1PM Day 3 Convective Outlook for Friday, January 9. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER MS VALLEY INTO THE TN VALLEY
SUMMARY
Severe thunderstorms are possible on Friday from the lower Mississippi Valley into parts of the Mid-South and Southeast.
Lower MS Valley into parts of the Southeast and TN/OH Valleys
In the wake of a negative-tilt shortwave trough and related surface low departing the Great Lakes region, a front will extend from the surface low southwestward along the lower/middle OH Valley into the Arklatex through the first half of the period. During this time, broad low-level warm advection amid a relatively moist air mass ahead of the front will support training thunderstorms beneath a belt of strong, front-parallel midlevel southwesterly flow. Despite poor deep-layer lapse rates and limited buoyancy, around 50 kt of effective shear may promote a couple strong to severe storms capable of damaging winds, isolated severe hail, and possibly a brief tornado into the afternoon hours.
In the 21-03Z time frame, midlevel height falls accompanying a broad upstream trough will impinge on the frontal zone over the Mid-South vicinity. In response, a frontal wave will evolve into a surface low while tracking east-northeastward across the TN Valley during the overnight hours. Strengthening low-level warm-advection amid a plume of moist/uncapped air (middle/upper 60s dewpoints) will yield a quick uptick in thunderstorm coverage across the lower MS and TN Valleys. Around 50-60 kt of effective shear and enlarging low-level hodographs ahead of the low will conditionally favor a mix of organized clusters and semi-discrete supercell structures -- posing a risk of damaging winds and possibly a couple tornadoes. However, weak buoyancy and the potential for many storm interactions increase the overall conditionality of the tornado risk.