Sunday, February 4, 2018

Vermont's Snowy (And Slushy) Weather: An Update

Here's what the National Weather Service in South
Burlington is projecting for snowfall through early
Monday morning. (Click on the map to make it bigger
and easier to read.) Areas away from the Champlain
and Lower Connecticut River Valleys will
be the winners, with three to seven inches of new powder.
As of mid-morning this Sunday, snow was falling across much of Vermont and New York.

However, the flakes were pretty much avoiding the Champlain Valley. If you are in the Champlain Valley you also probably notice this morning it's windy from the south.

Winds are coming down the slopes of the Adirondacks and to a lesser extent the Green Mountains, and funneling into the Champlain Valley, causing the winds.

When the air first descends those mountain slopes, it dries, so we don't get the snow in the valley. Eventually, the incoming storm's moisture will increase, so it will start snowing the Champlain Valley this afternoon.

Those south winds are blowing in some warmer air, so especially near Lake Champlain. There, and in other low lying areas of Vermont, the snow will become wet and slushy, and even mix with or change to rain in some areas.

These two factors I outlined - the drying air in the Champlain Valley this morning and the warmish valley air this afternoon has a big impact on how much snow everyone will get, as you can imagine.

By the time this system ends late tonight, only one to three inches of snow will have accumulated in the lower Connecticut River Valley and the Champlain Valley. (with possibly a bit more in the far northern Champlain Valley. )

Places away from Lake Champlain and uphill from the Connecticut River Valley can expect a decent three to six inches of snow out of this by early Monday morning, giving the ski resorts a nice refresher layer o snow.

At this point, the National Weather Service is declaring the southern and central Adirondack Mountains of New York the big winner out of this otherwise modest storm. There, a winter storm warning is up for eight to 14 inches of snow. 

Everyone should get ready for a rather slow Monday morning commute, once again. It'll be a lot like Friday's rather cold, icy commute.

Here's why Monday morning will be difficult: The rather warm temperatures, wet snow and, in the warmer valleys, a mix with rain, will continue well into tonight. Late tonight, a sharp burst of colder air will rush in, turning all that slush to ice.

The wet snow will by then have been compacted into ice on the roads, and the incoming cold air will solidify that ice into really slick, thick stuff which will be hard to remove with snow plows and salt.

I am happy to report that, at least for the upcoming week, early projections of bone-chilling cold were overblown. There is incredibly cold air building up in Canada, especially near Hudson Bay and northern Quebec.

However, the core of the cold air will stay up there, and we'll be on the outer, southern edge of the deep chill. That means it will only be kind of, seasonably cold here in Vermont. Little pieces of this frigid air will occasionally break off and make us a little colder on occasion. It looks like the coldest days will be Monday and Friday. (Highs in the teens, lows near 0. Cold, but not ridiculous.) Most other days during the next week or so will feature highs in the 20s, not bad, really.

Depending on your perspective, being on the edge of a massive cold air blob in Canada, with warm, wet air well off to the southeast is good if like snow and ice, bad if you don't. This pattern puts Vermont right in a storm track. Which means we'll have active, and pretty unpredictable weather for awhile.

Another mid-sized, relatively fast moving storm will come by at midweek.  At this point, it looks like most of us will get a mid-sized snow out of this, with possible rain toward southeastern Vermont. A big caveat: If this thing takes a slight jog further north and west than is now predicted, more of us will get rain, and the snow would be confined more to the north and west.

If the current forecast does turn out to be correct,  this is all terrific for Vermont ski areas: Cold enough to make snow, and two decent natural snowfalls all coming right before the all important Presidents Week holiday.

Looking further ahead, it appears at this point at least, the massive cold blob in central Canada will stay there. But this is kind of an unstable weather pattern, which means we could end being surprised during the middle and second half of February with either an intense cold blast or two, or a real big thaw.

I always tell you to take weather forecasts beyond a few days with a big grain of salt. Right now, I'd say that grain of salt for forecasts beyond five days from now should be taken with a grain of salt at least as big as a Volkswagon, if not larger.

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