Hail in Knox County, Ohio

Hail up to half dollar-size along Treaty Road, about one-mile NNW of North Liberty.

During the early afternoon through early evening of May 1st, a surface low drifted northeastward from the southern Lake Michigan region to northeastern Lower Michigan. Simultaneously, the attendant warm front drifted north-northeastward across central and eastern Lake Erie, and northwest Pennsylvania toward Lake Ontario, while the low's trailing cold front moved generally eastward from northeastern Illinois toward western Lake Erie and northwest Ohio. Within the warm and moist sector and well-ahead of the cold front, a line of multicell thunderstorms propagated generally eastward across northern Ohio and generated periodic straight-line convective wind damage. Ahead of the line of storms, scattered multicells and isolated supercells moved northeastward and produced severe hail and periodic straight-line convective wind damage in northeast Ohio. These storms traversed an ambient environment that included weak to moderate MUCAPE and moderate to strong effective bulk shear.

The above-mentioned surface low had moved east-northeastward to southwestern Quebec by late morning of May 2nd. This low moved farther northeastward to central Quebec by the early evening. Accordingly, the low's warm front moved farther northeastward across portions of New England as the trailing cold front drifted eastward from western Lake Erie and near the Indiana/Ohio border toward central Lake Erie and the central-third of Ohio. Along the cold front, a second surface low drifted northeastward near the Lower Ohio Valley. Along and especially ahead of the cold front, scattered organized thunderstorms, including supercells, produced sporadic severe hail and straight-line convective wind damage as the storms moved generally eastward across northern Ohio. These storms traversed an ambient environment that included weak to moderate MUCAPE and moderate to strong effective bulk shear.

By the early evening of May 4th, the first surface low had moved northeastward from central Quebec to Atlantic waters just south of Greenland. This low moved little through the late evening of the 4th. Accordingly, the cold front had moved eastward to near the Atlantic coast from Nova Scotia to Georgia. By the early evening of the 4th, the second above-mentioned low had drifted northeastward from near the Lower Ohio Valley to the Mid Ohio Valley and became occluded. The occluded low meandered near the Mid Ohio Valley through the late evening as the occluded front moved northward from the Upper Ohio Valley toward Lake Erie. A northward-moving cluster of multicell thunderstorms associated with the occluded front generated straight-line convective wind damage in the Lake Buckhorn community, near Millersburg, during the early evening. These storms traversed an ambient environment that included weak MUCAPE and moderate effective bulk shear.

By the early afternoon of May 5th, the occluded surface low had retrograded (i.e. drifted generally westward) to the Lower Ohio Valley and moved little through mid-evening. Simultaneously, the attendant occluded front arced generally northeastward from the low and drifted northward in vicinity of the southern shore of Lake Erie. Low-level convergence zones associated with the occluded surface low's cyclonic circulation triggered scattered multicells and supercells in northern Ohio during the afternoon through mid-evening. These storms exhibited unusual forward motion toward the west, northwest, or north due, in part to the cyclonic circulation of the aforementioned occluded low that was vertically-stacked at the surface and aloft. These storms traversed an ambient environment that included weak to moderate MUCAPE and moderate to strong effective bulk shear.