Blizzard, Winter Storm Warning's Posted For Southern New England

 

The National Weather Service Boston office has issued a Blizzard Warning for parts of Southeast Connecticut, all of Rhode Island, and all of Eastern Massachusetts. A Winter Storm Warning is in effect for the rest of Worcester County, Eastern Hamden, Hampshire, and Franklin Counties, and most of Connecticut. 

• A blizzard warning is issued when visibility is less than ¼ of a mile due to falling or blowing snow, with sustained winds or frequent gusts over 35 MPH for 3 consecutive hours. 
• A winter storm warning is issued when 6” of snow is expected in less than 12 hours OR 8” of snow in 24 hours. 

For a refresher on how the storm will form, please see last night's blog.

Big Picture

Here are the latest headlines from the National Weather Service.

NWS Boston Headlines

The headlines are in effect from Midnight tonight until 5 am Sunday. The main reason Worcester County is not under a blizzard warning is due to uncertainty of the winds meeting the blizzard threshold. The current national radar does not look ominous at all.

College of Dupage Weather Center Simulated Radar

The surface map from 10 AM this morning is a bit more busy. You can see our 2 pieces of energy moving towards the Carolina coast. A new low is beginning to form off the Southeast coast.

WPC 15z Surface Analysis (10 AM) 

This will be our storm. You can almost see the baroclinic leaf beginning to take shape on the low level water vapor satellite loop. The southern stream is visible across the Southeast while the Northern Stream is diving through the Ohio Valley.

GOES-16 Low Level Water Vapor Loop (Image College of Dupage Weather Center)

The low will deepen as it moves north/northeast this evening. The progression at the surface from 1 PM today to 1 AM tonight

WPC Surface Analysis/Fronts Friday 1 PM to Saturday 1 AM

Impacts and Hazards

Snow begins to fall around midnight. Expect 3-6" by 7 AM. There is plenty of Arctic air available so snowfall ratios will be around 15-20-1, instead the standard 10-1 ratio. Watch temperatures fall from the low 20s to teens across interior Southern New England from 1 AM to 7 AM

12z NAM Hires 2 m temperature Sat 1 AM, Sat 7 AM (Image Weathermodels.com)

Temperatures are in the low 30's across Southeast MA, the Cape and Islands. This is concerning because the snow will be heavy and wet here. The Cape and Islands will also see stronger winds so the threat of power outages is substantial in these areas. The gradient will also help enhance snowfall rates to the west.

12z HRRR 10m winds Saturday 8 am to Sunday 12 AM (image WeatherModels.com)

I'd take these winds gusts with a grain of salt but they give a good approximation of the the timing and areas that will see the strongest wind. That said, it also shows that the chance for blizzard conditions in Worcester County is still alive (yay!)(yay?). 

Timing and Totals

Snow will wind down between 5-7 pm in Western and Central Southern New England. Snow may linger longer in Eastern MA. I still think most towns see 1-2 feet. I think Southern Worcester County will see 18-24", with 12-18 more likely across Western MA and even less into Berkshire County. I think 18-24 is also the best bet across Northeast MA and Rhode Island. I would expect the jackpot to be in Southeast Massachusetts where 24-36" will be the norm. 

NWS Boston Snowfall Forecast

I would take the 18-24 and extend it into Eastern CT but otherwise I think the National Weather Service snow map is a good one. One final note; there was some extreme snowfall totals showing up on some of the computer models. As a rule I try to avoid forecasting weather that has never happened before. But a few totals approaching 40" are possible if they sit under intense snow for several hours. 

Thanks for reading and look for some updates tomorrow.