Thursday, April 7, 2016

Surprise Seven Inch Snowstorm Northern Vermont, More Trouble Today

One of the decks at my St Albans, Vermont home, and
the surrouding landscape, were buried in a surprise
seven inches of snow this morning. Add caption
Well, that was a shocker.

I knew the current storminess at the end of a near record level April cold snap would yield some snow yesterday before going over to rain, but wow!

At my weather headquarters in St. Albans, in the northwestern corner of Vermont, I got seven inches of snow, count 'em, seven inches!

There's more weather trouble coming to Vermont later today and tonight. More on that in a little bit.

First, the Surprise Snow

VERMONT APRIL SNOW

That was easily the biggest snowstorm of the admittably paltry season here in St. Albans. There were no snowfall in the heart of the past winter that were this big.

The forecast had called for a thin slushy coating of snow last evening at most, so this was really a big, BIG surprise.

The heaviest snow was confined to far northern Vermont. Drive down to Burlington, Vermont, less than 30 miles south of St. Albans, and there was only 0.8 inches of new snow -- less than an inch.

By the way, that light snow in Burlington means that so far, 2015-2016 is still the least snowiest season on record in Burlington, in records dating back to the 1880s. However, if 0.3 more inches of snow falls this month, which is a distinct possibility, this WON'T be the least snowy winter.

Back up in northern Vermont, Belividere got 8 inches, here in St. Albans, as mentions we got 7 inches, as did Eden.

Another surprising thing about this snow was it all came while a stiff south wind was blowing. I've seen a few bigger snowfalls than this in Vermont during April, but I've never seen so much April snow with a south wind.

All the other big April snows in Vermont involved some variation of a north wind. Maybe northeast or northwest, but not south. This really was a weird one.
Seven inches of snow in my backyard this morning.
The snow never got that deep anytime during this
past winter here in St. Albans, Vermont.  

The reason it snowed so much in far northern Vermont was a warm front ever so slowly trying to push out the entrenched cold air.

The warm air flooding in lifted up and over the cold air still entrenched mostly north of Route 2 in Vermont, condensed and fell as snow.

Areas south of Route 2 got little or no snow because they were south of the warm front, and south of a  moisture feed riding up through the Midwest, then turning eastward across the Great Lakes, far northern Vermont and northern New England.

The reason the forecasts were wrong about the snow was because most computer models placed the core of the colder air and moisture with the warm front more to the north, in Quebec. There wasn't supposed to be that much precipitation of any kind in northern Vermont.

Ooops.

As of 7 a.m. this morning, the snow had stopped, the warm front was in Quebec, the temperature had risen above freezing pretty much everywhere in Vermont and the snow is starting to melt.

Which leads us to our next weather problem today.

FLOODING?

A surge of warmer air is flooding into Vermont today. It'll easily get into the 50s in many areas. That's not far from normal for this time of year, but it's decidedly warmer than it's been.

The warm air is wet, and associated with a pretty vigorous storm. It's going to rain pretty hard later today and this evening across much of Vermont. Many areas will get close to an inch.

That's enough to cause rapid rises on streams and rives. Where there was little or no snow in central and southern Vermont, there will be little or no flooding.

In far northern Vermont, I have to wonder if the abruptly melting snow cover, the fast warmup v  and the downpours will lead to flooding.

I don't think the flooding will be super severe or widespread up north, but it's definitely something to watch.

If you live in a low spot, or will drive tonight on roads prone to flooding, be careful!  It's hard to see flooding at night, and you don't want to drive into three feet of cold water, or into a water-filled ditch because the road washed out.

By the way, there is a flood watch up for much of Maine, due to predicted heavy rain and snowmelt. And there's coastal flood advisories along parts of the New England coast due to astronomically high tides and strong south winds.

MORE SNOW AND WINTER?

Next, another big cold wave is coming into Vermont. Aren't you excited?

This next one won't be quite as intense as the one we just had, but it will be pretty big for April. And it will be accompanied by more snow.  Not another big snowstorm for Vermont, but still.

Temperatures will fall Friday amid rain and mountain snow showers in Vermont. The snow level will gradually fall all day Friday.  Wet snowflakes might be falling in the valleys by evening.

There won't be an organized storm,  just rain and snow showers. A few inches might pile up on the northern Vermont mountain peaks, but nothing in the valleys.

Friday night, there might be a light coating in the valleys as temperatures go below freezing, but knock on wood, I doubt places like St. Albans will get another seven inches. Burlington could conceivably get the 0.3 inches that would prevent the winter of 2015-16 from being the least snowy on record.

Saturday looks very cold, and rather interesting. Temperatures during the afternoon in Vermont and the rest of New England will barely get above freezing and a few places won't even do that. It'll get into the teens once again in many towns Saturday night.

The reason I said things will be interesting is the next cold wave will be caused by another very sharp dip in the jet stream, similar to the one that set up last weekend.

Like last weekend's cold snap, there will be fairly intense disturbance flowing through the dip in the jet stream.

One of those disturbances looks like it might spin up another fast developing storm in southern New England Saturday.

It's unclear still whether the storm will be close enough to the coast to drop snow on southern New England as it really winds up, but it definitely could. Places like Hartford and Boston could get their third snowfall this month, a big rarity for April.

It doesn't look like this potential weekend storm will bring snow to Vermont. There will just be some random snow showers blowing around that will drop dustings here and there.

After another brief warmup and rain early next week, another cold wave comes in the middle of next week. That next cold spell won't be as bad as the one we're getting Saturday and Sunday, and nowhere near as bad as the one last weekend.

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