The cold's moving in
Cold weather is really going to start dominating the middle of the country over the next 24 hours and really does not look to relinquish its grip for the rest of the month. Temperatures for the 1-5 and 6-10 day forecast periods will likely be colder than what we see in the 11-15 day period, but even in the 11-15 day time frame you can't rule the pattern as anywhere close to being "warm."
It is a cold enough pattern where we are going to see some frost and freeze threats, which even for far northwestern parts of the Midwest would be unusually early if indeed they were to occur. 30s for lows tomorrow morning should be common for the eastern Dakotas, Iowa, Minnesota and Wisconsin. There will probably be isolated locations in the far northwestern Corn Belt that reach 32 degrees tomorrow morning but the vast majority of locations will easily stay above that level. On Wednesday morning we will see 30s for lows for far eastern Minnesota, far eastern Iowa, and points eastward and I think that Wisconsin in particular has the potential for lows to 32 or lower that morning.
Additional frost/freeze threats for the Corn Belt look likely for this coming Saturday and Sunday mornings as well, with the air mass at that time projected to be cooler than the one that we see over the next 48 hours. With regards to rainfall, clearly the biggest totals will be south of the Ohio River where there is going to be widespread rain from now through Wednesday morning in the Delta and Southeast. Biggest totals in that area will be on the order of two to four inches and locally heavier.
A couple chances for rain for this work-week in the Midwest will be producing just light totals there, and even less will fall in the Plains. Most of the Nation looks rather dry then for the 6-10 day time frame.
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