The first major winter storm of the season is upon us. The storm system that could bring upwards of 12-18″ of snow to Southern and Central New England has had an interesting life cycle as it has traversed the continental United States.  First it came ashore at near record strength along the Oregon and Northern California coast with a measured wind gust of 106 mph. Second it redeveloped into a blizzard for the upper plains where it dropped 1-2′ of snow in South Dakota.  And finally as a significant storm system for the northeast before finally exiting stage right out into the Atlantic and eastern Canada.

For New England, this system will really come in three parts.

Part 1: Overnight Sunday into Monday Morning

Sunday Afternoon Radar Loop – College of DuPage

The Sunday afternoon radar shown above highlights part 1 of this storm system. While the primary area of low pressure spins over the state of Indiana, warm, moist air is advected northward ahead of the system.  This surge of warm, moist air from the south leads to a burst of snow this afternoon and into the overnight.

One models projection for how part 1 plays out tonight is shown below.

Part 1: Sunday PM -> Early Monday AM – Pivotal Weather, LLC.

I picked this model simulation because it highlights a two important aspects of the forecast. The first being that as daybreak Monday morning approaches precipitation rates will drop off. The second being that warm air aloft may overspread SNE and flip many locals to sleet, freezing drizzle and perhaps plain rain.

Here is my thinking for snow totals associated with just Part 1 (i.e. what you wake up to tomorrow morning)

Sunday PM -> early Monday AM Snowfall

Part 2: Monday

During the day Monday will be an in between period with off & on precipitation as the surge of warm, moist air dies and the secondary low pressure forming south of the region gains steam.

Monday AM -> late Monday PM – Pivotal Weather, LLC

As shown above, precipitation rates aren’t very high during the day Monday and into the overnight hours. Many places will either receive light snow or freezing drizzle. Please be careful as some spots may be very slick.

The low pressure center which forms near the New Jersey coast will east-northeast passing near Nantucket Monday evening. As it does, the radar will fill back in and most areas flip back to snow.

Here is my anticipated snowfall accumulations for Monday. I included a plus sign in the ranges to cover those regions that may sit underneath a heavier snow band. Locally higher amounts are possible if a band sits over an area.

Part 2 Snowfall: Monday AM -> late Monday PM

Part 3: Overnight Monday into Tuesday (The Wild Card)

Now for the area of the forecast with the least amount of confidence. As the storm center intensifies east of the region, does it wrap up close enough to the coast to give eastern New England another round of heavy snowfall?

Here are two model projections where the first shows the upper end potential while the second shows the opposite.

Maximum Snow Potential Scenario: 7p Monday -> 7p Tuesday

Part 3 Max Snow – Pivotal Weather, LLC

Minimum Snow Potential: 7p Monday -> 7p Tuesday

Part 3 Min Snow Potential – Pivotal Weather, LLC

The difference between the two scenarios is obvious. The low pressure center wraps up in two completely different locations: 1) due east of Boston near the coast or 2) further northeast in the Gulf of Maine.

Latest computer model guidance has trended towards the maximum snow potential scenario, but the final outcome is likely somewhere in between.  Here is what I am expecting for snow accumulations from part 3.

Part 3 Snowfall: late Monday PM -> Tuesday AM

I included plus signs for eastern areas to cover the potential that all things break “right” and the amount of snowfall is maximized.

Storm Total

Storm Total Snowfall

Honestly this storm has a higher than normal bust potential and in both directions. I can foresee scenarios where my numbers are both too high and too low. This isn’t a typical set up and as such the forecast comes with a low confidence level. But the snow map above represents my best estimate at snowfall totals from Sunday afternoon through Tuesday morning.

-Chris


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