Friday, January 2, 2015

Arctic air next week following weekend storm

A Winter Weather Advisory has been issued for Rock and Walworth counties in southern Wisconsin and for Winnebago, Boone, McHenry, Ogle, Lee and DeKalb counties in northern Illinois beginning early Saturday morning.  A mix of sleet & snow is likely tonight with little accumulation with freezing rain developing by Saturday afternoon.

After finishing the 8th coldest year on record in Rockford, Mother Nature has decided to start the first full week of the new year off with some very cold air.  It's going to be a one, two, three punch over the next week with the first round coming this weekend.

As was discussed in an earlier blog post (read it here), a winter storm is set to take shape across the Plains and Midwest.  That will be followed by bitter cold for the start of school next week, followed up by another bout of snow and then more cold!

Weekend system still looks on track with a mix of snow, sleet, freezing rain and rain coming in by Saturday afternoon.  An initial surge of moisture with a disturbance moving through Iowa may bring a light mix of snow & sleet across northern Illinois and southern Wisconsin Saturday morning.  Little accumulation is expected.  By late morning and afternoon, temperatures will warm very close to the freezing mark which could increase the threat for freezing rain during the afternoon in northern Illinois.   The temperature profile throughout the atmosphere continues to show a shallow warm layer a few thousand feet above with south winds, but surface temperatures will range from roughly 32° to 35°.  While it may be raining up above, it could freeze on contact causing a thin glaze of ice to form.  Should we receive freezing rain, totals near 0.10" to 0.15" will be possible.  Just enough to cause slick roadways.  Accumulating snow is still possible Saturday night before ending Sunday morning.  Snow accumulations by Sunday morning could be 2" to 3".

Travel will become impacted throughout Saturday, especially if we receive more freezing rain than just rain.  So keep that in mind if you're going to be out. 

Behind this system, cold air is set to arrive with a vengeance Sunday afternoon.  Temperatures will fall throughout the day dropping to below zero by Sunday night.  Winds will also coming howling in from the north Sunday and Sunday night.  With the actual air temperature falling below zero, this puts wind chills Monday morning in the -25° to -15° range.  A rude awakening for students heading back to school. 

Another round of snow is expected Monday night and Tuesday with a clipper system.  This, too, has the potential for accumulating snowfall which will only aid in Wednesday's extreme cold!  High temperatures on Wednesday will only be 3° with winds chills down to -25° during the day!  Thankfully it won't last as we'll get back into the upper 20's by the end of the week.

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