Wednesday, November 9, 2011

Latest Update on the Weather

7:45am Update:  Heavy rain now moving through northern Ogle and DeKalb counties into Rockford and Belvidere.

An area of heavy rain is moving north along I-39 this morning, however, a dry slot (dry air in the mid levels of the atmosphere) is beginning to nose it's way into northern Illinois this morning and this will help to 'shut off' the heaviest rains.  While showers are still expected through this morning the heaviest rain will lift north into Wisconsin.  On the northwest side of the low is what we call a 'deformation zone'.  This is basically where there is convergence and divergence within the atmosphere and this is where we've had heavy snow falling through the overnight across Wisconsin and Iowa.  With the wrap around moisture later today, that's when we could get that wintry mix to occur.

The surface low is now just south of Rockford and will move into northeast Illinois within the next hour or two.  Winds will begin to shift to the northwest by mid-morning and that will help temperatures to fall back into the lower 40s by early afternoon and into the middle 30s by this evening.

Accumulating snow has been falling through Iowa for the majority of this morning where temperatures have remained cold enough to support all snow.  A change over from rain to snow is beginning to take place west of Dubuque as of 6:30am and this change over may begin to move east through the 8am hour.  I'm still expecting rain mainly over northern Illinois and southern Wisconsin through this morning with temperatures remaining in the 40s.  A rain/snow mix will likely occur in northwest Illinois with a possible change over to all light snow after noon.  A wintry mix can be expected for the rest as moisture wraps around the low.

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