Saturday, March 24, 2012

Riding The March Temperature Roller Coaster

Low pressure has moved off to the east, but no cold air has followed in behind it. The air is still relatively moist with dew points in the 50's.  So, it will remain mostly cloudy tonight.  As the temperatures drop off overnight, the dew points will be reached, and areas of fog will develop after midnight. The overnight low will be in low 50's. The fog will burn off shortly after sunrise on Sunday, and skies will become mostly sunny.  It will be a delightful day with  light northerly winds, and an afternoon high in the low 70's.  A cold front will edge southward across the Stateline during the afternoon into the evening hours.  No precipitation is expected with the passage of the front.  A large Canadian high pressure centered over northwestern Ontario will bring northern Illinois the coldest temperatures the area has had in about 2 weeks with temperatures dropping into the upper 30's.  Frost is not expected because clouds associated with a disturbance over the northern plains will spread southeast across the area overnight  There is a slight chance of some light showers toward daybreak over far northwestern Illinois.  An increasing pressure gradient will begin to develop between the Canadian high and the low pressure over the northern plains.  Northeasterly winds will pick up on Monday to 10-15 mph under mostly cloudy skies.  It will be a chilly day with a high only in the upper 40's with a slight chance of light rain showers. There is a fair, to a good, chance of showers and thunderstorms developing into northern Illinois with that system over the northern plains by  Monday night and Tuesday.  A warm front will move from southwest to northeast across the area on Tuesday boosting the afternoon temperature to near 70 degrees.  The system will drag a cold front quickly back through northern Illinois by evening.  It will be cooler, but still well above average, on Wednesday under mostly sunny skies.  A re-enforcing Canadian cold front will drop temperatures again on Wednesday night into the upper 30's.  It will be mostly sunny on Thursday with a high in the mid to upper 50's.  The Canadian ridge of high pressure will shift off to the east by Friday morning.  A warm front will develop from around Omaha, Nebraska southeast through northern Mississippi.  A disturbance associated with the front will pull Gulf of Mexico air up and over the front increasing clouds a setting the stage for a good chance of showers and thunderstorms by Friday afternoon.  Chances of showers and thunderstorms will continue until the passage of the warm front across into southern Wisconsin, which looks like around noon time on Saturday.  Once again northern Illinois will be bathed in unseasonably mild air with afternoon temperatures reaching the 70's.

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