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You’re probably asking, why am I shoveling yet again?

Jack Crawford (left) and his dad Derrick Crawford walked back up the small hill at the Arnold Arboretum of Harvard University in Boston on Sunday.Pat Greenhouse/Globe Staff

Depending on where you live, you might be asking yourself this morning: How are there nearly 7 inches of snow on the ground and why I am out here shoveling once again? The past 24 hours have brought nearly continuous snow to parts of central and eastern Massachusetts, with the amounts piling up higher than expected, especially inland.

At the end of last week, it looked like there might be an inch of snow over Southeastern Massachusetts with some scattered snow showers inland. On Saturday, I got some signals that this was going to be more than just flurries and gave the forecast an update, moving accumulating snow well inland.


It still wasn’t enough. The past 24 hours have seen snow caused by two different meteorological reasons. The first half of Sunday brought snow as colder air clashed with the remnants of the mild air from Saturday. The lift, which is always necessary in the atmosphere to create precipitation, came about due to this temperature gradient. You likely noticed a lull in the action during the middle of the day before the snow started picking up again Sunday night.

On Friday it appeared only Southeastern Massachusetts would see accumulating snow, but on Saturday afternoon the models changed and moved the snow much further west. Dave Epstein

I knew Sunday night’s forecast was going to be tricky as the guidance I looked at was showing some areas with very little snow and others with 5 or 6 inches. The lack of uniformity meant there was going to be some small-scale phenomena creating more snow.

Seven inches of snow had piled up in Natick over the past 24 hours. Dave Epstein

Indeed this morning as I look at the weather maps, there’s a storm system way out in the ocean that typically would not have brought snow this far west. However, an elongated piece of the storm is sticking west toward the coastline. This westward-facing trough, with a shift in wind direction on either side, is creating enough lift in the atmosphere to bring about the snow.


During Monday morning, this area will rotate beyond Southern New England, meaning the snow will end and skies will clear.

Another reason the snow piled up so quickly over the past 24 hours: it was light and fluffy, allowing a lot of air between the flakes. The flakes themselves, also called dendrites, were perfectly formed, which meant they could layer up quickly as they fell.

This is one of the reasons I still love meteorology. In spite of the fact we get the forecast right most of the time, sometimes it still gives us surprises and an opportunity for reflection and being a better forecaster.

A westward-facing trough as denoted by the red line created lift in the atmosphere and brought snow to parts of Southern New England overnight. Dave Epstein

Skies will clear later Monday morning, and you’ll need your sunglasses this afternoon. Temperatures are going to remain cold, only in the 20s. It will stay very cold tonight and readings will fall down to the single numbers in many spots. I expect another cold day for Tuesday with bright sunshine before a significant warm-up occurs from Wednesday to Friday. Temperatures will reach the 50s at the end of the week. There will also be some showers Thursday night and much of the snow cover will disappear. The upcoming weekend looks sunny and dry.

Cold weather will continue all day Monday with temperatures about 15 degrees below average. Dave Epstein