Light snow falling now: Watch for slick spots

An upper level trough in eastern Iowa helped redevelop light snow early this morning.  This snow is now passing through north-central Illinois and south-central Wisconsin.  What I've noticed the past hour or so is the snow is expanding a bit in coverage and there has been a little enhancement with a few embedded snow bands.  While it's likely not going to amount to much it may be enough to cover the ground and slicken up your morning commute.  There was a little freezing drizzle overnight that had caused secondary roads, bridges/overpasses, sidewalks and parking lots to become slick, but the threat for this morning will remain the snow.

Visibility has dropped where the snow is falling so make sure you use your headlights while traveling.  The clouds will probably last through the better part of the afternoon.

Freezing Drizzle Tonight

The NWS office in Chicago has issued a special weather statement for the potential for freezing drizzle overnight. Although this freezing drizzle will not amount to more than 0.1", this will still be enough for tricky travel... Especially on untreated roads. Here is the NWS statement:


WINNEBAGO-BOONE-MCHENRY--OGLE-LEE-DE KALB-
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...WOODSTOCK...
...OREGON...DIXON...DEKALB...
SNOW TO END TONIGHT WITH PATCHY FREEZING DRIZZLE POSSIBLE...

LIGHT SNOW WILL CONTINUE THROUGH THE MIDNIGHT TIME FRAME TONIGHT
BEFORE SLOWLY SHIFTING EAST OUT OF THE AREA. WITH THE DEPARTURE OF
THIS SNOW...A PERIOD OF PATCHY LIGHT FREEZING DRIZZLE WILL BE
POSSIBLE ACROSS PORTIONS OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH THE EXTENT OF THIS FREEZING DRIZZLE AND THE
EXACT TIMING OF THIS TRANSITION REMAIN UNCERTAIN AT THIS
TIME...THE CHANCES FOR THIS LIGHT FREEZING DRIZZLE WILL BECOME
MORE LIKELY FOR AREAS ALONG AND WEST OF A ROCKFORD TO WATSEKA LINE
EARLY TUESDAY MORNING. WITH TEMPERATURES IN THE UPPER 20S...SOME
SLIPPERY SPOTS MAY FORM ON AREA ROADS AND POSSIBLY LINGER INTO THE
MORNING COMMUTE.

ANYONE PLANNING TRAVEL OVERNIGHT SHOULD BE AWARE OF SLIPPERY ROAD
CONDITIONS. BE ESPECIALLY CAUTIOUS ON ELEVATED ROAD SURFACES SUCH
AS BRIDGES AND OVERPASSES WHICH TYPICALLY SEE ICE FORMATION BEFORE
OTHER AREAS.

Snow chances this week

Two systems will impact our weather this week; the first has been bringing widespread snow across Iowa and Missouri early this morning.  This snow will continue to spread into Wisconsin and Illinois with accumulations nearing two inches or so.

The second is currently punching into northern Canada and will be with us late Wednesday night and Thursday. 



Probability of snow > 4" Wednesday



The track of the second one will be one to pay close attention to in the following days.  As this low moves into the southwest a surface low pressure system will develop along the Oklahoma/Texas panhandles and lift northeast Wednesday to near Chicago by Thursday morning.  As we may remember, lows that take this track could be big snow producers.  With this type of track the heaviest snow band would set up just northwest of the surface low track placing the snow across north-central and northeast Iowa, southeast Minnesota and central Wisconsin.  Warm air lifting northward in the upper levels and surface would likely leave us with rain or a rain/snow mix Wednesday night.  Should this low track further south in the coming days then the heaviest snow band would shift further south as a result leaving us with accumulating snow; possibly over 4" or more.  Stay tuned!

Snow moves in later today

High pressure dominated the weekend with blue skies and chilly temperatures.  This morning clouds have replaced the clear skies and those clouds will continue to thicken through the morning and afternoon.  Light to moderate snow has been moving through Iowa all morning with accumulations ranging between 1" to 3". 

Looking at current surface observations the snow is now falling from Cedar Rapids up through Waterloo and this snow will continue to move northeast and likely enter our far northwest Illinois counties later this morning.  All of us will experience snow going into the afternoon and for the evening commute.

While there are no advisories for the immediate Stateline area, there are Winter Weather Advisories extending through much of the middle of the U.S.  Warm, moist air out ahead of an upper level low will continue to advance north and east.  The forecast sounding (atmospheric profile) from Davenport, IA this morning still shows a fairly dry layer of air above the surface but the precipitation that has been falling so far out west has helped to quickly saturate the air mass and allow the snow to fall and accumulate.  Totals from the snow could near 2", but if a heavier bout of snow falls some of those totals may increase a little.  The snow will last into the overnight and may mix with a little freezing drizzle as dry air once again moves into the system.  This will linger into Tuesday morning with mostly cloudy skies expected for the remainder of the day.

The commute this morning will be fine but as you head home from work or school later this afternoon and evening roadways may become a little slick with the freshly fallen snow.

