The Midwest has finally seen an end to the almost daily parade of clipper systems that moved through, each with a batch of snow. The upper level flow has become more west to east cutting off the source of the weather disturbances that had been dropping southeast out of Canada. Chicago experienced its greatest amount of snow all winter, all the way up to 9.2 inches for the season. Normal is 21.6 at this time so we are still way below normal.
The next several days will see a variety of weather over the Chicago metro area as several weather systems come in from the Pacific. The first is a system that will pull in some Gulf moisture as low pressure forms over central Illinois during Thursday in conjunction with a developing upper level trough. The graphic shows the expected Thursday evening storm position. Precipitation will start northwest sections late tonight and then spread southeast during the day. The question becomes what exact form this precipitation will be. It will greatly vary depending on location and time of day as the metro area will sit on the dividing line between rain and snow.
From the highs in the mid 30s today, lows will only drop into the mid to upper 20s tonight. Precipitation will start as freezing rain toward morning northwest parts of the metro area. During the day the precipitation will become rain from the city southward Thursday morning as temperatures warm into the mid to upper 30s. The far north sections will see freezing rain and rain turn to snow near the Wisconsin border midday. This snow line will then sag slowly southeast during the day. By evening areas near and northwest of an Aurora to Evanston line should have changed over to snow. This means several inches of wet snow (2-5" depending on location) will have fallen during the afternoon through the northwest portions of the metro area. Much heavier snow will fall across southern Wisconsin. The city and south will not change to rain until early Thursday evening. By this time the bulk of the precipitation will be ending so only minor accumulation expected in the bulk of the city, the far north side may see a little more.
Most of the snow will melt during the weekend as highs jump into the 40s Sunday ahead of a major Plains storm. Highs then stay in the 30s the rest of next week as milder Pacific air covers the Midwest. Our storm tomorrow will turn into a major Nor'easter Saturday with blizzard conditions and snow total of 18+ inches for parts of New England.
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