What a Difference a Day Makes!

A massive ridge of high pressure stretches all the way from central Canada southward across the Dakota's to Texas.  A strong low pressure storm center is located just to the south of James Bay. The pressure gradient between the high and low is what we call "tight" in the weather business. That means that there is a significant change in pressure over a relatively short distance across the earth's surface. It is shown on a weather map with the isobars (lines of equal pressure being drawn fairly close to each other. When a weather map looks like this, it is always an indication of plenty of wind, and we have had lots of wind for the last 24 hours pumping very cold Canadian air into the mid west. Northwesterly winds have been running 20 to 30 mph with higher gusts since last night following frontal passage. As the low pulls away tonight, and the high gets closer, the gradient will relax, and the wind will subside. The high temperature today occurred at midnight, and temperatures fell into the upper 20's this afternoon as the arctic air poured into the mid west. It certainly felt like the middle of winter this afternoon with wind chills in the middle teens. There were some snow flurries in the area today, too. Skies will clear tonight, and the temperature will drop off into the upper teens. The wind will subside to down to 10 to 15 mph from the northwest. On Saturday sunny skies will give way to partly cloudy conditions during the afternoon. It will be cold with a high in the low to middle 30's.  The average high this time of year is 43 degrees.  Another weather system moving across the northern plains along the Canadian border will pull some slightly warmer air into the Stateline on Sunday under partly sunny skies pushing the temperature up into the low 40's.  A cold front following the system will drop temperatures back into the 30's again on Monday.  A storm system is expected to develop over the southern plains.  It's anticipated track appears to be too far south to produce any measureable snow across northern Illinois... but it still needs to be watched on Monday night into early Tuesday.