KNOXVILLE, Tenn. (WVLT) -The mid and high level clouds that moved into the region early in the afternoon will be departing this evening. As skies clear out, temperatures will drop through the 70s, with most of the viewing area descending through the 60s after midnight. Low level moisture has been steadily increasing across the Tennessee Valley over the past twelve hours, and there is enough moisture now near the surface for the possibility of some fog formation, as that water vapor condenses in the cool late night air, with little wind flow to slow down the condensation process. By daybreak Monday, low temperatures will range from the upper 50s on some of the higher terrain, to the lower 60s across much of the Tennessee Valley. This cooling should be sufficient for patchy fog; especially near the waterways.
MONDAY: Skies will be only partly sunny, and thunderstorms will be building into the region from the mid Mississippi Valley during the day. Most of the higher resolution, mesoscale numerical models indicate that the best chance for these storms to be in the area will be during the afternoon. However, two of the models that we use regularly bring some of this convection into the WVLT viewing area during the morning, with continued progression across the region during the afternoon. It could end up being an active day for southern parts of the area, as the National Weather Service Storm Prediction Center has highlighted areas south of interstate 40 for the best possibility of seeing the stronger storms. At this time, it appears that the main threat with these storms will be straight line wind damage and possibly large hail. Most of this rain should be ending during the early to mid evening hours, as surface temperatures cool and the atmospheric lifting mechanisms move east of the Appalachians. Highs will reach the upper 70s and lower 80s on Monday. Winds will be westerly at 5 to 10 mph.
TUESDAY: A low pressure system will be moving east from the Missouri River Valley into the Ohio Valley, on Tuesday. There may be a few showers around during the morning, as the warm front associated with this pressure system advances north across east Tennessee and southeast Kentucky. There may be a break in the action through the middle part of the day, with periods of sunshine around noon into the mid afternoon hours. However, the Storm Prediction Center has outlooked east Tennessee and southeast Kentucky once again for the possibility of severe thunderstorms, as a squall line shifts east across middle Tennessee during the afternoon and into the WVLT viewing area during the evening hours; more specifically, from around 6 pm through midnight EDT. Once again, the main threat for much of east Tennessee will be due to damaging straight line convective winds and large hail. However, just to our west across middle Tennessee, the atmosphere will be configured for the development of stronger, supercell thunderstorms. This is due to expected moderate levels of instability, as well as a stronger wind field across middle Tennessee that will aid the generation of rotating updrafts. These are the types of thunderstorms that spawn tornadoes. Because the Cumberland Plateau is just east of this higher risk area covering middle Tennessee, there is a small possibility for tornado formation on this higher terrain in both Kentucky and Tennessee, on Tuesday evening. Due to that break in the overcast, with a period of mid day sunshine, our high temperatures will be just a little warmer, topping out in the lower and middle 80s. Winds will be southwesterly at around 10 to 20 mph with gusts to around 25 mph…