...There is a slight risk of severe thunderstorms from the Northern High Plains to the Upper Mississippi Valley/Upper Great Lakes with an embedded region of moderate risk of severe thunderstorms over parts of Southern South Dakota...
...Heavy rain possible over the Great Lakes/Ohio Valley to Northern
A front extending from the Upper Great Lakes southwestward to the Central High Plains will move eastward to the Southern New England Coast by Wednesday afternoon and move southward to the Virginia Coast by Thursday.
A wave of low pressure will develop over the Central High Plains and move eastward to the Ohio Valley by Thursday.
Moisture will pool along the boundary aiding in the development of showers and thunderstorms over the Northern High Plains to parts of the Upper Great Lakes/Upper Mississippi Valley on Tuesday evening into Wednesday morning. The showers and thunderstorms, with heavy rain at times, will move eastward to the Lower Great Lakes/ Ohio Valley to the Northern Mid-Atlantic Wednesday afternoon into Thursday morning. Light to moderate rain will also develop over parts of the Northeast by Thursday morning.
An other front over the Northern Rockies will slowly move eastward to
Central Rockie/Great Basin by Thursday. The system will produce showers and thunderstorms over parts of the Northern Rockies/ Northern High Plains through Thursday.
In addition, onshore flow will produce light rain over parts of the Pacific Northwest also through Thursday.
Elsewhere, Low pressure over the Northeast will slowly move off the
Northeast Coast by Wednesday morning. The system will produce light rain over most of the Northeast waning to coastal Maine by Wednesday evening.