All I Want For Christmas is…More Snow!

2020-12-21 14:55:30.000 – Sam Robinson, Weather Observer/Engineer

 

Today is the winter solstice so I figured it would be a good day to write about snow. At the time of writing, the forecast for Christmas Eve through Christmas day looks pretty dreary. The chances of receiving the winter weather equivalent of “coal” this year seems increasing likely: heavy rain and warmth. This late fall/early winter so far has been very New England-like with bouts of snow and cold, followed by rain and warming. Up here on the summit, we have seen slightly above average snowfall for October, followed by below average snowfall for November, and with December so far being right around average if we continue at the current rate. Unfortunately, the forecast for the next week does not promise much in the way of snow, so we will need a late storm to boost us up to average. Although the low snow across the north is a disappointment to snow lovers like myself, it is also an inconvenience to ski resorts who are forced to make snow, as well as for us planning our weekly summit shift changes. By this time in a normal winter season, the snow cat would be the main and only form of transportation top to bottom. Lately we have had to decide between van and truck with chains, a combination of wheeled vehicle and snow cat, or simply just the cat. The lack of significant snow pack has also allowed the snow cat ride, which takes upwards of multiple hours normally, to take just over an hour because of the minimal amount of plowing we have to do to keep the road passable.

NWS Snow Depth of New England 21 Dec 2020

Oddly enough, snowfall is already well above average in southern parts of the region. Looking at the snow depth map for New England (above) it can be seen that south central NH and VT currently have the highest depths due to last week’s monster snowmaker. Those areas saw anywhere from 36 to a grand total of 44 inches of snow from just that single storm. To put it into perspective, the all-time record snowstorm for the state of New Hampshire is 49.5 inches The National Weather Service in Gray Maine, which covers NH and Western ME reported that over 24 inches of snow fell in a 4 hour period in Central NH. Yes, you read that correctly. That equates to an average of 6 inches of snow per hour! I cannot imagine what that must have been like. This very rapid accumulation of snow was thanks to a focused band of heavy precipitation due to frontogenesis and strong dendritic growth. Basically, there was very strong vertical motion in the atmosphere, matched with plentiful moisture and a zone of cold temperatures aloft. These conditions allowed the flakes to grow large while not using much moisture to form. Cold air at the surface allowed the snow to pile up with lots of trapped air in the snow pack. At this point in time those 40+ inch depths have settled down due to natural settling from gravity, as well as sublimation and any melting that has occurred over the past few days. With that being said, that area of the state still definitely holds the deepest snow depths.

In my home state of Massachusetts we received about a foot statewide from that storm, with some northwestern areas receiving about 2 feet. Unbelievably, NWS Boston says we have already received more snow statewide than we did the entire winter season of 2019! Needless to say, the southern half of New England is starting off winter on a snowy foot, while the northern half has some catching up to do. The overall pattern looks to remain relatively active, and cold air is close by so hopefully more snow is on the horizon. Fingers crossed this upcoming rain storm does not do too much damage to the existing snowpack and we can resume with our normal winter weather. After all, winter is just starting.

Have a safe and happy holidays, and remember to think snow!

 

Sam Robinson, Weather Observer/Engineer

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