Heavy Rain/Snow, Winter Weather

Here We Snow Again

We had a blizzard on Thursday and some light snow this morning. So, you’re all set with snow for a while, right? Good, you get a 24-hour break. We’ve got another storm coming for Sunday and Monday, and this one is looking like it will be another significant one.

Low pressure currently moving across the Plains states will move into the Ohio Valley tonight, then off the Mid-Atlantic coastline later on Sunday, passing just south of New England. It is then expected to slow down in the Gulf of Maine Sunday night and Monday while rapidly intensifying. Cold air is already in place today, and some spotty freezing drizzle or flurries are possible this evening into Sunday morning. The steadier precipitation from the storm should arrive around midday Sunday, in the form of snow, and may quickly become moderate during the afternoon hours. A coastal front will likely set up once again, with temperatures in the lower to middle 30s to the east of it, and upper teens to lower 20s west of it. As this front pushes inland, snow will change to rain during the late afternoon  or evening from Boston southward. Inland, we may see a little freezing rain or sleet mix in, but it should be mainly snow. As the storm begins to intensify in the Gulf of Maine Sunday night and Monday, this coastal front will collapse back towards the coast, changing everything back to snow, as gusty northerly winds send cold air back across the region. Snow continues into Monday morning, before tapering off around midday, though some snow showers may continue into the afternoon.

nam-refcmp_ptype-us_ne-2017021112-loop

Forecast from the NAM model for the upcoming storm. Loop provided by Pivotal Weather.

Having said all that, there are still a few details to be worked out:

1. How close does the storm come to the South Coast/Cape Cod.
2. How rapidly does the storm intensify in the Gulf of Maine.
3. How close to the coast does the storm slow down in the Gulf of Maine.

We need to resolve the factors to get a truly accurate forecast, but unfortunately, most of that won’t be known until the storm is ongoing. We are fairly sure that the strong winds will be confined to coastal areas, and mainly on Monday as the storm really intensifies to the east. Sustained winds of 25-35 mph with gusts to 50 mph or more are possible, especially from Cape Ann to the South Shore and Cape Cod.

So, by now, you’re wondering, how much snow this time? Here’s what we’re thinking:

Cape Cod: 1-3″, mainly Monday from the backlash behind the storm.
South Shore/Boston/Providence: 4-8″, possibly a little more, especially the further inland you get
MetroWest: 5-10″
Merrimack Valley: 8-12″
Southern NH/MA North Shore: 10-14″
NH Seacoast/Southern Maine: 12-16″

hires_snow_boston_61

The High Resolution NAM model most closely resembles our forecast for the upcoming storm. Image provided by WeatherBell.

We may revise this forecast late tonight or Sunday morning, if time allows. Also, just to give you fair warning, we may be dealing with yet another snowstorm in the Wednesday/Thursday time frame.

 

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