Slushy Storm To Bring More Snow, Rain To The Area Tomorrow Into Sunday

Hello everyone!

Another storm is on the way this weekend and while much of the Northeast US sees rain and 40’s for this storm, we lucky Northern New Englanders will likely be seeing more snow. While this will not be a big storm by any means, especially compared to others this winter, it will put a temporary pause on the arrival of Spring.

Water Vapor Image From This Afternoon Showing The Two Features That Will Bring Snow To The Area This Weekend. Credit: SSEC
Water Vapor Image From This Afternoon Showing The Two Features That Will Bring Snow To The Area This Weekend. Credit: SSEC

Looking at the setup for our weekend system, two main features present themselves: a plume of moisture and warm air heading north from the Gulf Of Mexico and an Arctic disturbance racing SE to meet the moisture. How much cold makes it south and how far it gets will be crucial to determining how much snow falls.

12Z GFS Valid At 1 PM Tomorrow Showing Warm Air Streaming In At 2500 Feet. Credit: Accuweather
12Z GFS Valid At 1 PM Tomorrow Showing Warm Air Streaming In At 2500 Feet. Credit: Accuweather

Before precip even starts, SW winds aloft will be allowing warm air to stream into southern parts of the region resulting in very little snow on the front side of the storm. Winds aloft are far weaker inland and thus above freezing air should be mainly a coastal issue with the foothills briefly getting in on the action tomorrow afternoon.

12Z NAM Showing Warm Air Working In Aloft But Staying Firm At The Surface. Vertical Temp Profile For Augusta, Valid At Midnight Tomorrow
12Z NAM Showing Warm Air Working In Aloft But Staying Firm At The Surface. Vertical Temp Profile For Augusta, Valid At Midnight Tomorrow. The Red Line Indicates The Temperature.

Warm air will also be working in at the surface but with 1-3′ of snowpack still on the ground, warming aloft may outpace the warming at the surface tomorrow morning so a brief period of sleet/freezing rain  is possible along the coast and just inland as well. While this doesn’t look like a major concern, watch out for some extra slick spots tomorrow morning.

12Z GFS Showing A Lack Of Intense Upward Motion Resulting In A Lack Of Heavy Precip. Image Credit: Accuweather
12Z GFS Showing A Lack Of Intense Upward Motion Resulting In A Lack Of Heavy Precip. Image Credit: Accuweather

Another key difference between this storm and others this season will be that precip this time around will be a lot more on the steady side rather than extremely heavy. The GFS vertical velocity map above shows this well. Notice the lack of pinks/reds and the introduction of more gentle oranges. This translates to light to moderate precip rather than heavy precip.

precip type map
Expected Precipitation Type For This Storm

By tomorrow afternoon, the warm air will have made its farthest push inland with temps both above freezing both aloft and at the surface all the way into the foothills. During the heaviest rain, flooding could be an issue along the coast where rain and snowmelt could combine to cause some minor street flooding Saturday afternoon/evening. Any impacts from flooding should be minor but it is something to watch for especially along the coast.

12Z GFS Showing A Strong Upper Low That Will Help To Extend Snow Well Into Sunday. Credit: Accuweather
12Z GFS Showing A Strong Upper Low That Will Help To Extend Snow Well Into Sunday. Credit: Accuweather

The final phase of the storm will come Sunday as an upper low dives SE across the area. This will help to continue snow across the area on Sunday which is when coastal areas see most of their accumulations. Flakes will be flying as far south as SE MA but no accumulation is expected south of Boston.

12Z Canadian Model Showing Snow Lingering Into Sunday Afternoon. Map Valid 1 PM Sunday. Credit: Weatherbell
12Z Canadian Model Showing Snow Lingering Into Sunday Afternoon. Map Valid 1 PM Sunday. Credit: Weatherbell

Snow on Sunday will be lighter and more showery in nature but it will help to keep roads slick and flakes falling for most of another day.

snow map 3-13

Taking a look at accumulations, the highest totals will be in the mountains where the cold air will hang tough the whole way through. Amounts drop off towards the coast with Southern New England seeing no accumulation at all.

I’ll have another update in the morning.

-Jack

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