Mesoscale Discussion 0228 NWS Storm Prediction Center Norman OK 0234 PM CDT Tue Mar 24 2020 Areas affected...Parts of southwestern into middle Tennessee...northestern Mississippi and northwestern Alabama Concerning...Severe potential...Watch likely Valid 241934Z - 242130Z Probability of Watch Issuance...80 percent SUMMARY...The risk for severe thunderstorms is expected to increase during the next few hours. By 5-7 PM CDT, this probably will include potential for supercells capable of producing tornadoes, particularly near/northeast of Tupelo MS into areas near and northwest of Muscle Shoals AL, Huntsville AL and the Shelbyville, Tullahoma area of southern Middle Tennessee. DISCUSSION...As one weakening mid-level jet streak continues to propagate across the Mid South, toward the southern Appalachians, the exit region of another (70+ kt at 500 mb) is forecast to dig east-southeast of the Ark-La-Tex through central Mississippi by 23-00Z. As this occurs, weak to modest mid-level height falls appear likely to overspread a destabilizing boundary layer, along and south of a surface frontal zone now near/just north of Memphis TN, Muscle Shoals and Huntsville AL. Insolation and surface dew point increases through the lower/mid 60s appear to be contributing to mixed-layer CAPE in excess of 1000 J/kg, with remaining inhibition becoming increasingly negligible. In the presence of strong deep-layer shear, the environment is becoming conducive to organized severe thunderstorm development, including discrete supercells. While the front may become a focus for this convective development, model output suggests additional discrete storm development is possible along the low-level jet axis extending southward across at least much of northern Mississippi. As a weak frontal wave redevelops eastward from parts of northern Arkansas into northern middle Tennessee, the latest Rapid Refresh forecast soundings continue to suggest that low-level hodographs will become most conducive to tornadic supercells near/northeast of Tupelo MS, into the Muscle Shoals and Huntsville TN vicinities, and areas near/west of Tullahoma TN by 5-7 PM CDT. This will include potential for an isolated strong tornado or two. ..Kerr/Thompson.. 03/24/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OHX...BMX...HUN...MEG... LAT...LON 34598984 35378927 35798794 35588630 34708659 33798852 33918977 34598984