Snow day predictor

Why the same storm closes one town and not the next

Most snow day calculators score every location against the same number. That gets the biggest thing wrong: a district’s plough fleet, bus fleet and driver expectations are all sized to a normal winter, so the amount of snow that closes school depends on how much snow the place normally gets. Six inches is an ordinary Tuesday in Syracuse and a shutdown in Atlanta.

So every location here is scored against its own NOAA 1991-2020 average annual snowfall, measured at the nearest reporting station:

• Snow belt100 in and up a yearcloses at roughly 12 in in one event
• Heavy snow60-100 in a yearcloses at roughly 8 in in one event
• Regular snow35-60 in a yearcloses at roughly 6 in in one event
• Moderate snow18-35 in a yearcloses at roughly 4 in in one event
• Occasional snow6-18 in a yearcloses at roughly 2 in in one event
• Rare snow1-6 in a yearcloses at roughly 1 in in one event
• Essentially snowless0-1 in a yearcloses at roughly 0.5 in in one event

The snowfall figures are measured. The thresholds are our assumption, published here so you can argue with them rather than guess at them. Ice is weighted well above its depth - a tenth of an inch of freezing rain strands buses that eight inches of powder would not - and wind and dangerous cold each add on their own. Weekends score zero.

This is a model, not an announcement. Nobody here knows what your district will decide.