How much snow it takes to cancel school


The pointer is from Ángel Cabrera, link here.


I bet if you made a map of "number of snow plows per capita" it would look similar.

I suppose we need a federal snow plow reserve.

I'd say "snow plows + Salt trucks per capita", but otherwise you are probably correct.

Can't one vehicle do both?

Sure, but it's not always the case.

You forgot cars with snow tires and tire chains.


Think they should do another one showing how often school gets closed for snow on Fridays or Mondays as opposed to Tues, Wed, Thurs.

Or how the amount of snow needed to cause a closing changes as we get towards the end of winter and there might be unused snow days left in the time budget.

They aren't even filtering for "never get closed, never get snow." Beyond "'any snow" they need "no worries." (He said from the Southern Californian coast, altitude 45 feet.)

I'm somewhat surprised that Illinois has the same variation as California. I grew up in suburban Chicago...we used to think southern Illinois was the "deep south" and I guess in terms of snow, it is!

Certainly by any sort of size/latitude adjustment, Illinois wins for volatility.

I spent some years in southern Illinois, and it's definitely the south; in culture, climate, and snow response. A forecast of an inch of snow would send everyone scrambling to the store to buy every last loaf of bread and gallon of milk.

Yeah, what's with the panic over not being able to buy milk? Would your teenage daughter go into a coma without a glass of milk for lunch? For even a day or two? How about a four year old? If a four year old never go another glass of milk would he expire before five? Or would his teeth just fall out?

Around New Ulm, Minnesota, when a big blizzard is immanent, nobody worries about milk, they stock up on sausage.

Well, milk or some other store-able carb, the coma thing, when she was four.
Sorry, couldn't help myself!

I too am surprised by Illinois. I'm not surprised by Chicago, but the map makes central and southern Illinois look whimpy. There aren't a lot of metro areas down there, though: Champaign-Urbana, Danville, Bloomington-Normal, Springfield, Quad Cities. I thought the counties were well equipped for snow removal, and I know that I-57 and I-55 get cleared quickly.

I suppose this vindicates Obama's "flinty Chicago toughness" comment.

We Chicagoans took a hit to our perceived toughness this week. They cancelled school 2 days with basically no snow; just due to cold. I heard that this was the first multi day closing without 20+ inches of snow in 25 years. Also heard, but haven't verified, that the rules were tweaked this year to add a few reserve days that don't have to be made up at the end of the year-- "use 'em or lose 'em" for the teachers. Whether the days have to be made up is the driving force behind how many snow days there are.

Given that Chicago never gets 24" of snow in a single storm, I'm going to point out that that's a silly map.

In the 2011 storm Midway Airport recorded 22" with blizzard winds. That not good enough for ya?

No. And 12+ inches of snow is about once a decade event here, yet we still have school closings because of snow.

Hailing from downstate Illinois, the "snow" days don't necessarily have any snow. Its the double digit below zero wind chill that has been cancelling school this year. I wouldn't just look at snow removal equipment, but amount of bussing.

@Careless, the thing about pedantry is that it can come back at ya. Chicago's had two 12"+ snow events just in the last three years.

5 in the last 35 years, 8 in the last 70. Once every 10 years wasn't bad for a top of the head estimate.

And I wasn't being pedantic. School in Chicago closes because of snow. Chicago never gets 24" of snow. That map is ridiculous, at least in my corner of the country.

10" might be an accurate threshold.

That's an estimate of 10" for the blue area on the map around Chicago, not the city itself which probably takes more snow to close.

I guess data binning is only a problem when someone else does it.

The color on that map is so awful that I find it difficult to force myself to try to read it.

blue-green colorblind?

Here's a much bigger version.

Closer look at the map, I kind of wonder.

We're in a 24 inch zone. We don't get 24 inches here.

When we get school closings, it's not usually because of volume of snow, it's the conditions. E.g., did it snow and stop so that the plows can clear the roads, or does it snow all day and night? Is there wind, blowing snow? Is there a wet snow and then very cold temps, which freezes windshields over? Did we have a previous snow, then a warm burst or salting the roads so much melted, then a 6 degree day so everyone's driving on a sheet of ice?

Fun map, but don't know it really says much.

Information on how it was created:

Clarifications there make me feel warm and fuzzy towards it -- he's not trying to be definitive about anything, just throw out some interesting stuff with caveats. I can get behind that. Also, funny.

