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

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299 FXUS64 KMRX 190740 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 340 AM EDT Thu Apr 19 2018 .SHORT TERM...
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(Today and Tonight)... The frontal boundary will be east of the area by sunrise...with northerly flow prevailing through the day on Thursday. Cooler and drier air will keep temperatures several degrees below normal Thursday and Thursday night...with a Frost Advisory and/or Freeze Watch needed for most of the area. Clouds will be slow to clear through the day...with only far NE TN and SW VA having lingering clouds by late Thursday afternoon. .LONG TERM...(Friday through Wednesday)... Upper level ridging builds in from the west on Friday and Saturday. Fire weather concerns will be possible on Friday afternoon with minimum RH values around 25-35 percent. Increasing heights aloft and insolation will push temperatures up into the 60s. Another cold start will be possible on Saturday morning with patchy frost possible across SW VA and NE TN. A frost advisory may become necessary for these areas on Saturday morning. The ridge axis will be over the area on Saturday with a closed low across the Great Plains. With plenty of sunshine, increased highs by a few degrees on Saturday in the upper 60s and low 70s. Minimum RH values will be a little higher with some weak moisture advection Saturday afternoon with RH values in the 35-45 percent range. Overall, Saturday should be a pleasant day for any outdoor activities. The evolution of the upper low to the east has been slower and slower with the latest model guidance. Last night the GFS indicated widespread rainfall across the area by the end of the day Sunday. The latest 00z GFS has slowed this down until Sunday night and the ECMWF is slower by about 12 hours. Therefore, have decrease PoPs on Sunday. Overall, think it will be dry for most of the area with increasing clouds. There could be some showers that move in across the Southern Valley and Plateau late in the day. Both the GFS and ECMWF indicate that the closed low will track across the Lower Mississippi River Valley into the Southeastern U.S early next week passing to the south. Due to this, do not anticipate any thunder and have only included showers in the forecast. With the latest timing, precipitation should be widespread across the Southern Appalachians by Monday. The highest precip. totals at this time look to occur to the south of the forecast area but depending on the track of the system, there could be the potential for some flooding concerns early next week.
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&& .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 59 40 67 43 / 0 0 0 0 Knoxville McGhee Tyson Airport, TN 53 36 64 40 / 0 0 0 0 Oak Ridge, TN 55 36 65 40 / 0 0 0 0 Tri Cities Airport, TN 52 32 60 34 / 10 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...Freeze Watch from late tonight through Friday morning for Cherokee-Clay. TN...Freeze Watch from late tonight through Friday morning for Blount Smoky Mountains-Cocke Smoky Mountains-East Polk-Hancock- Hawkins-Johnson-Northwest Carter-Northwest Greene-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Southeast Monroe-Sullivan-Unicoi-Washington TN. Frost Advisory from 1 AM EDT /midnight CDT/ to 9 AM EDT /8 AM CDT/ Friday for Anderson-Bledsoe-Campbell-Claiborne- Grainger-Hamblen-Jefferson-Knox-Loudon-McMinn-Meigs-Morgan- NW Blount-North Sevier-Northwest Cocke-Northwest Monroe- Rhea-Roane-Scott TN-Union. VA...Freeze Watch from late tonight through Friday morning for Lee- Russell-Scott-Washington-Wise.
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&& $$ JW/MA

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