Heavy Rain/Snow, Winter Weather

Snowy Thursday Expected

“Luck. Runs. Out.” – Metallica

If you’ve been enjoying the relatively snowless and mild winter, then the opening line to the Metallica song “All Nightmare Long” is an appropriate line today, because your luck has run out. We’ve got a snowstorm coming tomorrow, and it’s going to impact both the morning and evening commutes, so plan ahead.

A cold front is moving across the region this afternoon, replacing last night’s unexpected cold air with milder air. Yes, that doesn’t sound right, but it’s what’s actually happening. As it moves offshore, it will stall out south of New England and high pressure will build in to our north, replacing the relatively mild air of this afternoon with more seasonably cold conditions tonight. At the same time, a wave of low pressure will ride along our stalled out cold front across the Tennessee Valley and into the Mid-Atlantic states. Once it moves off the coast early Thursday, it will intensify as it passes south and east of New England. With cold air settling in, and low pressure passing just south of New England, you get a snowstorm. It won’t be a blockbuster storm, since it’ll be moving too quickly, but we’re still looking at moderate to heavy snow.

gfs-prateptype_cat-us_ne-2017020812-loop

GFS model forecast for the progression of our Thursday storm. The darker blues are moderate to heavy snow. Loop provided by Pivotal Weather.

OK, time for some specifics. First the timing. This will be a 10-12 hour storm for most of us. The snow should develop right around the morning commute, roughly the 6-8am time frame. It should end right around the evening commute, roughly the 6-8pm time frame. The worst of the storm will be between about 10am and 4pm, when snow could fall at the rates of 1-2 inches (or more) per hour.

Next up – temperatures, since they have an impact as well. We’re going to have a boundary set up across eastern Massachusetts that is called a coastal front. We had the same thing happen last night. East of the front (right along the coast), temperatures will be in the upper 20s to lower 30s, resulting in a wet, heavy snow. West of the front, temperatures will be in the upper teens to lower 20s, resulting in a much drier, fluffier snow. Right along this boundary is usually where the heaviest snow falls. So, where does that front set up? Right now, it looks like somewhere right along I-95 across eastern Mass.

hires_t2m_boston_30

Temperature forecast for Noon Thursday based on the WRF model. Note the sharp temperature gradient across eastern and southeastern Massachusetts. Image provided by WeatherBell.

Next up, the winds. Strong winds will likely be confined to eastern Massachusetts, especially along the coast, as always. Sustained winds of 20-30 mph are possible near the coast, with some gusts to 50 mph. Away from the coast, we’re looking at gusts of 20-30 mph. Nothing like some of the worst storms we’ve seen, but it’ll creating blowing and drifting, reducing visibility at times.

So, that leads us to the part you’re all most interested in – how much snow are we going to get? For most of us, this will be a moderate snowfall event. Here’s the breakdown for what we’re thinking:

Central NH (Concord): 3-6″
Southern NH (Manchester/Nashua/Portsmouth): 4-8″
Merrimack Valley/Central MA (Lawrence/Lowell/Fitchburg/Worcester): 5-10″
Cape Cod: 5-10″ (maybe a little less on the Outer Cape/Nantucket)
North Shore/SE Mass (Beverly/Plymouth/Fall River): 6-12″
Rest of Eastern MA/RI (Boston/Providence/Brockton/Framingham): 7-14″ with isolated heavier totals possible.

6zgfs

This model (the GFS) most closely resembles our thinking for snowfall across the region. Image provided by Pivotal Weather.

Once the storm goes by, we’re looking at a breezy and cold day on Friday, with temperatures likely staying in the teens or lower 20s across the entire area. Then, Friday night and Saturday brings another Saskatchewan Screamer (Manitoba Mover? Albert Clipper?) which could drop a quick 2-4 ” of snow. There’s another storm right behind that for Sunday night into Monday, but the models are indicating that storm could feature more rain than snow. We’ll keep an eye on it anyways. The active pattern likely continues into next week as well.

Standard

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s