You are quite correct that inches of snow is a flawed measure, but I doubt that there would be better data. If inches of snow is highly correlated with the conditions you describe, then the map would be accurate except perhaps on the borders of the isowhimps.

We got about 1/4 inch of sleety-ish ice, and school was closed that day, the next day, and the day after the next day (just to be safe). Model that one.

I grew up in a dark blue county. Not once did we ever cancel school for any weather reason. I live in a green county now and the difference is very stark. They just got three inches of snow and didn't just cancel school, they cancelled life. Most businesses didn't open. My neighbors acted like I was insane for driving. The plow trucks basically just drove back and forth on the main roads, even though they'd been cleared. It was like they were just waiting for more snow.

In the winter of 1977-78, we went on Christmas break around December 20th, and didn't return to school until February 15th because of snow. Lived in one of the green/blue areas.

Maybe the plows were afraid to drive on the unplowed streets

"I grew up in a dark blue county. ... My neighbors acted like I was insane for driving. "

In my area, middle TN, it's almost comically common to have a Yankee transplant confidently proclaim that the locals just don't know how to drive in snowy weather. And then end up getting stuck in a ditch on the side of the road because the "snow" in this area is often mostly ice and it's far more hilly here than it was at home. We have a lot of Michigan-born engineers in the area.

Also, I don't believe that Seattle, or King county is anything but a green county. They once cancelled school because of excessive rain.

Excessive rain can flood drainage systems which clogs roads. Was it really just because the rain was too heavy? I have been in rainstorms here in Illinois when winshield wipers could't clear the windshield fast enough. I'd say that is a legitimate school closing event.

You raise a good point that states like Florida may cancel school for other weather-related events such as hurricanes.

I think there is also a feedback effect: if a heavy snow area canceled school every time they had a foot of snow, school would extend deep into the summer for lengths varying by year. In other words, the costs of canceling are higher.

I twice saw water coming UP out of strom sewers in Urbana.

Schools in Florida cancel on hurricanes because the schools also function as shelters. Unlike snow days school will be cancelled several days in advance on the forecast of a possible hurricane, and even if the hurricane doesn't hit school will remain closed.

Seattle's threshold seems to be "50% or greater chance of at least one snowflake falling somewhere in the district during the day" and/or "more than 25% of the snow from the previous storm is still on the ground". We're still making up for the storm in 1990 that forced a bunch of students to spend the night at school.

What about number of days of closing per inch of snow? For example, where I live there were about 4 inches of snow on Tuesday, and school has been closed for 3 days. That has to vary nationwide well.

The St. Louis data is a crock. I have never seen cancellations for one inch. Ever. Perhaps one inch on top of ice. Ice followed by a small amount of snow is the normal winter weather in the lower Midwest and middle south. By and large the north doesn't experience it. Example of asking the wrong question because of ignorance of the topic.

Agree. I grew up in St. Louis, and I recall going to school many times in 3-4 inches. It took 6 inches before school was closed.

Living btw/ Chicago and St. Louis, one realizes that a lot of the bad winter weather ("the mix") goes to the south of us, and you hope for a nice heavy dry snow.

This map isn't great. I grew up in a darkest blue county and we cancelled plenty of times with less than 8". How often do you get 24" of snow in a day, anyway?

The real issue was timing and type of snow, because cancellations depended on whether the buses could drive safely (and whether the plows had time to clear the roads). 6 inches of powdery snow at 9 PM would usually not result in a snowday. 2 inches of icy slush at 5 AM might do the trick, however.

The fun part was deciding whether or not you had to do your homework for the next day based on the weather reports.

Some of what you describe might explain the high snow threshholds in cold-hardened regions. For example, in the mid atlantic, a little snow and freezing rain can make driving unsafe, but in, say, Vermont, I imagine freezing rain isn't a common issue in the winter.

It's fascinating how much "news" these days comes from non-reddit internet pages recycling information that started as freely user generated content on reddit.

Joshua, you are on a blog.

I live in the heart of the green (austin, tx). Anyone living here knows we usually get ice, not snow. Having spent plenty of time in NYC and CHI, I always chuckle when someone tries to compare the two. There's also the hazard of having to share roads with people who don't understand the difference.

11 nations of America

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