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

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369 FXUS64 KMRX 231931 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 331 PM EDT Sun Jul 23 2017 .SHORT TERM (Tonight and Monday)...
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Over the next few hours and into the evening, the showers and storms in our southern tier should be decreasing, while activity to our north near a pre-frontal trough should be increasing. The short term rapid refresh models point toward convective development near our border with KY in the 23Z-02Z time frame, which seems reasonable as mesoanalysis shows a stability gradient in that area. PoPs through the evening will be in the likely range in northern sections, then gradually decrease as the storms progress southward overnight. A threat of damaging wind gusts cannot be ruled out in northern sections. Tomorrow the surface convergence zone and 850 mb theta-e front will be to our south, leaving a NW flow through the low and midlevels, which should keep the convection mainly south. Southern sections may have a slight chance of showers, but forecast soundings from the NAM and GFS look quite stable and dry aloft tomorrow. There will be a cold front across the Ohio River that will be moving into KY, but moisture and instability ahead of it looks unfavorable for much development or any severe threat. .LONG TERM (Monday night through Sunday)... An upper trough will continue to move east of the area Monday night through Tuesday night. PW values will remain slightly above average for this time of year...and winds will shift to out of the NW. Monday night will see the best forcing in areas south of I40...but the best instability will be north of I40 where less of an inversion develops overnight. Have included only slight chance precip in the southern areas for any diurnal storms that develop through the afternoon...but otherwise Monday night should be fairly dry. Diurnal showers and thunderstorms are possible Tuesday afternoon...though PW values will continue to decrease as the NW flow impacts the moisture available. If any storms do develop...expect a few to become strong...but no severe storms expected. Wednesday...High pressure develops over the coastal states as a frontal boundary begins to move through the MS River Valley towards the area. Models have been inconsistent with drying out the atmosphere for no showers and thunderstorms expected. Would not be surprised to see an isolated shower form...but otherwise Wednesday and Wednesday night look dry. The frontal boundary then approaches the area Thursday...with scattered showers and thunderstorms developing ahead of the front. Most of the activity should remain over the Plateau and SW VA where the best lift will be located. Coverage of showers and thunderstorms increases for Friday as the front swings through the area. Low instabiltiy will be present with a very moist atmosphere. With the light winds...severe weather does not seem to be a threat...though heavy rainfall could cause concerns across the area. Saturday and Sunday...showers and thunderstorms are again possible as an upper level trough tries to swing through the area.
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Chattanooga Airport, TN 74 90 73 90 / 40 20 20 40 Knoxville McGhee Tyson Airport, TN 73 90 71 90 / 60 10 10 20 Oak Ridge, TN 73 91 71 90 / 60 10 10 20 Tri Cities Airport, TN 69 90 67 88 / 60 10 10 20
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ DGS/JW is the U.S. government's official web portal to all federal, state and local government web resources and services.