Snow spreading across west, north suburbs

Radar and surface reports indicate that snow has spread across north central, and portions of northeast Illinois. At 3:00 PM CDT the snow was along and west of a line from Mundelein, to Arlington Heights, to Elgin, to Peru. The snow is expected to continue spreading across the metro area heading into this evening.

Where the snow is falling, temperatures are running in the mid 30s so most of what is falling will melt on contact. Also, visibilities are generally around 2 miles.

Heavier snow, with temperatures hovering near freezing and visibilities near 1 mile are reported across northwest Illinois. Some slushy accumulations may begin later this afternoon, mainly on grassy areas. Roadways heading into the evening rush are expected to remain wet.

Tim’s Weather World: The fickleness of forecasting snow

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We’ve been watching the models for signs of significant snowfall this Sunday ever since they hinted at the possibility earlier this week.  Just yesterday the European model was touting a robust snow producer that could lay out up to 8″.  The latest model solutions have pulled way back.  The European model is now suggesting 1-4″ is more likely with the city and areas southward getting the low end of the range or barely anything at all.  The GFS model didn’t waiver as much also sticking to a similar solution of under an inch in the city and southward.

Tim ECMWF Snow Accum.

Tim DMA GFS LONG RANGE Snow Accum.

While changing snowfall forecasts can be frustrating they are to be expected.  Snowfall amounts are one of the most difficult things to forecast.

There are many factors that influence snowfall forecasts.

  • Duration of the storm-When will it begin? How long will it last?
  • Track of the storm-a 100 mile wobble could mean the difference between flurries and a foot of snow.
  • Lake effect enhancement-will the storm be supercharged with a wind off the lake adding to totals?
  • Snow to liquid ratio-colder storms could fluff up to 20″ of snow or more from one inch of liquid while 10″ snow is the average.
  • Ground temperature-a warm ground could melt snow initially lowering the total accumulation.
  • Moisture-will thunderstorms in the warm sector suck up moisture that could have added to snowfall totals?

In other words, stay tuned because the forecast could change and probably will.

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Tim’s Weather World: A Sunday smattering or smackdown?

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What a start to the snow season!  We have had at least flurries 8 of the last 9 days and we are forecasting at least flurries for 5 of the next 7 days.  O’Hare has seen just under 10″ of snow for the season.  That nearly doubles what we typically see through this point of winter.  Last year we only had a trace of snow so far.

After a quick shot of .5″ to 1″ of snow thi smorning the next significant snow will probably fall on Sunday.  The computer model solutions aren’t exactly in agreement at this point.  The European model (see image below) is suggesting a more robust storm with total accumulation by Sunday night at nearly 10″.  About an inch of that will fall prior to the Sunday storm.  The GFS model (see image below) is spitting out 1.7″ total accumulation through Sunday night with .4″ coming prior to the Sunday storm.

Tim Midwest - ECMWF 10 Day Snowfall Accum

Tim Midwest - GFS 10 Day Snowfall Accum

Either way, the prospects for a white Christmas are excellent.   Both models agree cold air will follow the snow so any snow that falls should stick around for several days.

Fun snow fact of the day…

As of yesterday, 46% of the contiguous US had snow cover with an average depth of 3.5″.

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Tim's Weather World: Dramatic December temperature drop coming

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Meteorological winter* started Sunday with temperatures at or just above average for early December.  40° is the average high for this time of year. Today will also be at or above average for most.  Tuesday should be the warmest day of the week with highs in the lower 50s or what we typically see in early/middle November.  Check out the forecast temperatures from the GFS model for 5 PM Saturday.  Brrrrr…….

 

Tim Midwest Highs NAM

Enjoy it while you can because Arctic air will come crashing in by the end of the week with the coldest air of the season so far.  We will barely climb into the lower 20s for highs Friday and Saturday with wind chills dipping below zero at times.

 

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Once the cold air arrives it looks like it will stick around for a while. The 6 to 10 day forecast from the Climate Prediction Center has us outlooked for below average temperatures (see image above) during the second week of December.  So if you still have holiday decorations to put up outside you better get to it soon.

