by Mike Hamernik twitter @Mike Hamernik
Calm winds and clear skies overnight have led to patchy dense fog as well as a heavy frost this morning. The frost is resulting in slick spots on bridges and overpasses. Fog is especially thick in northwest Indiana where visibility is limited to just a few hundred feet along stretches of Interstates 80, 90, 94 and 65. The fog should quickly dissipate by 9AM.
RIGHT: Low lying dense fog in Akron, Indiana shortly before 7AM
by Mike Hamernik twitter @Mike Hamernik
UPDATE 9:05PM: Conditions are starting to improve as snow tapers over the entire Chicago area. Snow from the storm system will completely exit northern Illinois by Midnight. After Midnight, northeast winds off Lake Michigan are expected to stir up lake effect snow that will impact Lake(IL), Cook, eastern Will, and Lake(IN) counties.
Some additonal accumulation from lake effect is likely in lakeshore communites, but won't exceed one to two inches in any one location.
RIGHT: Forecast map for 5:25AM Saturday showing a plume of lake effect snow impacting eastern Cook and Will counties.
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UPDATE 7:55PM: Today's snowstorm continues to wind down. Visibilites are up, and the latest radar imagery shows the heaviest snow has moved east of Chicago into Michigan, Indiana and Ohio. We're right on track for a total snowfall accumulation of 5" to 8" for a large majority of the Chicago area. A few locations will end up with close to 9".
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UPDATE 7:10PM Visibility at Chicago's O'Hare Airport is up to 2.5 miles, and indication that the storm is beginning to wind down. We still have a couple more hours of snow on the way, but it won't be nearly as heavy as it was this afternoon.
Snowfall totals through 7PM
6.9" Homewood
6.7" Bollingbrook
6.5" Naperville
6.1" Joliet
6.0" Oswego
5.5" Chicago- Jefferson Park
5.2" Winnetka
3.8" Zion
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UPDATE 6:30PM: Light to moderate snow will continue across most of the Chicago area through 9PM this evening before tapering to flurries between 9PM and Midnight. For the first time since Noon, there are no Chicago weather stations reporting heavy snow.
Snowfall accumulations thus far range from 3.5 inches to almost 7 inches. An additional one to three inches is possible before the snow finally ends overnight.
Lake Shore Drive is open, however no CTA busses are operating on roadway this evening.
Tonight's game between the Chicago Blackhawks and the Florida Panthers has been delayed from 7:30PM to 8:00PM. The Florida Panthers team bus was stuck in traffic, and just arrived at the United Center minutes ago.
ABOVE/RIGHT: Radar snapshot taken at 6:30PM
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UPDATE 6:05PM: Road conditions remain treacherous as plows and salt trucks struggle to keep up with today's storm due to heavy traffic. Complicating matters is the fact temperatures range from 15 to 20 degrees above zero, well below the freezing mark. Chemicals spread on pavement to melt ice and snow don't work nearly as well at 20 degrees as they do at 30 to 32 degrees.
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UPDATE 5:45PM: For the first time since the Noon hour, visibility at Chicago's O'Hare International Airport has improved to 1 mile at 5:40PM. Snow is expected to continue to fall in the Chicago area through 9PM, but it appears that the heaviest snow is starting to shift east of the Illinois.
The latest snowfall totals include:
6.5" Chicago Ridge
5.9" Chicago- Midway
5.5" Westmont
5.3" Oak Lawn
5.0" Schererville, IN
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UPDATE 5:00PM Snow is starting to let up in western Illinois with visibility improving to around 1 mile. Here in Chicago, moderate to heavy snow will continue for another hour or two before the storm begins the process of winding down.
Here are a few of the more recent snowfall totals that have come in to the WGN Weather Center at 5PM.
6.3" Galena, IL
5.5" Lincolnwood
5.3" Geneva
5.2" Chicago-Midway
5.0" Lake Zurich
4.7" Bolingbrook
3.5" Valparaiso, IN
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UPDATE 4:25PM:
RIGHT: Streets of Oak Lawn are quiet as heavy snow falls at 4:20PM.