The arctic air mass has moderated considerably as it continues to move toward the east, It will be over northern Alabama by midnight, and still is the main weather maker over the eastern half of the nation. Skies will be clear across northern Illinois early tonight, but high clouds from a system over the southern plains are already moving east though Iowa.  So, clouds will edge into the Stateline later tonight. The first clouds will be high thin cirrus, and may hardly be noticeable before daybreak. The overnight low will be in the low to middle teens. It will quickly become overcast on Monday morning as clouds lower and thicken. The surface air will initially be very dry, so it will take some time to saturate the atmosphere down to the surface delaying the start of snow until mid afternoon on Monday, although there could be a few flurries before that.   The high temperature will be in the low 30's, and around 1" of snow could fall by 6 pm Monday evening.  It will continue snowing lightly on Monday night with to another 1" possible by daybreak on Tuesday morning.  Flurries may linger off and on through the morning on Tuesday under clouds skies.  The clouds will start to thin out on Tuesday afternoon, and there may be some breaks allowing some sunshine by later on in the afternoon.  Weak high pressure will take charge on Wednesday with partly sunny skies and temperatures reaching the upper 30's by mid afternoon.  A southern stream low pressure system will begin it's approach on Wednesday night.  Enough warm air will be in place so that precipitation that falls could be either rain or snow or a rain/snow mix.  However, at this time it looks like any accumulating snow will be to the north across Wisconsin later on Wednesday night into Thursday.  That system will depart off to the east as a sprawling Pacific high takes control of area weather on Friday.  Temperatures will continue to run a little above season averages through next weekend.

Not Cold For Long

Arctic high pressure over the central plains continues to feed very cold air across the Stateline tonight. It will be clear overnight with northwest winds slowly diminishing. The low will be around 7 degrees around daybreak. The winds will be from the northwest 10-18 mph. That is still rather brisk, but not as strong as the past couple of days. With temperatures in the single digits, wind chills will drop to 0 to 10 below late tonight, and into the daybreak hours on Sunday. Sprawling high pressure from Canada will be situated over Arkansas early Sunday morning and will dominate the weather over the eastern 3/4 of the country.  So, it will be sunny on Sunday with a high temperature around 27 degrees.  The wind will be westerly at 10-20 mph.  The high pressure will move into Mississippi by evening, and into  Georgia by 6 am Monday morning.  A light southwesterly wind will develop on Sunday night.  It will not be quite as cold with a low early Monday morning around 13 degrees.  Moisture moving northward from the Gulf of Mexico will move into the area on Monday making skies cloudy.  There will be a chance of light snow during the morning, and light snow will be likely on Monday afternoon into the evening hours.  There could be a little accumulation with this system.  A trough of low pressure will continue the chances of light snow and snow showers through early Tuesday morning.  It will be milder on Tuesday with a high near 36 degrees .  On Wednesday it will be partly sunny with a high near 40 degrees, but a new system from the southern stream will begin to hook toward the northeast out across the southern plains on Wednesday night.  With milder air in place, the precipitation could be a mix of rain and snow on Wednesday night and Thursday.  The low pressure system looks like it may pass northeast across Illinois on Thursday.  With a little colder air following in behind the low, there could be some flurries on Thursday night.   A sprawling high pressure fom the Pacific will dominate the weather across most of the country on Friday and Saturday.  High temperatures will be in the mid to upper 30's with partly to mostly sunny skies leading into next weekend.

Light snow here...Heavy snow further east

Back edge of the more moderate snow band is now moving through Winnebago county.  Totals remain under an inch, but what's causing all the trouble this afternoon is the blowing snow.  It is blowing over roadways and has caused near zero visibility at times.  There is a little light snow being reported behind this band but it isn't much.  The winds will remain through the night so the snow will continue to blow.

11:20 am Update: Light snow will continue through the afternoon as an arctic cold front passes.  A few heavier bands of snow have developed north of Milwaukee and those are moving south likely affecting southeast Wisconsin early this afternoon.  Totals within that band so far have ranged between 2" to 3".  Further west and southwest totals will be closer than an inch.  Some of the heavier snow may clip Boone and McHenry counties, but the big snow will be closer to Chicago and northwest Indiana.

It doesn't take a meteorologist to note where the cold front is this morning as temperatures ahead of the front are in the low 30s and back in Iowa they have been falling through the low teens all morning.  There is just a little lag in temperature drop behind the front but once winds shift more to the northwest that cold air will be in full force.  While we'll likely see a half inch at most the Fox Valley area, Chicago and northwest Indiana will be dealing with a little more. 

A Winter Weather Advisory has been issued for Chicago and surrounding counties to the north and south while a Lake Effect Snow Warning has been issued for extreme northwest Indiana.  Winds will initially turn northwest behind the front but once it completely clears the southern shores of Lake Michigan a more north wind will be found.  This north wind will be traveling down the entire fetch of Lake Michigan picking up moisture and generating instability as it does so.  The waters of Lake Michigan are relatively mild, compared to where they typically should be this time of year, and there is barely any ice to be found due to the recent mild weather.  The cold air moving over top the warmer waters have the potential to produce some pretty hefty lake effect snow bands across northwest Indiana; totals could reach over six inches.  If travel takes you east later this evening or tonight conditions may turn a little dangerous, especially if the heavy snow bands develop.