 

*December, January and February are the three coldest months of the year.

 

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Slightly warmer air en route for coming week

Cold temperatures have been the rule during the latter half of November. Persistent, northwesterly jet stream flow has allowed only one of the past 11 days to average above normal. A temporary shift in upper-level winds is forecast to break the current spell of chilly weather. Daytime temperatures over the weekend are forecast to peak near, or just above the normal high of 40 degrees. Slightly cooler temperatures are expected to settle back into the area Monday, before a more pronounced southwesterly jet stream flow becomes established by midweek. Temperatures much of the first week of December are forecast to average about 8 degrees above normal, reaching well into the 40s. Medium-range forecasts suggest the milder weather will be short-lived. Much colder air is expected to arrive next weekend.

Lake effect snow in the Michigan and Indiana snowbelt won't ease until tonight

UPDATE 6:00PM:  A few snowfall totals from across southwest Michigan and northern Indiana as of 6:00PM:

 

15.0″  Spinks Corners, MI

12.0″  Sodus, MI

12.0″  Berrien Springs, MI

8.0″   Mishawaka, IN

7.0″   Benton Harbor, MI

 

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UPDATE 10:30AM:  Snow showers are expected to intensify over northwest Indiana between Noon and 1PM EST as a new plume of heavy lake effect snow moves south off Lake Michigan.

 

Up to six inches of snow is already on the ground in a few locations, with another two to eight inches of accumulation expected this afternoon and evening.  Winds will ease overnight, resulting in fewer and less intense snow showers after Midnight.

 

The most treacherous driving conditions were reported in Berrien county along Interstate 94 between St. Joseph and Hartford, Michigan.  Numerous accidents have been reported near Coloma and Watervliet, where motorists are reporting  traffic in both the eastbound and westbound lanes of I-94 are at a standstill.

 

Snowfall totals as of 10:00AM:

6.0″  Niles, MI

6.0″  Tyner, IN

6.0″  Buchanan, MI

5.0″  South Haven, MI

3.6″  4mi NW of South Bend

3.5″  2mi NE of South Bend

2.0″  Mishawaka, IN

2.0″  Union Mills, IN

2.0″  Westville, IN

1.3″  La Porte, IN

0.9″  2mi W of Valparaiso

0.7″  Stevensville, MI

 

BELOW: Radar at 10:30AM CST indicates a plume of heavy lake effect snow over northern Berrien county drifting south toward I-80, I-90 and South Bend.

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8:00AM:  Moderate to heavy lake effect snow bands will continue to have an impact on holiday travel today just 35 miles east of downtown Chicago.  Travel will be slow and slippery in spots along Interstates 90 and 80, from I-65 ( just east of Gary) to roughly 20 miles east of South Bend, Indiana.  On Interstate 94, the snow will impact travel from I-65 to Paw Paw, Michigan.

 

A Lake Effect Snow Warning continues for La Porte, St. Joseph (IN), Starke, Marshall and Berrien Counties.  The warning runs until 11PM CST Wednesday night.  Snow accumulation is expected to range from four to ten inches in the warning counties, with locally heavier totals of 12 or more inches.  A few of the cities included in the warning are South Bend, Michigan City, New Buffalo and La Porte.

 

In addition to the warning, a Lake Effect Snow Advisory continues for Porter, Jasper, Pulaski and Fulton counties in northwest Indiana through 11PM CST or 12AM EST.  One to six inches of fluffy lake effect snow is likely in the advisory area, with locally heavier totals in excess of six inches. In Porter county,  the heaviest totals will occur in the eastern half of the county.

 

For Chicago and northeast Illinois, little or no snow is expected today.

 

BELOW: Counties in dark green are included in the Lake Effect Snow Warning.  Counties shaded in light green are under a Lake Effect Snow Advisory.

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A few flakes will fly in Chicago tonight, lake effect snow update

A Lake Effect Snow Warning continues for La Porte, St. Joseph (IN), Starke and Berrien Counties.  The warning runs from 11PM CST tonight until 11PM CST Wednesday night. Snow accumulation is expected to range from four to ten inches in the warning counties, with locally heavier totals of 12 or more inches.  A few of the cities included in the warning are South Bend, Michigan City, New Buffalo and La Porte.

