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    App predicts likelihood of school snow days

    David L. Ryan/Globe Staff/file 2011
    Ken Reeves, senior meteorologist at the weather data service, has doubts about the app’s ability to predict snow days.

    With snow predicted for later today, will schools close tomorrow?

    A new app reportedly predicts whether a storm will shutter your school even before the principal knows.

    The app, called sNOw School, combines live weather data with information on past closings from individual schools and school districts to calculate the odds of a snow day.


    Ben Zeidler, one of the app’s developers, said that the inspiration was his own childhood in Philadelphia. “I remember always wanting a snow day, but never knowing if it would happen,’’ he said.

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    But Matthew F. Wilder, spokesman for Boston public schools, is a skeptic, doubting the app’s ability to accurately predict the city’s snow cancellations.

    “We welcome any technology that helps us communicate with students and family,’’ Wilder said. “But every storm is different, and ultimately, it always comes down to a human decision.’’

    In Boston, officials usually make the decision to call a snow day the evening before, then contact local media and post cancellations on Facebook, Twitter, and the district’s website. When there’s a cancellation, an automated phone system calls families with children in the city’s schools.

    The brainchild of three recent Georgetown University graduates, sNOw School was launched in five cities, including Boston, on Feb. 1. Since there hasn’t been much snow, the storm predicted for later today could be its first real test here.


    The app costs 99 cents, and is available for’s Kindle e-readers and tablets, devices running Google Inc.’s Android operating system, and Apple Inc.’s iPhone, iPod Touch, and iPad tablet. The developers declined to release sales numbers, but said that “hundreds’’ have been sold in the month since it was released.

    Zeidler, 25, said that before the era of cellphones and social media, he didn’t know whether he had gotten a snow day until his parents opened his bedroom door to tell him the good news.

    “The anticipation of snow days was always fun,’’ he recalled. “The superstition was that if you wore your pajamas inside out, it would help the odds.’’

    Zeidler and two friends began creating the app two years ago by collecting closing data on more than 5,000 schools in Boston, the New York metro area, Philadelphia, Baltimore, and Washington, D.C. The app compares the current day’s forecast to the weather that prompted past closings, and calculates the odds for whether a coming storm will be bad enough for authorities to call a snow day. Three feet of snow on the way? Judging by past history, break out the sleds and skates and plan to sleep late.

    To add a layer of fantasy, sNOw School lets the user alter the data (inches of snow and duration of snowfall) and see how it affects the prediction. Let’s say there are 3 inches of snow instead of the 3 feet in the forecast.


    The odds of a cancellation drop proportionately.

    ‘It always comes down to a human decision.’

    Matthew F. Wilder Boston public schools

    Although there are a handful of other snow day-type apps available that calculate the likelihood of cancellations based on the projected snowfall for a ZIP code, sNOw Day is the only one, Zeidler said, that uses past data from individual schools to fine-tune its predictions.

    Like Wilder, Ken Reeves, senior meteorologist at the Pennsylvania-based weather data service, said there are “too many variables involved in a snow closing’’ for an app like sNOw School to reliably deliver accurate predictions.

    “There are many convoluted, almost political considerations that often play a role in a school closing,’’ he said. “Was the previous snow closing premature? Or too late? Is it the third 5-inch snowfall of the month? Those factors play a role, and they aren’t constant.’’

    Reeves’s advice: “Sounds like a fun app, but I would advise students not to skip their homework based on it.’’

    The Boston area may be a particularly tricky call for the app. Zeidler said it’s the “stingiest’’ of the five regions the developers tracked in terms of granting snow days.

    “Boston gets more snow than Washington, D.C., but they have fewer snow days,’’ he said.

    Zeidler said that of Boston-area schools, Harvard University is the least likely to cancel classes; the Massachusetts Institute of Technology and Babson College in Wellesley are nearly as reluctant to call a snow day.

    On the other side of the equation, local art schools like the School of the Museum of Fine Arts and religious schools are easier, according to the app developer. “It seems that schools that start with ‘Saint’ are a little bit more inclined to declare snow days,’’ Zeidler said.

    William Marks, a Harvard senior who purchased the app earlier this month, is looking forward to using it to track his snow day odds as the storm approaches.

    “Even though we haven’t had much snow this year and snow days haven’t been common,’’ he wrote in an e-mail, “it’s fun to think optimistically and check the app to see if one might be on the horizon.’’

    D.C. Denison can be reached at