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UPDATE: 3:55PM Snow intensity is expected to taper somewhat after 6PM to 7PM tonight. Until then, moderate to heavy snow will continue to fall across most of the Chicago area. The snow has slowed highway and road travel to a crawl, and the CTA has pulled all buses off Lake Shore Drive. Train travel appears to be the best way to get around in the short term. Here are a few of the latest snowfall reports from across the area:
4.5" Yorkville
4.0" Bolingbrook
3.4" Carol Stream
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UPDATE 2:55PM: The timing and intensity of today's snowstorm is making for a nightmarish commute across the Chicago area. Long distance travel is not recommended. At 3PM, WGN720 radio is reporting three hour travel times on the Eisenhower and Stevenson Expressway between downtown and the far western, southwestern suburbs.
3.5" De Kalb
2.8" Geneva
2.5" Chicago- Loop/Streeterville
ABOVE: Not much wind, but plenty of snow in Sauk Village.
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UPDATE 2:05PM: Moderate to heavy snow continues to fall across most of the Chicago area at this hour. Here are a few of the snowfall totals that have been reported to us in the WGN Weather Center.
8.0" Ringsted, IA
5.0" Dubuque, IA
2.5" Elburn, IL
2.5" Rockford, IL
2.3" Joliet, IL
2.0" Bolingbrook, IL
1.9" Batavia, IL
1.9" Chicago- Hyde Park
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UPDATE 1:05PM: Chicago will be in the heart of this snowstorm for the next 4 to 5 hours with moderate to heavy snow falling at a rate of at least one inch per hour. At 1PM, heavy snow (visibility 1/4 of a mile or less) is being reported at O'Hare, Midway, West Chicago and Wheeling.
RIGHT: Visibility reports at 1PM
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UPDATE 12:45PM: Heavy snow is being reported in Aurora and Elmhurst at 12:45PM. Here are a few of the latest snowfall totals
7.0" Waterloo, IA
1.5" Byron, IL
1.3" Winnebago, IL
1.0" Schaumburg, IL
0.7" Schererville, IN
5 to 8 inches of snow is likely across much of the Chicago area by Saturday morning. Locally heavier totals of 9 to 10 inches are possible in a narrow 5-10 mile wide band. Most of that accumulation will fall between now and 8PM.
ABOVE: Snow on Chicago's south side near Miles Davis Academy
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UPDATE 12:15PM: Snow intensity continues to increase at this hour. Visibility at the Aurora airport in Sugar Grove is down to 1/4 of a mile.
Here are a few snowfall totals as of Noon:
2.0" Peru, IL
1.5" Amboy, IL
1.0" Ottawa, IL
1.0" Elburn, IL
1.0" De Kalb, IL
0.5" Rolling Meadows, IL
0.5" Yorkville, IL
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UPDATE 11:15AM: It's getting a little nasty in Iowa. So bad, the National Weather Service just upgraded a large chunck of eastern Iowa from a Winter Weather Advisory to a Winter Storm Warning. 3" on the ground in Dubuque and Cedar Rapids so far.
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UPDATE 11:05AM: Snow is really starting to pick up over northern Illinois. Visibility at O'Hare Field dropped from 10 miles to 1/2 mile between 10Am and 11AM.
RIGHT: The view from our tower cam in De Kalb, Illinois where visibility is reduced to 1/2 mile due to moderate snow.
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10:50AM: Not all 5 to 8 inch snowstorms are the equal. (reposted from yesterday)
Sometimes snowstorms are all about timing. Several factors are coming together to produce what looks to be a medium to high impact snowstorm for Chicago area commuters. A few of these factors are:
1) The majority of the snow will fall during the day.
2) The heaviest snow is expected during the afternoon and evening.
3) It's a weekday.
4) It's a Friday.
5) Cold temperatures- Road crews will be challenged by temperatures well below freezing, in the teens to around 20 degrees. Chemicals used to melt snow and ice don't work as well, or as quickly as they do at 30 to 32 degrees.
The bottom line- all 4 to 8 inch snowstorms are not equal. Chicago snowstorms that hit at night, or on the weekend, tend to have a much lower impact on travel.
