From January 4 - 5, 2016, Cape Cod and eastern Massachusetts dealt with magnified snow bands, driven by anomalously warm ocean temperatures simply off the coast. While number of inches of snow on the Cape is nothing the end of the ordinary, what is inexplicable is the Boston and also areas in eastern MA just 10 miles far from the coast measured much less! What might be the culprit here?


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GFS modeled surface temperatures because that 00Z (7PM) on Monday, January 4, 2016 (courtesy Levi Cowan / tropical Tidbits). Note air temperature in the 20s passing simply off the Massachusetts coast.

You are watching: Does it snow over the ocean


Ocean effect snow is your answer! The physics space actually largely comparable to lake-effect snow, special cold air moving over lot warmer water. With ocean temperatures in the 45-48 degree selection off the coast, and also air temperature in the upper 20s, the 20 degree difference creates an unstable atmosphere in the lowest 4,000-5,000 feet. This unstable atmosphere leads to the advancement of snow bands, few of which could produce moderate to heavy snowfall rates. In fact, the sea surface temperatures just off the shore are to run 2.0-2.5 levels Celsius above normal, which helps rise the instability even more.


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Image displaying Sea surface ar Temperature anomalies turn off the MA coast on December 31, 2015 (courtesy NOAA). Yellow color coincides to 1.75 come 2.5 levels Celsius above normal.

But why go ocean result snow primarily affect the Cape?It all has to do v the wind direction. An extremely cold winds out of the phibìc are well known for occurring snow bands end the ocean and tossing them ideal over the Cape. If the wind move a bit to the northeast, some of these bands are able to move additional inland. Check out the picture from the high resolution NAM design for this evening (courtesy of the PSU e-wall), mirroring the meant placement of ocean snow bands.

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4-km NAM model image for 23Z (6PM) Monday, January 4th, 2016. Highlighted area with black circle mirrors expected location of ocean-effect eye bands. (image courtesy penn State e-Wall)

So next time ocean effect snow is predicted, you"ll know why this phenomena occurs. And if friend forget, just search out this valuable explainer.