...Heavy rain possible over parts of the Central Plains...
...Temperatures will be 10 to 25 degrees below average for parts of the Northern High Plains...
A developing deep upper-level low over the Pacific Northwest will dig
southward to the Great Basin by Tuesday. In the meantime a front
extending from the Upper Great Lakes to the Central Plains then into the Northern Rockies will move off the Northeast and Mid-Atlantic Coast by Monday night. The boundary will produce light rain over parts of the Upper Great Lakes that will move into the Northeast/ Lower Great Lakes by Monday morning, with snow at the higher elevations of the interior Northeast. The snow will end overnight Monday.
The digging upper-level trough will produce light snow over parts of the Northern High Plains and expand into the Great Basin, post frontal, by Monday and into parts of the Higher elevations of eastern California into the Central Rockies by Tuesday morning. As the upper-level trough deepens, moisture from the Western Gulf of Mexico will move northward over the Southern/Central Plains.
A much weaker upper-level impulse moving from the Central Gulf Coast to off the Southeast Coast will trigger evening showers and thunderstorms, on Sunday evening, along with nighttime rain over parts of the Central Gulf Coast into the Tennessee Valley/Central Appalachians Monday into Monday evening.
The moisture will overrun the east-west front over the Plains/ Mississippi Valley producing showers and thunderstorms over parts of the Central/Southern Plains Monday night into Tuesday. Rain will develop north of the boundary on Tuesday from parts of the Central High Plains to the Middle Mississippi Valley.