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

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000 FXUS64 KMRX 220751 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 351 AM EDT Sat Apr 22 2017 .SHORT TERM (Today through Sunday)...
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For early this morning, areas of convection is moving northeast across the Tennessee valley due a series of waves moving along a frontal boundary over the area. The HRRR model shows these area of convection slowly weakening this morning and mainly staying over the northern half of the area. Active weather next 48 hours with a series of jet streaks enhancing the divergence aloft over the area. A frontal boundary across the Tennessee valley will be strengthen by the circulation around these jets. Fronto-genetic forcing along with increasing moisture/instability this afternoon will produce widespread showers and thunderstorms. MLCAPES of 1500 J/kg and PWs around 1.4 inches (which is near the daily max) will produce very heavy rains with the storms. Enough hail CAPE and mid-level dry air/850mb jet of 35kts to produce hail up to quarter size and potential of damaging winds with the stronger storms. For tonight, approaching and deepening upper trough over the mid- section of the nation will once again enhance the divergence aloft over the Tennessee Valley. Even though the frontal boundary will move south of the area, the pressure falls associated with the jet dynamics will produce an inverted surface trough across the southern Appalachians late Saturday night and Sunday. This boundary will focus around round of showers with heavy rains. Due to the persistent heavy rains, training of cells along these boundaries and climatology very high PWs, there is a potential of flash flooding. Have issued a Flash Flood Watch for flash flooding for the entire area from mid-afternoon through Sunday afternoon. Later shifts will need to especially watch the burn scar area in Sevier county. Warm today, but plenty of clouds and rain showers Sunday will keep temperatures cooler. .LONG TERM (Sunday Night through Friday)... Low pressure system will be slowly moving south and east of us as we head into the last portion of the weekend. We could see some wrap around showers Sunday night into Monday, with the best chances being along the Southern Appalachian Mountains. As the low continues to move to the east a ridge will start to build in from the west. This ridge will dry us out and help along a warming trend that will continue through the work week. Another frontal system will make a run at our area in the second half of the work week, but recent model runs suggest that this may fizzle out before it can bring any widespread precipitation to our area. By the end of the work week, models suggest that temperatures across the area will be in the 80`s with some locations possibly flirting with 90 degrees.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 81 57 64 52 / 70 90 80 30 Knoxville McGhee Tyson Airport, TN 77 56 60 50 / 80 90 90 40 Oak Ridge, TN 75 56 61 51 / 90 90 80 40 Tri Cities Airport, TN 74 53 58 48 / 90 90 100 60
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&& .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...Flash Flood Watch from 2 PM EDT this afternoon through Sunday afternoon for Cherokee-Clay. TN...Flash Flood Watch from 2 PM EDT /1 PM CDT/ this afternoon through Sunday afternoon for Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell-Claiborne-Cocke Smoky Mountains- East Polk-Grainger-Hamblen-Hamilton-Hancock-Hawkins- Jefferson-Johnson-Knox-Loudon-Marion-McMinn-Meigs-Morgan-NW Blount-North Sevier-Northwest Carter-Northwest Cocke- Northwest Greene-Northwest Monroe-Rhea-Roane-Scott TN- Sequatchie-Sevier Smoky Mountains-Southeast Carter- Southeast Greene-Southeast Monroe-Sullivan-Unicoi-Union- Washington TN-West Polk. VA...Flash Flood Watch from 2 PM EDT this afternoon through Sunday afternoon for Lee-Russell-Scott-Washington-Wise.
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