DISCUSSION: In light of several nor’easters battering the Midwest and northeast of the United States in the past few weeks, it is interesting to view the factors that determine whether or not a storm has the right recipe for a snow day to be issued. Some states, particularly in the South (think Florida, parts of Texas, etc.), may close schools even though the projected forecast may call for only up to one inch over 24 hours. Other states, like those in the north central plains and Rocky Mountains, normally require much higher snow amounts to close schools. The following is a list of factors that determine calling a snow day with a quick description and/or example for each:
Timing – When the snow will fall, i.e. during the day, overnight, intermittent, when it will start and end
Snowfall intensity – 2 inches of snow in 12 hours vs. 2 inches of snow in 1 hour (the latter occurred recently in winter storm Quinn in the northeast). Snowplows have difficulty keeping up with high snowfall rates.
Ice accumulation – Causes hazardous driving conditions, even a thin layer can be dangerous
Ground temperature – Can be warm enough for falling snow to melt, may melt snow but refreeze overnight, can determine if traction is possible for tires when traveling, important on overpasses and bridges
Wind chill – protect the safety of students and staff
Power outages – current outage or extremely likely chance of losing power, some schools look at power outages in immediate surrounding area even if the school itself still has power
Non-weather factors - resources to remove snow, available snow days left, state testing make-up dates
Ultimately the decision to close school and issue a snow day is for the safety of students and everyone involved. Some of these factors are more relevant than others depending on where one lives. For example, wind chill is more prevalent in the Midwest while snowfall intensity and power outages can be a deciding factor in the Northeast. Those living in the South may not see much snow but can sometimes be the recipients of an abundance of ice.
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©2018 Meteorologist Nicholas Quaglieri