Jesse Risley
Staff member
Today looks to be what was initially more of a sleeper day for the mid-Mississippi valley. A seasonably potent low pressure system will be situated over NC MO by mid-afternoon as an associated mid-level jet streak moves over the mid-Mississippi valley. A warm front presently situated over SC IL in C MO will gyrate northward today, though models may be slightly overdoing the northward extent of its progression due to lingering snow cover from last Monday's blizzard that could impact overall baroclinicity of the lower troposphere (you can see the change in snow pack on vis sat loops even this morning). Fairly modest cooling aloft should help usher in steeper lapse rates as the boundary layer destabilizes through early afternoon, though models have been consistently showing ample 0-3 km MLCAPE through large parts of the warm sector where favorable low-level shear will be juxtapose itself with a narrow corridor of said instability.
CAMs have been honing in on several areas of interest. First, C and SC IL in EC MO will have the most favorable instability parameters if present forecast models come to fruition, where a pre-frontal trough looks to possibly trigger convection INVO of STL and points ENE this afternoon; surface winds have been slowly backing here this morning, particularly favoring a region from STL-SPI-PPQ and perhaps slightly east and NE of that area. This would be a primary, synoptically favorable region for supercells with these types of setups. However, the region closer to the triple point across NE MO, WC IL and extreme SE IA will also be on the northern fringe of the instability axis in a region with otherwise favorable low-level shear parameters more proximal to the actual surface frontal boundary, and CAMs have been indicating deeper convection in this region, consistently, for the last 36 hours of model runs. If storms can remain in a favorable environment and orient themselves favorable to the surface boundary, this area bears watching closely too, as does the entire warm sector. Historically speaking, these 0-3 km MLCAPE profiles when juxtaposed with favorable low-level shear and a late fall or early spring cyclone have consistently yielded low-top supercell tornadoes on what might initially appear to be a fairly marginal setup.
CAMs have been honing in on several areas of interest. First, C and SC IL in EC MO will have the most favorable instability parameters if present forecast models come to fruition, where a pre-frontal trough looks to possibly trigger convection INVO of STL and points ENE this afternoon; surface winds have been slowly backing here this morning, particularly favoring a region from STL-SPI-PPQ and perhaps slightly east and NE of that area. This would be a primary, synoptically favorable region for supercells with these types of setups. However, the region closer to the triple point across NE MO, WC IL and extreme SE IA will also be on the northern fringe of the instability axis in a region with otherwise favorable low-level shear parameters more proximal to the actual surface frontal boundary, and CAMs have been indicating deeper convection in this region, consistently, for the last 36 hours of model runs. If storms can remain in a favorable environment and orient themselves favorable to the surface boundary, this area bears watching closely too, as does the entire warm sector. Historically speaking, these 0-3 km MLCAPE profiles when juxtaposed with favorable low-level shear and a late fall or early spring cyclone have consistently yielded low-top supercell tornadoes on what might initially appear to be a fairly marginal setup.
