Weather

Spotty Precipitation Ending, Rainstorm Late This Weekend

Along parts of the coast, spotty precipitation has been falling for a couple of days, but hasn’t amounted to very much. The further inland you are the less snow or freezing drizzle there has been.

There will be some icy roads in places this evening, so be aware of the changing road conditions as you head home.

I’ll be updating the forecast on Twitter @growingwisdom

While this system has been more of a nuisance, another stronger storm will move into the area on Sunday night. As amazing at it may seem, after all the cold air of the past 10 days, we are actually looking at primarily a rain storm.

There’s a term meteorologists use when describing a storm whose center goes west of the coastline. An “inside runner” as they are called, is able to circulate warm and moist air off the ocean far enough inland to cause rain to be the predominant precipitation type. This becomes particularly true along the coast and a number of miles inland.
In order to get a snow storm in the big cities of the northeast a storm needs to stay offshore far enough to keep that warm air at bay, but come close enough to hit those areas with the heaviest snow.

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Back in October when a parade of coastal storms began it appeared we might be in for a stormy winter. Indeed, the Thanksgiving storm brought one of the heaviest early snowstorms to the region.

In December, the storminess continued, but these storms didn’t have enough cold air to keep the precipitation snow and the track of several of the December storms was too far inland.

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This weekend we have another coastal storm developing, but like those in December the track of the storm will be too far inland to allow the cold air to remain.

This means a shot of rain, not snow for much of New England. The northern and western ski areas might see some snow to start, depending on the exact track of the storm, but unfortunately, this storm is another bummer for skiers.

The storm will intensify rapidly late Sunday and Monday as energy from the jet stream feeds the system. A simple was to understand how the jet stream interacts with storms below is this way. If the jet stream’s position is aligned over a storm correctly, the jet stream supports the lifting of air off the ground which in turn yields clouds and precipitation. Of course, it’s much more complicated than this, but the upper winds are a major factor in why storms do or don’t develop.

The map below shows the forecast position of the jet stream Sunday night. This flow will propel the storm up the coastline and bring a slug of precipitation through the region. The heaviest of the rain appears likely to fall either during the second half of the Patriot’s game Sunday night or even in the early morning hours of Monday morning.

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The storm pulls north and east into Canada later Monday and makes way for another shot of cold air for much of the week. For now, any January thaw is going to be more on the order of hours, not days.

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