Light Snow and Bitter Cold

After suffering through bitter cold temperatures  this week, we get a bit of a break today with high temperatures warming into the mid and upper 30's. This happens as a warm front lifts across northern Illinois allowing warmer air to advect in. However, the associated low pressure and cold front with this system won't let the 'warmer' weather stick around.

As the low settles overhead this evening, light rain and drizzle will be possible. Temperatures will be hoovering very close to freezing, and if temperatures dip to 32° or lower tonight freezing drizzle is also possible. The cold front will switch our winds on Friday to the northwest ushering in colder air. As light rain, south of the Stateline, lifts north it will switch to a light winter mix for nothern Illinois and southern Wisconsin. As temperatures fall through the morning, the light mix will switch to light snow. With not a lot of moisture available on Friday, we won't see much in terms of accumlation, however could still see enough to allow for slick areas on roads. The light off and on snow showers will continue into late Friday afternoon, however then end overnight.

Behind the departing low pressure system, an arctic high pressure will then move in. This keeps weekend weather quiet, but very very cold. The high will usher in frigid arctic air into the Stateline, dropping temperatures into the 20's on Saturday. But the heart of the cold settles in for Sunday and Monday. High temperatures will only reach the low single digits and overnight lows will fall below zero.With northwest winds in place and subzero lows, this will bring wind chill readings down to -20° to -30­° for some. This would prompt a Wind Chill Advisory and possibly a Wind Chill Warning. It's still too far out to say for sure, but something we will be keeping an eye on as we head into the weekend, and of course we will keep you updated.

Recent Cold Snap Causing Ice Jams on Local Rivers

With daytime temperatures remaining below freezing and overnight lows dipping in the sub-zero range, ice has quickly formed on local rivers. 

Ice jams were causing river rises on portions of the Rock River near Dixon in Lee County and Latham Park in Winnebago County.  Due to these ice jams, river levels could fluctuate rapidly with little to no warning.  If you live near one of these areas and are in a flood prone region, stay alert for possible flooding over the next couple of days.  Especially as the ice begins to break up with the rise in temperatures.

Lee County Emergency Management actually reported an ice jam from Dixon, downstream to near the Whiteside County line.

Even Colder Air This Weekend?

Temperatures of late have been very cold across the region. Sunday was spent in the single digits, Monday was spent in the teens, and today has featured highs near 10°. This evening, temperatures are dropping into the single digits with wind chills remaining well-below zero through the entire night. With the coldest stretch of weather thus far this season affecting the area, a popular question has been, "How much longer will it last?" There is a light at the end of the tunnel to end this week, but soon thereafter, arctic air will move back into Northern Illinois and Southern Wisconsin.

Temperatures on Wednesday will reach the lower 20's before warming into the balmy 30's on Thursday and Friday. Some locations south of Rockford may flirt with 40° on Friday. With that system comes some rain and snow, but snow accumulations look light at this time with much of the moisture from our system being pulled to the East Coast where a stronger low is going to develop.
The coastal low is going to take some moderate to heavy rain and snow into the Northeast and New England on Saturday. The more important story for the Stateline regarding this weekend's storm system is the reinforcement of arctic air that will stream southward from Canada on Saturday night. Each time a low pressure system passes by, the winds turn northerly, and that allows colder air to filter into the region. This explains why each time we see snow associated with a low, it typically gets colder after the snow comes to an end. That will hold true this weekend, but the colder air may be even colder than what we have now.

This next arctic air outbreak will likely bring low temperatures in the 10° to 0° range for a string of 2-3 mornings. It also appears as though forecast models want to bring down enough cold air to hold our daytime highs in the single digits on Sunday and Monday. However, it is important to note that we are still a good four days away from this arctic plunge. Therefore, things have time to change, which means the magnitude of the cold air could decrease, meaning temperatures may not get quite as cold as currently advertised.

Nonetheless, it does look like a reinforcing shot of arctic air is likely this weekend into next week with air that is as cold as what we are experiencing now, if not colder.

