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Boston Weather: 55.0°F | Overcast


Snow Possible Sunday

By Angela Zalucha

And now, the moment you’ve all been waiting for: a true Boston blizzard! A low pressure system is currently brewing over the Gulf Coast (see it over Texas on the map?). The air over there is warm, meaning it can hold more moisture, which it picked up from the Gulf. The low pressure air will move eastward and then quickly get pulled up the much cooler Eastern Seaboard. Since cooler air can’t hold as much moisture, all the moisture brought over will be released, and we will get lots of precipitation (in this case, snow).

This type of weather phenomenon is called a Nor’easter. How much snow we’ll get is still up for debate. The position of the low is critical: too far northwest and dry air at the surface will reduce snowfall; too far southeast and the system will get pushed out to sea. Just right and the low will get caught up with a system dropping in from the great lakes. At this point, it is safe to say we’ll at least get a moderate amount of snowfall and some gusty winds Saturday night and Sunday.

The other factor that will give us snow is, obviously, below-freezing temperatures. The jet stream (an upper-level “river” of air) acts as a boundary between warm southern and cold northern air, and usually curves through the US and Canada. Last month the jet was consistently located north, leaving much of the country in the warm region (the warm January was not, contrary to popular belief, directly because of global warming). The jet has finally dipped south, characteristic of a more typical winter pattern, and that’s the cause of the recent chilly weather.

Extended Forecast

Today: Mostly cloudy. High 32 F (0 C).

Tonight: Cloudy. Low 20 F (-7 C).

Tomorrow: Cloudy with snow showers possible in the afternoon. High 30 F (-1 C).

Tomorrow night: Snowy and blustery. Heavy snow accumulation possible. Low 20 F (-7 C).

Sunday: Moderate additional snow accumulation. High 27 F (-3 C).

Sunday night: Partly cloudy and cold. Low 10 F (-12 C).