wind direction in the low level jet Sunday night through Monday night, as mountain wave enhancement of the winds may occur. There may also be some heavy rainfall especially Monday night/early Tuesday ahead of the front. However, models have not been consistent and are not in good agreement at this point with any of these details, and confidence is still too low to include these in the HWO at this time. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 42 53 43 56 / 10 60 40 10 Knoxville McGhee Tyson Airport, TN 38 50 39 56 / 10 50 20 10 Oak Ridge, TN 38 49 39 56 / 10 60 20 10 Tri Cities Airport, TN 34 48 36 53 / 10 50 20 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ AC/LW

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