The Midwest and the Chicago metro area are going to see some large weather swings into early next week. The arctic airmass over the Midwest today will be replaced by a mild flow of Gulf air by Tuesday. The high temperature swing will be from 30-40 degrees. The cold northwest flow pattern of the next couple of days will be replaced by a southwest flow with deep low pressure over the Plains by Tuesday.
In the short term another push of arctic air has moved over the Midwest. This time the low level wind flow is NNE which means a heavy lake effect snow band has come down lake Michigan. The graphic shows the radar picture from NWS LOT (Chicago) radar this morning. At the time local whiteout conditions over northwest Indiana were reported in the band. Local snow amounts of 6+ inches have been reported. With time the band will drift west and affect the lake shore areas over Illinois (including parts of Chicago) with a couple of inches of snow possible near the lake.
The lake snow setup will gradually break down later today as the winds become more southeast by evening and then southwest late tonight. The southwest flow ahead of a disjointed upper level trough approaching the area. As the trough moves overhead Friday morning, a general 1-2 inches of fluffy snow will fall over the metro area. Really hard to believe this will be the first widespread snow of 1+ inches for the metro area. Through yesterday January 23, Chicago has now gone officially 334 consecutive days without at least a one inch snowfall, a new record.
Over the next several days temperatures will take a wild ride down and then up. After a jump to 23 yesterday after the Tuesday morning low of -1 (the first Chicago subzero since February 2011), the new push of arctic air will hold highs in the upper teens today. Tomorow will rebound into the mid to upper 20s, the lower 20s Saturday and near freezing Sunday. By Monday we are in the mid 40s and Tuesday the low to mid 50s. Yes 50s, not a typo.
The high for Sunday will be extremely critical as a big slug of moisture comes up on a southwest flow at all levels. At this far distance it looks like snow will begin sometime Sunday afternoon before changing to sleet and then freezing rain in the evening before just rain late at night. Depending on the timing and surface temperatures, it could become quite messy and slippery late Sunday and Sunday night. Everything would melt Monday as the highs reach into the 40s.
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