Ice Storm Underway for Chicago

A storm system is moving across the Upper Midwest this evening with warm air aloft overrunning sub-freezing air at the surface, and resulting in a freezing rain event for the Chicago Metro Area.  Precipitation is already spreading into the region this evening, as can be seen on the recent precipitation-type radar image, with red colors indicating freezing rain.  You’ll even notice there have been some recent lightning strikes southwest of the area toward Peoria!



Freezing rain will continue through the overnight period before tapering off between roughly 6am-8am Wednesday morning.  Ice accumulations will make for a hazardous Wednesday morning commute, especially on bridges and elevated surfaces.  Some parts of the metro area could see ice accumulations of 1/4″ or higher.  The next image from the HRRR model shows projected ice accumulations overnight (image source: College of DuPage).



In addition to difficult road conditions, downed trees and power lines will also be a hazard, as these type of storms usually result in widespread power outages.  

After the freezing rain comes to an end Wednesday morning, temperatures will slowly rise from near freezing into the mid/upper 30s for the remainder of the day, which should allow for improvement on the roadways despite skies remaining cloudy. 

The next round of precipitation will then arrive Wednesday night and Thursday, but fortunately this will be all rain (of the liquid variety), with temperatures warming up significantly into the 40s during the day Thursday.


Snow returns to Chicago tonight with impacts for the Monday morning commute

A low pressure system approaching from the northwest will bring the next round of winter weather to the Chicago metro area from late tonight through Monday morning.  Looking at this afternoon’s water vapor satellite image, we can see moisture from this approaching system currently pushing into Minnesota and Iowa (image source: College of DuPage).



This will be a fast-moving but potent system with about 6-8 hours of heavy snowfall expected overnight.  The heaviest period of snowfall will be from about midnight through sunrise with snowfall rates of 1″/hour or higher expected at times.  The next image from the HRRR model shows the projected radar reflectivity at midnight tonight, with widespread snow filling in across the Chicago area (image source: College of DuPage).



Snow that falls will easily accumulate on all surfaces given the cold temperatures in place.  However, it should be noted that a significant warming trend will occur overnight as warm air pushes in from the south.  Temperatures will rise from the low teens at around midnight tonight into the low 30s by mid-morning Monday. 

Toward the back edge of the main area of precipitation Monday morning, we could even see precipitation briefly change to light freezing rain, before a cold front arrives and temperatures quickly drop again.  Lingering scattered snow showers will continue through the day Monday, but most of the accumulation will occur overnight.

Total snowfall amounts across the greater Chicago area overnight are likely to range from 4-7″ for most areas, with significant road impacts expected during the Monday morning commute.  Heavier precipitation and colder air with higher snow to liquid ratios will exist farther north, so across the northern suburbs to the Wisconsin border, snowfall amounts look to be more in the 5-10″ range.

In addition to snowfall, winds will be gusty from the south at 15-25mph with gusts to 30mph overnight through Monday morning, becoming northwesterly with similar speeds Monday afternoon.  As a result, areas of blowing and drifting snow can be expected.

Following this storm, a well advertised blast of arctic air will arrive with record cold temperatures expected for the middle part of the week, including dangerous wind chills.

Winter storm to impact Chicago area tonight

An impressive storm system moving across the Central U.S. will impact Northern Illinois and the Chicago metro area tonight, bringing significant snowfall to the region.  The center of the low pressure system will be tracking well south of the area, but strong south/southeasterly flow will transport abundant moisture northward to bring snow to the region.

The onset of snow looks to begin across the Chicago area right around rush hour, which could impact the evening commute as snow should easily accumulate on pavement through this event.  The image below shows the HRRR-model simulated radar reflectivity, which projects snow to be reaching Chicago around 6pm local time (image source:



A steady snowfall can be expected for Chicago metro from early this evening through Saturday morning, with many areas likely to pick up 6″ or more of snow.  In general, the heaviest amounts are expected north of I-88, but banded snowfall could result in varying amounts.

Road conditions will quickly deteriorate tonight through Saturday morning, and strong winds from the east/northeast at 15-25mph with gusts to 35mph will result in areas of blowing and drifting snow.  The heaviest snow should come to an end during the morning hours Saturday with additional lingering light snow showers.

However, the potential for lake effect snow will arrive from late Saturday through early Sunday, with additional snow accumulations possible during the overnight period Saturday night-Sunday morning.  The additional lake effect snow along with breezy north/northeast winds will continue to impact travel conditions through Sunday. 

Snowfall should eventually come to an end by Sunday afternoon or early evening, but cold air arriving Sunday night will keep high temperatures in the teens on Monday.