A potential blizzard may dump 6 inches of snow or more starting Friday, much of it heavy and wet, similar to the “heart attack snowstorm” of 1987 when two dozen people died mostly from the stress of shoveling.
Unlike the tepid snowfall earlier this week that mostly melted, colder temperatures will keep the snow sticking, and gusts up to 50 mph may turn the storm into a blizzard Friday night, according to the National Weather Service. A brutal, lengthy cold snap will follow.
The storm will pose “life-threatening travel conditions,” the weather service warned.
“It’s not going to be a nice Friday morning and evening commute,” said Jake Petr, a meteorologist with the weather service in Romeoville.
The storm will have several distinct phases.
Friday morning’s “initial thump of snow” — between 2 and 4 inches starting at 6 a.m. — will turn to rain in the late morning and early afternoon, Petr said. That will be followed by lighter, fluffier snow in the evening as temperatures drop and wind gusts rise to 50 mph.
The snow may briefly stop Friday evening, but the wind may whip up what’s already fallen and cut visibility, he said. Snow totals will be lower along the lakefront and higher in the northwest suburbs, Petr said.
Forecasters are debating if those high winds Friday night will technically result in a blizzard. That would require sustained 35 mph winds and visibility of under a quarter mile for at least three hours, Petr said. The current forecast calls for a 30% chance of that.
The National Weather Service’s forecast says the storm “bears a striking similarity to the heart attack snowstorm of Dec 15, 1987,” which dropped a foot of snow and produced lightning.
Friday’s storm will also feature heavy, wet snow, Petr said. There could even be some lightning in a “narrow band” of the storm, he said.
“Travel is discouraged,” Petr said. “But if you have to, it’s worth making preparations,” he said, such as booking alternative housing or brining a car kit with a blanket and food.
Cold snap
An extreme cold front pushes into the area later Saturday and will linger for days. The sudden drop in temperatures could result in a flash freeze on untreated surfaces, according to the weather service.
But Chicago likely won’t break any cold records. Daily highs will remain in the single digits from Sunday through Wednesday, with lows dipping into the negative single digits.
Wind chills will remain minus 10 degrees or below from Saturday night through Wednesday morning, Petr said. The coldest wind chills of minus 20 and 30 are expected Sunday night into Monday.
Temperatures will likely rise back into the teens and 20s on Wednesday and Thursday, he said.
The length of the sustained cold is similar to the cold snap of 2017-2018, when Chicago remained below 20 degrees for an 11-day stretch, Petr said.
Forecasters are hesitating to call this a polar vortex because there are several factors that go into that, Petr said. They are instead calling this a “longer duration cold snap.”
A winter storm watch is in effect from 6 a.m. Friday through 12 p.m. Saturday, according to the National Weather Service.