Monday, February 03, 2014

Snow Day Analysis

Debates about whether or not schools should be closed for snow, cold, or whatever can get pretty heated. On one side, you have the "They're closing school for THIS?!?!?" crowd. On the other side, you have the "How DARE you put our children in danger!!!!" crowd. There's usually a lot of yelling.

Well, no yelling here. No debating the appropriate threshold should be for school closures in Central North Carolina. Instead, I'm just going to try to figure out what that threshold is, so that I can reasonably predict well in advance (i.e. before I go to bed the night before) whether my daughter's day care - and when she gets older, her school - will be closed for inclement weather. What does it take to close or delay schools around here?

This winter, I've been paying more attention to this sort of thing. I'm primarily tracking three institutions: Wake County schools, Durham schools, and my daughter's day care. After a pretty uneventful December, all three had several days, and some closures, in January. Let's analyze each one, because they all provide some useful data points:

January 7, 2014: the "polar vortex" cold outbreak*
(* - This is not an endorsement of using the term "polar vortex" as the name for this or any other cold snap.)

No snow, but it got cold: lows in the single digits, wind chills below zero, both the lowest seen here since the 1990s. Everybody freaked out, and so, Wake, Durham, and our day care all delayed by two hours.

That begs the question: does a Wind Chill Advisory result in a school delay? (In Central NC, a Wind Chill Advisory is issued for below zero wind chills.) I thought so, but then on January 24, another Wind Chill Advisory was issued. But did Wake/Durham/day care post a delay? Nope; they all opened on time.

I think the moral of the story is that perhaps the first Wind Chill Advisory of the season is enough to prompt a delay, at least if there's enough media hysteria surrounding it. Any Wind Chill Advisories after that, no big deal, I guess? Again, I'm not here to debate what the appropriate threshold should be; I'm just trying to figure out what that threshold is. Calls to the Wake County Public Schools were not returned.

January 21-22, 2014: Light snow, mostly east

A Winter Weather Advisory was issued for an expected inch or two of snow, mostly accumulating on elevated/grassy surfaces and not on the roads (too warm), starting Tuesday at 4:00 PM. That was not enough to force schools to close early, but it did cancel after school activities. The next morning, after less than an inch fell across the Triangle (more so in eastern Wake County than anywhere else), Wake, Durham, and our day care posted a two hour delay.

I think any measurable overnight snow that produced at least some accumulation will always lead to at least a delay, even if it melts quickly.

January 28-31, 2014: Snow, for real this time!

Here's the big one. The Winter Storm Warning went into effect at Tuesday 12:00 PM, expecting 1-5" (depending on where you live) through Wednesday morning. Wake County closed completely on Tuesday; Durham closed three hours early; our day care closed two hours early. As it turns out, snow didn't arrive until after sunset, but given that the NWS Advisory went into effect at noon - and given what happened in Atlanta - everyone will generally err on the side of caution in situations like this. Some more than others, I guess you could say.

Everyone in the Triangle got at least an inch of snow; people in eastern Wake County got close to 4". And with temperatures staying below freezing on Wednesday, everything was closed.

Now, for those who don't know how it works here: after it snows here, they plow the main roads, and then eventually they might get around to all of the secondary roads, maybe. Because of those pesky secondary roads, schools generally won't reopen until the snow on those roads melts naturally. Wake County is a pretty big county, so if there are still ice-covered roads somewhere in the county, their entire school system stays closed.

With that said, Wake County kept schools closed Thursday and Friday, making for four consecutive snow days. (All of which they'll have to make up, by the way.) Durham re-opened Friday, albeit with a three hour delay. Our day care reopened Thursday morning on a one hour delay.

My takeaways from this are:
- Schools stay closed until ice-covered secondary roads clear up on their own, because NC DOT doesn't have time or resources to get around to all of them. How long that takes depends as much on how warm it gets after the snow hits, as it does how much snow we get. So, a January snow event would, in theory, keep schools closed longer than the same snow event would in March.
- Our day care stays open more than the public schools do, which is nice for us. (For the time being.) I used to think they just followed the lead of Durham Public Schools, but, nope.

That's what we've learned so far. Until the next winter weather event!


bubba0077 said...

A map was making the round on social media a few days ago from a reddit thread where they crowdsourced how much snow it takes to close school around the country:

That said, your observation about taking more to close school a second time for wind chill likely has some merit behind it. While laws in other states are likely different, I know in NJ you had to be in session for 180 days to be considered a complete school year, so days off mean either extending the school year or cutting other planned days off. However, as these accumulate it becomes harder and harder to accommodate the make-up days needed. So, the cost of cancelling one day of school can be pretty low, but as days mount (particularly when it is still only mid-winter) it becomes a bigger and bigger deal.

bubba0077 said...

In particular, there was one year I recall in NJ (I believe it was 93-94) where they were nervous about being able to get enough days in. NJ had (has?) a law saying school couldn't be held past the last day of June, and NJ already goes several weeks into June normally. Repeated heavy ice storms resulted in at least a dozen closed days and trimmed just about all of the remaining holidays off the calendar and it was getting close to the point where there wasn't any room to add more days without going into July.