Forecast: A Pleasant Wednesday Before Much Colder, Arctic Air Ends Work Week

December 14, 2016

David Epstein

Another sunny and pleasant day is underway across the region with highs this afternoon nearing 40 degrees. It will feel comfortable in the sun with light winds and full December sunshine.

The moon was full last night and this has brought about unusually high tides once again. There is a coastal flood advisory posted for areas in green on the map below. If you are traveling along shore roads through Friday during high tide there may be some detours or closings.

The full moon and the proximity of the moon to the Earth is bringing large tides to the area this week. (Dave Epstein/WBUR)

After today, cold air is going to return for tomorrow and Friday. This air is straight from the arctic and means temperatures will average at least 10, if not 20, degrees below seasonal normals. The image below shows how the winds circulate in the northern hemisphere. The interesting parts of this image are the purple colors, which represent the areas of coldest air. Notice how a lobe of this circulating air moves over the northeast and then lifts away. That is our arctic air mass coming tomorrow and Friday and leaving for the weekend.

Winds spinning counterclockwise across the northern hemisphere will bring arctic air to the area this week. (Courtesy Tropical Tidbits)

As the air mass retreats, a storm will bring a period of snow, mixed precipitation and eventually rain to the area. This will occur Friday night and Saturday and could linger into Sunday as some rain.

There could be enough snow to plow in many areas Saturday morning. I will have an important update tomorrow and an even better idea on Friday.

You can follow my weather updates on Twitter at @growingwisdom.

Wednesday: Mostly sunny and pleasant. Highs approaching 40.

Wednesday Night: Clouds and moonlight. Lows in the low 20s in the coldest spots. Upper 20s Boston/Cape Cod

Thursday: Lots of sunshine and colder. A few snow showers possible. Highs in the mid- 20s before noon, then falling to the teens. Watch for a gusty wind.

Friday: Arctic air is in place, and it will be very cold and windy. Wind chills under 15 below. Highs in the teens to near 20 with sunshine.

Saturday: Some morning snow then rain. Highs in the mid- to upper 30s.

Sunday: Some rain and mild. Highs in the 40s.

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