EF2 tornado in Geauga County, Ohio

An EF2 tornado with estimated peak winds of 115 mph impacted Middlefield. The tornado began just west of the intersection of OH Route 608 and Burton-Windsor Road where it caused minor damage to trees. This tornado then tracked southeastward and intensified before it completely destroyed a barn at a property along OH Route 608. The entire barn was lofted and displaced about 150 yards to the southeast, and the entire outer structure composed of cinder blocks collapsed. Extensive damage occurred to several other barns and trees at the same property. The tornado then travelled south-southeastward and damaged additional trees before dissipating just north-northeast of the intersection of OH Route 608 and Nauvoo Road.

At the surface, a low drifted east-southeastward across southern MN during the early afternoon of August 23rd through the predawn hours of August 24th. Simultaneously, a nearly-stationary front extended generally eastward from the low to central Lower MI and then south-southeastward through southeastern Lower MI to western OH. This front marked the eastern edge of an unusually-hot and very humid air mass concentrated over and near the central Great Plains and Lower OH Valley.

Aloft, a westerly low-level jet (LLJ) at and near 850 mb underwent very moist isentropic ascent aloft along the upper-reaches of the front. The LLJ triggered thunderstorm systems known as mesoscale convective systems (MCS's) over and near Lake Erie. These MCS's occurred amidst steepening mid-level lapse rates near 7C-8C/km, a tight westerly gradient in MUCAPE with weak to strong MUCAPE over Lake Erie and northern OH, and moderate to strong effective bulk shear. Simultaneously, the MCS's propagated generally westward (i.e. into the LLJ) as individual thunderstorm cells moved generally southeastward or southward. The MCS's evolved from elevated to surface-based as they propagated into a warmer and more humid low-level air mass over northern OH and the effective inflow layer transitioned from elevated over Lake Erie to surface-based farther south. These MCS's produced severe hail up to golf ball-size and straight-line convective wind damage.

During the predawn hours of the 24th through wee hours of the 25th, the surface low drifted east-southeastward from southern MN to near the border of southeastern Lower MI and northwestern OH. Simultaneously, the warm front preceding the low shifted northward and eastward as a warm front, and reached southern ON and Lake Ontario. The cold front trailing the low moved south-southeastward from the northern Great Plains to northern IN and IL, and southern IA and NE.

As the warm front advanced northeastward, convergence and moist ascent along the surface front triggered a cluster of thunderstorms amidst moderate MUCAPE, relatively-steep mid-level lapse rates near 7C/km, and moderate effective bulk shear. The cluster of storms persisted south-southeastward across Lake Erie and northern OH, and generated isolated straight-line convective wind damage in Cuyahoga County. During the late evening of the 24th through wee hours of the 25th, another MCS associated with the aforementioned cold front persisted generally eastward and southeastward across Lake Erie and northern OH. This MCS produced twelve mesovortex-related tornadoes and straight-line convective wind damage in northern OH as the MCS encountered moderate to strong effective bulk shear and MUCAPE, respectively, and steep mid-level lapse rates near 7C-8C/km. Mixed layer LCL's near 1000 meters AGL and surface-based ESRH near 200 meters squared per second squared contributed to a favorable environment for tornadoes.

Behind the MCS, a smaller cluster of multicell thunderstorms persisted southeastward across portions of northern OH during the predawn hours of the 25th. These storms generated localized straight-line convective wind damage in Morrow County. The storms encountered moderate to strong effective bulk shear, strong MUCAPE, and steep mid-level lapse rates near 7C/km, and apparently developed along the trailing outflow boundary of the preceding MCS.