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

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000 FXUS64 KMRX 250730 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 330 AM EDT Thu May 25 2017 .SHORT TERM (Today and Tonight)...
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An upper low will move across the eastern Ohio Valley Today. Associated short-wave will swing across eastern Kentucky into southwest Virginia and northeast Tennessee. Divergence along with this wave will produce an area of showers, mainly along and north of interstate 40. The tightening pressure gradient associated with this wave will produce a 850mb jet of 35-45kts. Breezy conditions are expected with gusts up to 35kts, especially across the higher elevations of southwest Virginia and northeast Tennessee. Wind speeds are close to advisory criteria. Plenty of rain/clouds will produce unseasonably cool conditions across southwest Virginia/northeast Tennessee today. For this evening, the upper trough axis will move east of the Appalachians ending the rain chances with sky cover clearing. Winds decouple, but remain breezy enough to help keep fog development limited. .Long Term (Friday through Wednesday)... A dry day on Friday as upper low lifts NE toward New England and broad ridge axis begins to build in across the area. A series of shortwaves begin moving across the ridge Friday night that will increase POPs, particularly over the northern half of the area by Saturday. With low level return flow beginning in earnest on Saturday, temperatures will climb back into the middle to upper 80s across much of the area as dewpoints climb back into the middle to upper 60`s by Sunday. With plenty of instability area wide Saturday, afternoon and evening showers/tstms will be possible. Greatest chances will be found over the northern half of the area where expected CAP is weakest. Ridge axis shifts east by Sunday in advance of deepening Great Lakes low. Continued strong instability and eroding CAP will bring likely tstm POPs back into the fcst. Approaching upper level jet by late Sunday could help in making some of those tstms strong to marginally severe mainly over the northern half of the area where the instability and jet dynamics are best combined. By Monday upper level flow is becoming parallel to the surface front, slowing it`s progression as it moves across the area and prolonging the period of chance POPs through the holiday. Beyond Monday, much of the area remains in slight chance POPs through Wednesday as broad troughing aloft persists with a few weak spokes of shortwave energy rotate across the area.
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Chattanooga Airport, TN 75 55 85 65 / 10 0 10 10 Knoxville McGhee Tyson Airport, TN 69 55 81 65 / 50 10 10 10 Oak Ridge, TN 70 55 84 65 / 50 10 10 20 Tri Cities Airport, TN 62 52 79 59 / 90 30 10 20
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