How the probability score is built
Eight factors go into the score, and each one is weighted by how much it actually tends to influence a real closure decision. Snowfall and ice carry the most weight because they're the biggest safety factors for buses and walking students; location, timing, and school history contribute smaller adjustments on top.
| Factor | Weight |
|---|---|
| Snowfall amount | 25% |
| Ice accumulation | 15% |
| Temperature | 15% |
| Wind speed | 10% |
| Snow timing | 10% |
| Road conditions | 10% |
| School's closure history | 10% |
| Location type | 5% |
Each factor is scored on its own 0-100 scale first — for example, 6 inches of forecast snow scores much higher than 1 inch — and those scores are then multiplied by their weight and added together to produce the final percentage.
Why snow and ice aren't scored the same way
Snow and ice behave completely differently on roads, which is why they're tracked as separate inputs rather than lumped into one number. Snow, especially in smaller amounts, can usually be plowed and salted ahead of a morning commute. Ice is a different problem: it bonds directly to pavement, resists most treatment, and stays dangerously slick well after the storm has passed. That's why the model's ice score climbs steeply even at accumulations of a quarter inch or less — a thin ice glaze is often treated as more disruptive than several inches of dry snow.
Why timing and location shift the same storm's impact
Identical snowfall totals can mean very different things depending on when they arrive and where. Snow that falls overnight and stops before the morning bus run is far less disruptive than the same amount still falling during the commute, which is why timing is its own input. Location works the same way — a well-plowed urban district with short bus routes can often function through conditions that would strand rural buses on unpaved or hilly roads, and a school's own history of caution (or lack of it) tends to repeat itself storm after storm.
What this number is, and isn't
This is a weighted estimate built from general weather-safety patterns, not a feed from any school district's actual decision process. Superintendents weigh live road reports, bus fleet realities, and local policy that no public formula can see, and they often make the final call in the early morning hours as conditions actually develop — well after any forecast-based estimate was calculated. Treat a high probability as a reasonable heads-up to keep an eye on your district's official channels, not as the final word — always confirm with the school's own website, app, or local news before making plans around it.
Related weather calculations
Wind chill is one of the factors that makes cold-weather mornings feel more dangerous than the thermometer alone suggests — the wind chill calculator works out how cold a given temperature and wind speed actually feel.