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UPDATE 10:20AM: Snow is quickly intensifying over the Chicago area from west to east at 10:20AM. Visibility has dropped below 2 miles in Aurora, De Kalb, Rockford and Morris. Further west, heavy snow (visibility of 1/4 of a mile or less) is being reported in Moline, Dubuque, Waterloo and LaCrosse.
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UPDATE:9:45AM: Snow continues to quickly spread across northern Illinois from Iowa and Minnesota. At 9:30AM, a very fine light snow is being reported in some of Chicago's western suburbs including St. Charles. Elsewhere, a small plume of what appears to be lake effect snow has developed over the city. Lake effect snow is being reported in the Loop and at Midway Airport.
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9:00AM: A Winter Storm Warning continues for most of the Chicago area north of I-80 through Midnight. A Winter Weather Advisory continues for areas along and south of I-80 until Midnight.
WHAT, HOW MUCH: 5 to 8 inches of snow is likely across much of the Chicago area by Saturday morning. Locally heavier totals of 9 to 10 inches are possible in a narrow 5-10 mile wide band.
WHO, WHERE: Locally, the Winter Storm Warning includes includes Cook, Lake(IL), Winnebago, McHenry, Kane, De Kalb and Du Page Counties.
The Winter Weather Advisory includes Kendall, Grundy, Will, Kankakee, Lake(IN), Porter(IN), LaPorte(IN), Berrien(MI), Kenosha(WI) and Walworth counties.
WHEN: Snow will begin between 9AM and 11AM, lasting most of the day and into the evening before tapering to flurries late Friday night. The heaviest snow is expected to fall between 1Pm and 5PM. Due to the fact a majority of the snow will be falling on a weekday, and during daylight hours, this is expected to be a high impact storm for commuters.
As low pressure spreads snow from the central plains east into the Midwest this morning, the National Weather Service has issued a combination of Winter Storm Warnings and Winter Weather Advisories for the next 24 to 36 hours extending from extreme southeastern South Dakota through southern Minnesota, much of Iowa, southern and northern Wisconsin, northern Illinois, southern Lower Michigan, northern and central Indiana, and all of Ohio, Pennsylvania into New Jersey. Snowfall amounts will range from 3 to 8 inches along this west-east path as a low pressure system tracks out of the central plains east up the Ohio Valley Friday into Saturday. Where temperatures are closer to 32 degrees, portions of Ohio and Pennsylvania will experience a mix of freezing rain and sleet along with eventual snow accumulation.
In the Chicago area including southeast Wisconsin and northwest Indiana anywhere from 3 to 8 inches of snow could occur with Chicago itself positioned to possibly be hit with greatest amounts in the 5 to 8-inch range due to the initial storm surge into this evening - followed by a northeast wind on the backside of the low pressure system as it moves to the east possibly creating lake effect snow along the Illinois Lake Michigan shoreline later tonight into Saturday.
WINTER STORM WARNING FOR THE FOLLOWING COUNTIES
WINNEBAGO-BOONE-OGLE-DE KALB-MCHENRY-LAKE-KANE-DUPAGE-COOK
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...OREGON...DEKALB...WAUKEGAN...WOODSTOCK...AURORA AND WHEATON AND CHICAGO
A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 9 PM CST THIS
EVENING.
* TIMING...SNOW WILL DEVELOP DURING THE EARLY TO MID MORNING HOURS IN WESTERN PORTIONS AND CONTINUE THROUGH THIS AFTERNOON...ENDING THIS EVENING. THE HEAVIEST SNOWFALL WILL OCCUR DURING THE LATE MORNING INTO THE MID AFTERNOON.
* ACCUMULATIONS...SNOWFALL TOTALS OF 5 TO 8 INCHES CAN BE
EXPECTED.
* HAZARDS...SNOW WILL FALL HEAVILY AT TIMES RESULTING IN REDUCED
VISIBILITIES AND SNOWFALL RATES OF AROUND ONE INCH PER HOUR AT
TIMES.
