21.   Pacific and modified polar air have jousted back and forth over the Plains this week.

22.   Polar air will return to the Northeast on brisk breezes from the west after a cold front moves offshore on Thursday morning.

23.   Polar air will flow back into the Northeast on Saturday as low pressure strengthens near Nova Scotia.

24.   Pleasantly cool, dry autumn air will occupy the Midwest and snow will develop over western Montana as polar air pours into the region.

25.   Polar air will surge into New England behind a strengthening cold front.

26.   Polar air will surge southward into the Middle Atlantic region and through the Ohio Valley.

27.   Snow showers will dust the western Great Lakes as polar air returns to the region on gusty winds.

28.   Strong winds from the north will drive polar air deep into the South.

29.   The boundary between polar air and a moderating air mass over the South will become established from Kansas to western New England.

30.   The boundary with polar air over Canada will be active from the Great Lakes to Montana.