Tuesday's Weather

After 1.4 inches of snow fell in Rockford yesterday, now we have to deal with blowing and drifting snow. Strong winds will allow the light and fluffy snow we received to be easily blown around, reducing visibilities and causing roads to be slick in spots. You'll want to use caution and allow for extra time to get to where you need to go. A current look at Illinois' road conditions map shows there are still many roads that are snow and ice covered.

Temperatures today will stay in the single digits with chills well below zero. If you have to head out make sure you have a full tank of gas, a charged phone, food and water, and warm clothes or a blanket in case you do get stranded.

You can monitor current road conditions here.

Tale of Two Storm Tracks

With temperatures remaining below freezing through the middle of the week, any precipitation that falls will be in the form of snow.  First round of it coming through Monday night and the second round may arrive as early as Wednesday afternoon.  Each will bring minor accumulations with it, but continued cold temperatures.

By the end of the week, our focus shifts to a storm system still well off in the Pacific Ocean.  This storm will help shift our jet stream pattern from the frigid northwest flow that has brought us the below zero temperatures and wind chills, to possibly temperatures warming above freezing and even getting close to 40 degrees!  But it all depends on the storm track.

A couple scenarios could play out for the Thursday through Saturday time frame.  The first scenario keeps our jet stream pattern in what we call a 'split-flow'.  With the northern branch of the jet stream developing an area of low pressure and passing it the northwest of Northern Illinois and Southern Wisconsin, with a secondary low developing to the south and moving into Indiana and Michigan.  This type of storm track would produce a rain to rain/snow mix, possibly as early as Thursday night before switching over to lighter snow Friday night into Saturday.

The second scenario would keep the southern low stronger, but bypass us a little further to the east shifting the heaviest snowfall east of Northern Illinois and Southern Wisconsin.

Following the weekend, it does turn cold again with the below average pattern sticking around through the end of January.

Slick Roads Possible through Midweek

Snow totals on Saturday didn't amount to much, about an inch across the Stateline, but it was just enough to make roads a mess. Now most highways, interstates, and main roads are clear but secondary and rural roads are still partially snow and ice covered. If you are heading out on one of those types of roads, you'll want to allow extra time to get to where you need to go.

While temperatures are forecast to stay below freezing this week, and with more snow on the way, those roads won't see much improvement. Rock salts used to treat roads in winter are less effective when temperatures stay below 20 degrees. Temperatures will stay below 20° through Thursday morning.

We will also add a little more snow to the roads later today with a fast moving clipper system that will drop in from Canada, dive through the Dakotas and Iowa, and will swing into northern Illinois. Overall about a half to an inch of snow is expected this afternoon and evening. With not much moisture, snow to liquid ratios will be high. This means that dry and fluffy snow will be falling, allowing it to accumulate quickly on roads, allowing them to be slick.

The snow will be done with by Tuesday morning, but winds will really pick up behind the departing low pressure system. Because the snow is on the dry fluffy side, it will be easy for those northwest winds to blow the snow around. Winds will gust from the northwest at 20-30mph late tonight and tomorrow morning. You'll want to allow for extra time to get to your destination tomorrow morning with the blowing snow causing some road issues. Chills tomorrow will be as low as 15 below zero.

Keep the gas tank full, your phone charged, and keep extra coats and food in the car in case you get stranded. Temperatures warm closer to 30 degrees by the end of the week.

Dangerous Roads and Wind Chills through Monday Morning

Highs Sunday were reached very early in the day, but have been falling ever since.  And as we put a close on our Sunday afternoon, temperatures have fallen into the low single digits with wind chills well below zero.

Gusty west/northwest winds will continue through early overnight holding wind chills anywhere between -11° and -20°.  And even though the winds will lighten up slightly by Monday morning, overnight temperatures will fall as low as -5° in outlying areas!  With temperatures this cold, frostbite can happen in a short amount of time - especially during the morning hours.

Another hazard going into Sunday evening will be the roads.  Secondary and rural roads, especially east and southeast of Rockford, are still partially snow and ice covered.  And with little opportunity for temperatures to warm the next couple of days, those roads will remain slick.  Please use caution if your commute takes you on any roads outside of city limits.

There is a chance for snow Monday and Monday night with amounts remaining under an inch.  Winds will also increase by Tuesday morning, so expect some roads issues again.