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

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000 FXUS64 KMRX 220727 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 327 AM EDT FRI JUL 22 2016 .SHORT TERM (Today and Tonight)...
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A strong upper level ridge continues to be in control of the weather across most of the CONUS keeping conditions hot across the area. The center of this nearly 600 dm high is currently located across the Texas panhandle. Temperatures today will top out once again in the 90s with near 100 degrees across the Southern Valley. Heat indices will range just below advisory criteria with values in the 100-103 degree range possible for locations in the Southern Valley with mid to upper 90s further north. Current water vapor imagery and RAP upper air analysis indicates a weak shortwave trough moving across the Great Lakes into the OHio River Valley around the periphery of the upper level ridge. Models forecast that this trough will move through the Southern Appalachians later this afternoon. PW values will range from 1.5-1.7 inches, which is slightly above normal. Based on timing and location of the shortwave later this afternoon, it appears that SW NC will have the highest chances for a few scattered showers/storms. SBCAPE values will range from 1000-2000 J/Kg with 0-6 km bulk shear values of 15-20 kts. A storm may pulse up to become strong but do not expect any severe storms. Any ongoing isolated to scattered convection should come to an end shortly after sunset. Some of the models are trying to show continued activity during the overnight hours but the upper level and mid-level flow is mostly anti-cyclonic. With the lack of any lifting mechanism and PW values near to just slightly above normal, lowered PoPs during the overnight hours with most the activity today expected to be diurnally driven. .LONG TERM (Saturday through Thursday)... Early in the extended an upper ridge of high pressure will remain centered over the central U.S...placing the Southern Appalachian Region in northerly flow aloft. A series of weak disturbances riding along the upper flow will track into the area...providing weak lift and a chance of scattered convection through the weekend. The ridge weakens over the area early in the work week and flow aloft becomes more zonal allowing a weak boundary to sag into the region through the rest of the extended. This will bring an increase in low level moisture and a focus for convective development. The result will be a chance of showers and thunderstorms each period...though coverage will be scattered. As for and rather humid conditions will persist through the period...though 90s across the valley this weekend will lower slightly to mid 80s to low 90s by the middle of the week as the boundary slowly drop into the area.
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Chattanooga Airport, TN 98 75 96 76 / 20 10 30 20 Knoxville McGhee Tyson Airport, TN 95 73 94 72 / 10 20 40 20 Oak Ridge, TN 96 73 94 72 / 10 10 30 20 Tri Cities Airport, TN 93 69 92 70 / 10 20 40 30
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ MA/MJB is the U.S. government's official web portal to all federal, state and local government web resources and services.