 

In addition to the warning, a Lake Effect Snow Advisory has been issued for Porter, Jasper, Pulaski, Fulton and Marshall counties in northwest Indiana from late tonight through Wednesday.  One to six inches of fluffy lake effect snow is likely in the advisory area, with locally heavier totals in excess of six inches. In Porter county, this advisory replaces the Lake Effect Snow Watch, where the heaviest totals will occur in the eastern half of the county.

 

For Chicago and northeast Illinois, occasional light snow or flurries are expected this evening in association with yet another cold front that will exit the area after Midnight.  Any accumulation tonight in northeast Illinois will be minor, ranging from a dusting to 0.5″.

 

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BELOW: Counties in dark green are included in the Lake Effect Snow Warning.  Counties shaded in light green are under a Lake Effect Snow Advisory.

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Narrow band of heavy snow to develop just east of Chicago Wednesday

Treacherous travel conditions are expected late tonight and tomorrow along a narrow stretch of  I-94, I-90 and I-80 in southwest Michigan and northern Indiana.  A narrow plume of heavy lake effect snow will develop tonight and intensify tomorrow, one of the busiest travel days of the year.  This 10 to 20 mile wide band of heavy snow will set up over La Porte, Berrien and St. Joseph (IN) counties resulting in reduced visibilities, down to 100 feet at times, as well as very slick road conditions.

 

Thanksgiving travelers passing through these counties in southwest Michigan and northern Indiana should be prepared for rapidly changing and varying road conditions.

 

BELOW: Forecast map for 3PM Wednesday illustrating the expected location of a narrow band of  heavy lake effect snow between Valparaiso and South Bend.

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Lake Effect Snow Warning for portions of the Michiana Snowbelt

A Lake Effect Snow Warning has been issued for La Porte and Berrien Counties.  The warning runs from 11PM CST tonight until 11PM CST Wednesday night. Snow accumulation is expected to range from four to ten inches in the warning counties, with locally heavier totals of 12 or more inches.

 

In addition to the warning, a Lake Effect Snow Watch remains in effect for Porter and St. Joseph (IN) counties from Midnight CST tonight until 6PM CST Wednesday.  One to six inches of fluffy lake effect snow is likely in the watch area, with locally heavier totals in excess of six inches.

 

Mike Hamernik on Twitter @Mike Hamernik

 

BELOW: Counties in green are included in the Lake Effect Snow Warning.  Counties shaded in blue are under a Lake Effect Snow Watch.

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Burst of snow today ahead of yet another cold front

UPDATE 1:00PM:  A band of light snow continues to drift from north to south over the Chicago area early this afternoon.  Embedded within this band of light snow are a few pockets of moderate snow. Up to one inch of accumulation is expected by evening for most of the Chicago area.  A few isolated locations may see 1.5 inches of snow.

 

Untreated roads are starting to become slippery.  Several weather related accidents have occurred in Chicago’s northern suburbs as well as southern Wisconsin.

 

Here are a few snowfall reports as of 1PM:

 

2.0″  Cedarburg, WI

2.0″  Edgerton, WI

1.6″  Madison, WI

0.8″  Capron, IL

0.7″  Milwaukee, WI

 

 

BELOW: An accident on eastbound I-94 near Kenosha has traffic heading toward Chicago at a standstill.

 

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11:00AM: Snow is starting to break out across northern Illinois this morning along and ahead of an approaching cold front located in southern Wisconsin.  Some minor snow accumulation is likely, with amounts ranging from a dusting to perhaps nearly 1 inch in a few locations.

 

The snow, coupled with temperatures that will hover at or slightly below freezing (32F) for the rest of the afternoon, may result in a few slick spots on area roads.

 

In southern Wisconsin where snow started falling early this morning, untreated roads are slippery in stretches.

 

BELOW: Snow partially covers Interstate 94 as well as a frontage road near Pleasant Prairie and Kenosha, Wisconsin.

 

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