Tuesday, October 28, 2014

Big but Short-Lived Chill on the Way

Temperatures have been mild for much of October throughout the U.S., with near normal temperatures across the central U.S. and Southeast. The mild weather along with extended periods of dry weather have made for nearly ideal harvest conditions.

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.
Recovery from the cold air will be quick. By next Monday the amplified upper level pattern will be flattening out and relatively mild Pacific air will be streaming across the U.S.

500 millibar map forecast for Tuesday, November 4 at 12:00 CST
That means the first week of November is likely to be warmer than average throughout much of the country east of the Rockies.

Maximum temperature anomaly for Tuesday, November 4.
The outlook from the Climate Prediction Center is for a higher probability of warmer than normal temperatures through the first half of November for most of the U.S.  However, accompanying the mild weather is a likely wet pattern in the Pacific Northwest and in the eastern half of the country.

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