**A Winter Storm Warning is in effect for Chicago Tuesday 3am CST to midnight CST**
The likelihood of widespread and potentially significant snowfall is increasing as the second winter storm in a week has its eyes set on Chicago. The main uncertainty at this time is the placement of the axis for heaviest snowfall (6-8"+).
Storm Timing: Monday night through Tuesday.
Note: An inch of snow is possible during the day on Monday ahead of the main storm. Details below.
Heaviest snow timing: From 6am Tuesday through 6pm Tuesday night.
Snow amount probabilities:
- Snow of 1" or more: 90% (high)
- Snow of 4" of more: 75% (high)
- Snow of 6" or more: 55% (moderate)
- Snow of 10" or more: 35% (low to moderate)
- Snow of 12" or more: 10% (low)
Of 6 forecast models, two (the UKMET and the GEM) are suggesting a storm track that will put heaviest snowfall over southern Wisconsin, two (NAM and SREF) are favoring a track of heaviest snow downstate (central IL)southwest of the area, and two (Euro and GFS) are suggesting a track in between (over northern Illinois/NW Indiana). Below is a look at the possible scenarios that could take place and what impacts they could cause.
Scenario #1 High Impact/Probability: 40%
The storm tracks farthest north putting the axis for heaviest snow (6-12") over southern Wisconsin. A track such as this will bring a swath of 3-8 inches over the Chicago area (heaviest north). This will still result in high impacts such as traffic delays (both air & ground) and possible power outages due to downed power lines from the heavy snow.
Scenario #2 High Impact/Probability: 40%
The storm tracks across central IL putting the axis of heaviest snowfall (6-12") over northern IL/NW Indiana including Chicago. This would be the worst case scenario for Chicago causing major delays, cancellations, and potential power outages.
Scenario #3 Medium Impact/Probability: 20%
The storm tracks over southern Illinois putting the heaviest axis of snowfall (6-12) over central IL and areas southwest of Chicago. Snow amounts ranging from 3-8" would be possible with the heaviest amounts occurring south of Interstate 80. This would result in moderate impacts over the greater Chicagoland area.
(Note: Snow amounts and probabilities are preliminary estimates and are subject to change based on the exact track of the storm).
An upper level low will travel across Montana (tonight) southeast into the Northern Plains (Monday) and into the Midwest region (Monday night). Meanwhile, a surface low will develop across the central Plains and travel in conjunction with the upper level low into the Midwest eastward towards the Ohio Valley on Monday. Strong forcing from a powerful NW jet aloft along a baroclinic zone and ample moisture feed from the Gulf of Mexico will result in a formidable winter storm from the northern Plains southeast to northern Illinois and northwest Indiana. Winter Storm Watches/Warnings have been hoisted from the Dakotas (tonight through Monday) southeast through Chicago (late Monday through Tuesday evening). It is worth noting that snow will fall over parts of the Chicago area during the day on Monday ahead of the main storm. An inch of snow is not out of the question on Monday.
Bottom Line: Regardless of scenario, everyone should be aware and prepare accordingly for some snow and potential impacts Monday through Tuesday night. Stay tuned for more updates!
Prepared by Meteorologist Andrei Evbuoma on
Saturday, March 3, 2013 at 5:00 P.M. CST
Copyright © 2013 by Andrei Evbuoma
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