Freezing and sub-freezing temperatures have occurred across the Northern Plains, Minnesota, Iowa, and Wisconsin, but killing freezes so far have been restricted to the northern tier of states.
|Lowest minimum temperatures since August 1.|
The first freeze across the central U.S. is running later than normal, but that could change this weekend.
A strong upper level trough will deepen over the eastern U.S. at the end of this week and the resulting northwesterly flow on the west side of the trough will bring frigid air deep into the central U.S.
|500 millibar map forecast for 7:00 a.m. CDT Saturday, November 1|
A strong surface high pressure system will drop out of Canada and by Saturday morning will be centered over the upper Great Lakes. Under clear skies and calm air temperatures will drop into the low 20s and perhaps lower over the upper Midwest, mid 20s over the central Midwest and below freezing as far south as the Ohio River. The Northern and Central Plains will remain on the periphery of the coldest air.
|Minimum temperature forecast for Saturday morning, November 1.|
|500 millibar map forecast for Tuesday, November 4 at 12:00 CST|
|Maximum temperature anomaly for Tuesday, November 4.|