Sunday, February 27, 2011

Fast Moving Storm System Will Provide a Mixed Bag Overnight

Low pressure organizing over the southern plains will move to western Kentucky by 6 am on Monday morning.  A warm front lies across central Illinois this evening, and there is  very warm, moist unstable air to the south of the front.  A strong low level jet from the south is expected to over run the warm front tonight setting the stage for a wild night weatherwise.  Preciptiation has already begun (as of 7 pm) in the Stateline in the form of freezing drizzle.  As the flow increases from the southwest the freezing drizzle will likely increase in intensity and become freezing rain for a time.  There will be enough instability for thunderstorms to get going later this evening with the potential for locally heavy rainfall in the 0.75" to 1.00" range ovenight.  As the colder air comes in later tonight the freezing rain will mix with sleet and snow, and become all wet snow after midnight.  Accumulations of snow and sleet are anticipated to be in the 2" to 4" range by 5 am on Monday morning.  So, with the weather conditions that are expected overnight, a WINTER WEATHER ADVISORY has been issued for Winnebago, Boone, Ogle, Lee, and DeKalb counties from 9 pm tonight until 6 am on Monday morning.  This storm system is a fast mover, so all of the precipitation should be done by 6 am on Monday morning.  With drier air coming in behind the departing storm system skies will be partly cloudy by 8 am, and mostly sunny in the afternoon.  Temperaures will be a little on the cool side for this time of year with a high only around 30 degrees along with a northerly wind at 10 to 15 mph.  With clear skies on Monday night the temperature will drop to the middle to upper teens.  The cool high pressure will move quickly to the east Monday night and winds will shift to the south on Tuesday, and with mostly sunny skies the afternoon high will top out near 40 degrees.  Tuesday is my pick for the best day of the coming week, weatherwise.
By Meteorologist
Eric Nefstead

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