Strong thunderstorms are expected to develop in eastern Iowa and northeastern Missouri this evening, and then move east into Illinois. Severe storms may occur, and the National Storm Prediction Center has issued the Mesoscale Discussion for this storm potential below:
Mesoscale Discussion 0585 NWS Storm Prediction Center Norman OK 0519 PM CDT Thu May 14 2020 Areas affected...Southeast Iowa and northern Illinois Concerning...Severe potential...Watch possible Valid 142219Z - 150015Z Probability of Watch Issuance...60 percent SUMMARY...Convective initiation is likely through 7 PM CDT across southeast IA and into northern IL. Hail and strong winds will be the primary threats with these storms. A watch is possible. DISCUSSION...Recent GOES visible imagery shows a cluster of developing storms across portions of far southeast IA within a broad low-level warm frontal zone. Continued thunderstorm development is likely within the next hour from this cluster with additional convective initiation possible further east into northern/northwest IL. Zonal deep layer flow along the warm frontal zone will favor discrete storms gradually growing upscale as they develop in an environment characterized by 1000-2000 J/kg MLCAPE and 30-40 knots of effective bulk shear. Sufficient CAPE/shear and a well-mixed boundary layer below 1 km suggest hail and strong winds will be the primary threats from these storms, while generally weak low level winds sampled from the KDVN VWP suggest a low tornado threat. A watch is possible if trends continue to favor a sufficiently widespread convective threat into northern IL.