* IMPACTS...ACCUMULATING SNOW WILL CAUSE SIGNIFICANTLY INCREASED
TRAVEL TIMES...RESULTING IN A PARTICULARLY TREACHEROUS AFTERNOON
COMMUTE. IN ADDITION...VERY COLD TEMPERATURES IN THE TEENS WILL
MAKE SALT LESS EFFECTIVE AND COMBINE WITH HEAVY SNOWFALL RATES
TO MAKE IT HARDER FOR ROAD CREWS TO KEEP ROADS CLEAR OF SNOW AND
ICE. THE SNOW WILL ALSO RESULT IN SIGNIFICANT DISRUPTIONS TO AIR
TRAVEL AS WELL.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A WINTER STORM WARNING FOR HEAVY SNOW MEANS SEVERE WINTER WEATHER
CONDITIONS ARE EXPECTED OR OCCURRING. SIGNIFICANT AMOUNTS OF SNOW
ARE FORECAST THAT WILL MAKE TRAVEL DANGEROUS. ONLY TRAVEL IN AN
EMERGENCY. IF YOU MUST TRAVEL...KEEP AN EXTRA FLASHLIGHT...
FOOD...AND WATER IN YOUR VEHICLE IN CASE OF AN EMERGENCY.
by Mike Hamernik twitter @Mike Hamernik
RIGHT: Winter Storm Warning Friday and Friday night for 4" to 8" of snow. Most of the snow will fall between 10AM and 7PM. 
UPDATE: 9:29PM: The National Weather Service has replaced Friday's Winter Weather Advisory with a Winter Storm Warning. The warning means there is the potential for 6 inches or more of snow.
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4:30PM: A Winter Weather Advisory has been issued by the National Weather Service effective Friday and Friday night for most of the Chicago area.
WHAT, HOW MUCH: This advisory replaces the Winter Storm Watch issued yesterday. Despite the change in "headlines" from the National Weather Service, there is little change to the going forecast of 4 to 8 inches of snow by Saturday morning, with locally heavier totals of 9 inches possible in a narrow 5-10 mile wide band.
South of the advisory area, 1" to 3" of snow is expected at this point. Check back with us throughout the night and during the storm tomorrow, as storm totals will need to be adjusted if the system deviates from it's expected track.
WHO, WHERE: Locally, the advisory includes Cook, Lake(IL), McHenry, Kane, De Kalb, Du Page, Kendall, Will, Lake(IN), Porter(IN), LaPorte(IN), Berrien(MI), Kenosha(WI) and Walworth(WI) counties.
WHEN: Snow is expected to move in to northeast Illinois between 7AM and 10AM Friday, lasting most of the day and into the evening before tapering to flurries Friday night. Due to the fact the majority of the snow will be falling on a weekday, and during daylight hours, this is expected to be a high impact storm for commuters.
WHY: Because it's January in Chicago.
BELOW: Winter Weather Advisories extend beyond Chicago into Indiana, Michigan, Wisconsin and Iowa.
by Mike Hamernik twitter @Mike Hamernik
UPDATE 10:00AM: Bursts of heavy lake effect snow have prompted the National Weather Service to extend a Winter Storm Warning for LaPorte, St. Joseph and Berrien counties
until 7AM EST Saturday. Two to seven inches of new snow is likely north of highway 6.
RIGHT: The heaviest lake effect snow is expected to fall from northern Berrien county to South Haven, Michigan. In Indiana, the northern portions of Porter, LaPorte and Berrien counties can expect to see the most substantial (1"- 4") accumulation.
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UPDATE 9:05AM: As yesterday's storm moves east, the National Weather service is allowing most of the area's advisories and warnings expire.
The Winter Storm Warning for Lake and Porter Counties expired at 9:00AM.
The Winter Weather Advisory for Benton, Jasper and Newton Counties expired at 9:00AM.
Winter Storm Warnings continue for the Michiana snowbelt counties of La Porte, Berrien and St. Joseph until 7AM EST Saturday
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7:25AM: All winter weather advisories and warning have been canceled for Chicago and northern Illinois.
Winter Storm Warnings remain in effect for Lake (IN) and Porter counties until 9AM.
Winter Storm Warnings continue for the Michiana snowbelt counties of La Porte, Berrien and St. Joseph until 7PM EST today.
A Winter Weather Advisory continues for Benton, Jasper and Newton counties until 9AM CST.
