From The Weather Channel - weather.com:
After a brief respite, another significant episode of severe weather is poised to strike parts of the Plains, Great Lakes and Ohio Valley.
It all begins Tuesday afternoon. Scattered thunderstorms are expected to fire up in the northern High Plains of central and eastern Montana, northeast Wyoming, and western South Dakota, with a threat of a few tornadoes, large hail, and damaging winds. To the east, a few severe thunderstorms with hail are possible in New England, including Boston.
Tuesday night, a complex of thunderstorms will roll east-southeastward through South Dakota, northern Nebraska into southern Minnesota and northern Iowa, with a threat of damaging winds and locally heavy rainfall.
Wednesday, severe thunderstorms will reignite along a strong warm front from eastern Iowa, northern Illinois and southern Wisconsin into Indiana, southern Lower Michigan and Ohio. This could affect the Wednesday afternoon/evening commute in Chicago, Milwaukee, Detroit and possibly Cleveland. Damaging winds, large hail, some tornadoes, and local flash flooding from brief heavy rainfall are all threats.
Wednesday night, a cluster of severe thunderstorms, possibly in the form of a squall line with damaging straight-line winds, will sweep through this region as far east as southwest New York, western Pennsylvania, and northern West Virginia. Cities in this late threat include Pittsburgh and Columbus, Ohio.
Thursday, the threat shifts to the East as the cold front and attendant upper-level dip in the jet stream sweep in. Damaging straight-line winds, large hail and a few tornadoes are possible in the Mid-Atlantic States, including Philadelphia, Baltimore, and Washington, D.C. Damaging straight-line winds and heavy rainfall are the main threats farther south Thursday from the southern Appalachians and Tennessee Valley to southern Virginia and the Carolinas.
Tornado/wind threat on Wednesday, June 12:
Scattered severe thunderstorms, possibly in clusters or even a derecho (widespread damaging wind event associated with a bow echo thunderstorm pattern) in northeast IA, south WI, north half IL, north IN, south MI, OH, southwest PA, north and central WV, MD, DC, north VA. 30% chance of a tornado within 50 miles of a location northern IL, southern MI, northern OH