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

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000 FXUS64 KMRX 231930 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 330 PM EDT Mon Apr 23 2018 .SHORT TERM...(Tonight and Tuesday)... The closed low and associated surface low over NW TN will continue to slowly track eastward with rotating vort maxima around the center. A current vort max over NE AL will continue to initiate banded convection this evening with mostly unidirectional flow through the cloud layer. This could produce some heavier rain across the southern valley and southern plateau. Winds are expected to remain strong at 850mb with the NAM and RAP showing 50 to 60 kt magnitudes. Will continue the Wind Advisory and High Wind Warning areas, as is. With a moist boundary layer, bkn to ovc clouds, and breezy conditions through most of the night, expect temperatures to remain mild overnight slightly above normal. Scattered showers appear likely again Tuesday, especially in the afternoon. The upper-level low is expected to be over our forecast area by the afternoon resulting in rather steep mid-level lapse rates. Steeper lapse rates will help boost MUCAPE near 500 to 700 J/kg in the afternoon which will support some organized convection. Along with additional vort maxima providing support for ascent and lift, should see likely convection in the afternoon. Since the freezing level is expected to be between 7k- 8k ft, small sub-severe hail will be possible with some of the thunderstorms that develop. Winds shift to a more westerly direction during the day which may also enhance lift along the higher elevations with additional clouds and precipitation chances in the afternoon. Temperatures are difficult in this type of setup, but will trend near MAV MOS for max temperatures. .LONG TERM...(Tuesday night through Sunday)... The upper level low will slide to the east Tuesday night and into Wednesday with the surface low across the Mid-Atlantic. Some light wrap around precipitation will continue across the area with the best chances across the higher terrain along the TN/NC line and in SW VA. Wednesday night into Thursday morning should be dry as the system to the northeast continues to lift out. At the same time, another closed low will move out of the Central Plains into the Lower Mississippi River Valley on Thursday. The consensus of the models suggest this low will pass to the south of the area across MS/AL/GA keeping the majority of the forecast area dry. The latest NAM suggests that the low will move directly over the area bringing in widespread showers on Thursday. For now, have lowered PoPs for Thursday with highest PoPs across SE TN and SW NC. The upper level will eventually turn a bit to the north across the Carolinas keeping PoPs for the higher elevations along the TN/NC line into Thursday night. The pattern will remain progressive throughout the end of the week as yet another fast moving shortwave trough moves through the area on Friday. There will be a northern stream trough across the Great Lakes with a southern stream trough across the Lower Mississippi RIver Valley. With low level flow ahead of this system from the west to northwest, not expect much in the way of moisture and have reduced PoPs down into the slight chance category for Friday into Friday night. Upper level ridging will build into the forecast area over the weekend and into early next week with drier conditions and moderating temperatures. One thing to note is that late April and early May tend to be an active time of the year for strong to severe storms. Based on the latest long-term forecast, do not even have a mention of thunderstorms in the forecast after Tuesday. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 55 69 55 69 / 70 50 20 20 Knoxville McGhee Tyson Airport, TN 54 66 53 67 / 70 70 40 40 Oak Ridge, TN 54 67 53 67 / 70 70 30 30 Tri Cities Airport, TN 51 67 51 65 / 40 60 50 50 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...Wind Advisory until 2 AM EDT Tuesday for Jefferson-NW Blount- North Sevier-Northwest Carter-Northwest Cocke-Northwest Greene-Northwest Monroe-Sullivan-Washington TN. High Wind Warning until 2 AM EDT Tuesday for Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Southeast Monroe-Unicoi. VA...Wind Advisory until 2 AM EDT Tuesday for Russell-Washington. && $$ JB/MA

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