Damaging wind, large hail, and a couple of tornadoes possible today!
Severe storms are most probable this afternoon and evening across parts of the mid-Mississippi Valley, with damaging wind, large hail, and a couple of tornadoes possible.
More isolated severe storms will be possible over portions of the southern and central High Plains, with large hail and damaging wind as the main hazards.
Are you prepared?
Now will be a good time to check your weather radios and have several ways to receive watches & warnings
A couple of overnight MCSs across KS/MO/IA have effectively merged into one large cluster now over northeast KS and northern MO. Outflow with the MO convection has sagged southward to the I-70 corridor, and could continue slowly southward through the morning given the large mass of rain and ongoing thunderstorms.
Meanwhile, a well-developed MCV over northeast KS will move eastward or east-northeastward today over northern MO, with the southern fringe of the MCV coinciding roughly with the west-east outflow near and just south of I-70.
A feed of low-mid 70s boundary-layer dewpoints will be maintained today across MO to the south and east of the ongoing convection, and moisture will also spread into IL during the day. The moistening will occur beneath the northeastern extent of a steep midlevel lapse rate plume from the southern Plains.
The net result will be a corridor of strong buoyancy (MLCAPE of 2500-3500 J/kg) along and south of the MO outflow boundary to roughly the Saint Louis area. Additional thunderstorm development is expected by afternoon along the outflow boundary, and perhaps a little to its south in the warm sector in MO.
Some enhancement of low-midlevel shear along the southeast flank of the MCV will contribute to an environment supporting supercells, within what is expected to become another larger storm cluster moving from MO into IL this afternoon.
Damaging winds will be the main severe threat (along with isolated large hail), though there will be enough increase in low-level moisture and shear near the outflow boundary/MCV to support the threat for a couple of tornadoes. The convection will likely weaken this evening once it moves east of the primary moisture/buoyancy corridor.
Simulated Refelctiviy for this evening around 3/4 PM CST through 7/8 PM CST
…Southern High Plains this afternoon/evening…
An outflow-assisted cold front has moved south to the TX South Plains and eastern NM, in the wake of overnight convection. Low-level flow will become more easterly/upslope through the day from northeast NM into southeast CO, which will again support thunderstorm development this afternoon on the Front Range. The initial storms could be supercells capable of producing large hail, given MLCAPE in excess of 2000 J/kg with steep midlevel lapse rates and effective bulk shear of 30-40 kt. Convection will likely grow upscale into a cluster or two capable of producing damaging winds this evening while moving east-southeastward toward the TX Panhandle, where the severe threat may persist through about 06z.
…Southeast WI to Northern Lower MI today…
Some cirrus blow off from the large MO storm complex may persist enough to slow surface heating some today along the synoptic front from southeast WI into northern Lower MI. Assuming a few cloud breaks can occur by afternoon, there will be a corridor of weak-moderate buoyancy along the front, which will help focus thunderstorm development. Isolated strong/damaging outflow gusts appear to be the main threat with these storms for a few hours this afternoon/evening.
…Southern AL to southeast LA this afternoon…
A weak midlevel trough will over the north central Gulf coast, along with daytime heating and local sea breeze circulations, will support scattered thunderstorm development by this afternoon. Very isolated strong downburst winds may occur with the strongest storms, but the overall severe threat appears too low to warrant adding wind probabilities…
SPC/Storm Prediction Center: Thompson/Dial.. 07/15/2020