Prepare for Arctic air

Problem

High pressure sliding down from Canada will bring a surge of Arctic air into the northern Plains on Tuesday...which will spread south and east across the central U.S. on Wednesday. At the leading edge of the Arctic air...a cold front will trigger light snow showers while it crosses the
Great Lakes Tuesday night into Wednesday.

Weak impulses rippling through aloft will keep conditions unsettled from the Pacific Northwest to the northern and central Rockies early this week. The heaviest precipitation should focus along a wavy frontal boundary setting up over Oregon as well as along the favored slopes of the terrain.

Above normal temperatures across the northwestern corner of the Nation will keep any snow confined to the higher elevations of the Rockies and Washington Cascades.

An upper low lifting out of northern Mexico...combined with moisture returning from the Gulf of Mexico...will spread light to moderate rain across South Texas and along the Gulf Coast states.