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

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000 FXUS64 KMRX 261932 AAA AFDMRX Area Forecast Discussion...UPDATED National Weather Service Morristown TN 332 PM EDT Fri May 26 2017 .SHORT TERM /Tonight and Saturday/... High pressure ridge will still be in control overnight, promoting a mostly clear sky with some light winds across the region. The clear sky will allow for good radiational cooling after sunset, with temperatures quickly dropping into the 70s to upper 60s. Some higher dewpoints across the area, however, will help keep lows from dropping as low as the previous night -- only bottoming out into the upper 50s to mid 60s by early Saturday morning. The potential for an active severe weather day will exist on Saturday, though it will be dependent on a number of factors. Moist, Gulf air will continue to stream into the area from the southwest as the aforementioned upper-ridge over the Gulf scoots off to the southeast. This will allow a weak front to drift from the Ohio River closer to the Tennessee Valley into Southern Kentucky. Some of the latest guidance does suggest that convection overnight along the front may sent a outflow boundary(ies) into the region (perhaps along the I-40 corridor) by the late morning. This feature could serve as a focus for convection later on in the afternoon -- along with the front itself. Given the highly unstable airmass (with MLCAPEs at around 2500-3000 J/kg), this feature(s), may be enough to overcome the inhibition that is also progged to be in place. Should this occur, any storm that does develop will quickly become strong to severe, with large hail and damaging downburst winds possible (thanks to drier air near the surface). However, exact timing and the scope/coverage is uncertain at this time. The greatest threat will likely favor areas across southwest Virginia and other locations north of the I-40 corridor. Overall, do think there is a good chance for at least a few scattered severe storms during the afternoon and evening, but the chances may not be as high as those later on Saturday night and on Sunday. Still, those with outdoor plans on Saturday should closely monitor the weather. .LONG TERM /Saturday Night through Friday/... Any ongoing convection Saturday afternoon will linger into Saturday evening for a continued chance of thunderstorm activity. The air mass will remain unstable overnight with low level moisture increasing. Additional convection could move in towards morning with the remnants of a convective complex approaching the area. A cold front will push towards the area on Sunday with a line of organized showers and thunderstorms is expected to move across the area for the afternoon. Throughout the Saturday night and Sunday time frame...with the instability in place and an approaching 850MB jet...we could see a few storms become strong to severe. The main threat is expected to be strong...gusty thunderstorm winds and large hail. A second line of convection may form Sunday night into Monday for an additional round. A few showers may linger into Monday evening as the front exits the area. Should briefly be between systems for Tuesday. Wednesday...models trending towards bring in a weak/dissipating frontal boundary. Little moisture or energy associated with the feature and will only put in low POPs. Confidence becomes quite low by the end of the extended but should see the next system approach the area around the Thursday/Friday time frame for our next chance of convection && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 66 85 69 85 / 10 40 40 70 Knoxville McGhee Tyson Airport, TN 65 83 66 82 / 10 30 50 70 Oak Ridge, TN 65 82 66 82 / 10 40 50 70 Tri Cities Airport, TN 59 80 64 80 / 10 50 50 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ AMP/MJB

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