990 FXUS64 KMRX 251927 AFDMRX AREA FORECAST DISCUSSION National Weather Service Morristown TN 327 PM EDT Wed May 25 2022 .SHORT TERM...(Tonight and Thursday)... Key Messages: 1. Showers and some thunderstorms around at times. Some storms may be strong to severe Thursday. 2. Gusty winds in the mountains and foothills. Discussion: An upper low will drift east from the Plains into the mid Mississippi Valley during the period. Models show the 850mb jet generally around 30 to 35 kts from the south/southeast during much of the period and strong moisture transport brings PW values above the 90th percentile for this time of year with values over 1.5 inches across much of the area. The upper jet rotating up the east side of the closed low brings some upper forcing from the right entrance region during Thursday as well. A surface cold front will be moving across Middle TN by late Thursday. The current band of showers moving into our southwest counties will shift east, but expect thunder chances will continue to be limited. Downslope flow from the southeast low level jet moving across the mountains will also act to inhibit precipitation in the northern/central valley areas. Thursday is still showing mixed signals but overall the trend has been to show less CAPE and less impressive shear overall. There still does appear to be a risk of strong to severe storms especially south and west from the southern valley across and near the Plateau. Damaging winds will be the primary threat along with the low probability of a brief tornado, especially if there is enough destabilization before the better jet dynamics arrive. However, there is still considerable uncertainty at this time how all of . this will evolve. In addition, bands of showers/storms aligned with the flow may lead to training and a flooding threat, again with the highest threat southern and western portions of the area. Will keep this mention in the HWO. Finally, the low level jet strength direction looks favoroble for mountain wave enhancement of the winds, although the overall set up including the vertical thermal profile does not look great for strong winds. Right now it looks borderline so will keep wind gusts near 40 mph in the favored areas and not issue any wind advisory. The gusty winds will be mentioned in the HWO however. .LONG TERM...(Thursday Night through Wednesday)... Key Messages: 1. Showers and storms will linger early in the period with a few stronger storms possible Thursday night. Rain chances will then decrease substantially after Friday. 2. A gradual warmup is expected through the period with increasing likelihood of 90+ degree temperatures by mid-week. Thursday Night through Sunday At the start of the period, a closed low will be advancing from the Mississippi River Valley with an occluding surface low centered just to the north. Continued advancement of these features will keep lingering rain chances in the forecast with a focus on the regions ahead of the occluded front. Early in the night, 850mb flow will be nearly SE at 30-40 kts, keeping gusty winds in the mountains. With potential for lingering low-end instability and deep-layer shear of over 30 kts, a few strong to severe storms will remain possible. Low- level shear will be impressive in the first part of the night before the flow becomes more uni-directional. With strong low-level flow, this will keep a focus on potential for an isolated tornado, in addition to damaging winds. However by Friday, the overall shear becomes less impressive with low-end instability keeping the mention for thunder. This comes as the system begins to lift out of the area. By Saturday, the closed low will continue to lift northeastward, leading to gradually drier and warmer conditions. A few showers could linger in northeastern areas, but much of the area will remain dry as moisture and instability are both very limited. By Sunday, ridging will be in place, leading to sunnier and continually warmer temperatures, likely rising above normal as 500mb heights approach 5,850 meters. Monday through Wednesday By early next week, a significant ridge will be in place with a ~5,940 meter 500mb high suggested to be centered near Ohio by Tuesday. This also comes in conjunction with high pressure centered in our area at the surface. Since these heights are comparable to the normals in July, it is likely that temperatures will reach to near or above 90 degrees again across much of the lower elevations. By mid-week, the upper pattern will remain largely the same with indications of potential moisture return justifying PoPs. BW && .AVIATION... 18Z TAF DISCUSSION. Will see some showers and thunderstorms around at times during the period, but timing is still problematic. Best chance for thunder looks to be at CHA, with lesser chances further northeast. Will try to time higher probability times for thunderstorms with VCTS and prob30 groups at CHA/TYS. Will just have VCSH and prob30 for showers at TRI as thunder chances look too low to include for now. Expect MVFR level cigs at CHA for much of the period, but outside of a heavier shower/thunderstorm expect TYS and TRI to be mainly VFR. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 66 76 60 76 58 / 80 90 70 20 10 Knoxville McGhee Tyson Airport, TN 67 80 62 75 58 / 60 90 90 40 20 Oak Ridge, TN 66 79 60 75 57 / 70 90 80 50 20 Tri Cities Airport, TN 63 80 60 76 56 / 50 70 90 70 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$