Tornado Confirmed In Vermont Monday, More Hot And Severe Weather Ahead

Radar image from last evening from the weather team at
WPTZ-TV.  This shows likely strong rotation and a
possible tornado near Marlboro and West Brattleboro,
Vermont around 10 p.m. last night. The close proximity
of the red and green colors shows wind blowing in 
opposite directions right next to each other, indicating
that possible tornado

UPDATE:

An EF-1 tornado in Addison, Vermont was confirmed by the National Weather Service office in South Burlington.

Among the evidence: A local resident, Levi Barrett, caught the tornado on video.  It clearly showed a twisting funnels, perhaps some sub-vortices within it.  The tornado is visible on video flinging tree branches and other debris into the air. 

The tornado crosses a road in the video, and frighteningly, a car appears to drive right into it. 

The tornado was on the ground for a mile and had top winds of 90 mph, according to the National Weather Service office in South Burlington. 

I'll have more on this later as more details are confirmed. 

 PREVIOUS DISCUSSION

Yesterday did indeed prove to be an interesting weather day in Vermont, as some of the stronger showers and small thunderstorms ended up rotating as expected.  This might or might not have resulted in one or two brief tornadoes in Vermont.  

Meanwhile, more  hot, humid weather is up for today through Thursday, with additional chances for more severe storms in that period. More on that in a minute. 

One rotating storm last evening shortly before 7 p.m. caused tree and property damage and a report of a 69 mph wind gust near the intersection of Routes 22A and 17 in Addison last evening. 

The small storm did show signs of rotation on radar. At least for a short while. However, it's unclear if the damage was from straight line winds or a short-lived tornado.  

Video still of a tornado in Addison, Vermont shows tree 
branches being lofted into the air. Video by Levi Barrett.
It was provided to WPTZ's weather team and posted
on Twitter by WPTZ Chief Meteorologist 
Tyler Jankowski 

The National Weather Service office in South Burlington announced they have people heading to Addison this morning to determine whether or not it was a tornado.  They'll probably be able to tell what it was that caused the trouble by looking at the damage pattern.  For instance, if trees in the damage zone fell in different directions, it would more likely be a tornado. If all the fallen trees point in the same direction, it would more likely be straight line damage. 

The National Weather Service says they will tell us by this evening what they think hit Addison.   

Another possible brief tornado might have hit last night at about 10 p.m.  around Marlboro and West Brattleboro, but unfortunately, I suspect we'll never know for sure. 

Radar images were fairly convincing, but not slam dunk proof that there was a tornado in that area. It seemed to have happened in a relatively remote area, and as of this writing, I'm not aware of plans by any National Weather Service office to investigate this. (It would be the National Weather Service office in Albany, New York who would go there, as Brattleboro is part of their coverage area).

The storm prompted a tornado warning for southwestern New Hampshire, including the cities of Hinsdale and Keene, but the rotation fizzled on approach to Keene and I'm pretty sure there was no tornado there. 

Further east, it appears there was likely another tornado in Poland, Maine, north of Portland. 

In any event, the rain with these storms was surely welcome.  A small minority of towns missed out with around a half inch of rain, but most areas in Vermont received around an inch of rain, give or take, from yesterday's system. As expected, the heaviest rain was in parts of the Northeast Kingdom not far from Jay Peak, where I saw some reports of over two inches of rain. The most I've seen so far is 2.77 inches in Derby Line. 

The light rainfall in southern and eastern Vermont is a big disappointment because that's been the driest part of the state and drought has been established there. 

NEXT UP: HEAT AND STORMS

Very warm and humid air will cling to us like a smelly wet blanket through Thursday, but there might also be a few moments of excitement here and there. 

Let's break it down.

Today

Marginal risk (level 1 of 5) for severe thunderstorms 
northern half of New England today. That somewhat
 higher risk in yellow in the western Great Lakes
represents our future on Thursday. 

Now that yesterday's warm front has gone by, the very warm,  humid air has fully engulfed us. It'll be in the 80s today with fairly high humidity.  The broad valleys will be in the upper 80s, and there could be a spot 90 here or there. 

The warm front's parent storm is still up in Quebec, and is flinging little mini cold fronts southward our way. There's not much to these little disturbances, but given the unstable air in place, they can trigger some strong storms pretty quickly. 

There's dry air aloft, so they don't have all that much moisture to work with. That's why forecasters say the storms will be widely scattered. Most of us won't even see a storm today.  Unfortunately, the storms, with their rainfall, are least likely in southern Vermont. 

Though today's storms will probably be relatively few and far between, any that do get going could well pack a punch. 

The dry air way up high is also relatively cool, at least compared to the air we're having to deal with down on the ground. That means the air is unstable. One of many things meteorologists look at when considering thunderstorm forecast is something called CAPE, or Convective Available Potential Energy.  This describes the amount of fuel available for storms, the amount of instability in the air. 

Generally speaking, if the CAPE value is over 1,000 in Vermont, there's a risk of strong to severe storms. Forecast CAPE levels are forecast to be between 1,500 to 2,500 in Vermont this afternoon, so the potential is there. 

Damaging wind gusts and large hail are the risks from today's storms. Atmospheric conditions are wrong for any tornado potential, so that won't be an issue today. 

 Things quickly quite down tonight and it will stay stuffy and uncomfortable for sleeping. 

Wednesday:

Probably the hottest day of the period, with a caveat.  Some forecasts call for quite a bit of sun, and very little chance of showers or storms, so that would bring the warmer valleys into the low 90s.

A few forecasts call for a fair number of afternoon thunderstorms Wednesday, especially over the mountains. The clouds and outflow from these storms would keep us a wee bit cooler, but still humid. If these storms develop, one or two could very briefly cause strong winds but there's no widespread severe risk in Vermont on Wednesday. 

Thursday

We're still at risk for quite a few severe storms on Thursday. Earlier guesses are southern and eastern Vermont and the rest of New England are most at risk.. But all of Vermont and eastern New York are also still in play here. 

Risk of severe storms for all of New England on
Thursday. Wind, hail, maybe even tornado?

An stronger than normal storm, and a stronger than normal cold front for this time of year will be approaching.  Especially if there's a lot of sun before all that gets here, we're in line for some big storms. 

Typically in these situations, the worst storms come near what is known as a pre-frontal trough.  A pre-frontal trough is basically a mini cold front that is running out ahead of the main, "real" cold front.

The timing of the pre-frontal trough, and the cold front itself is key.   If either comes through in the morning, then the risk of severe storms falls

If these come through in the afternoon, after the sun destabilizes the air, then we're in trouble. Especially in this case. 

Upper level winds will be almost the strongest on record for this time of year. If big thunderstorms get going, they can grab those strong upper level winds and fling those gusts down to the surface, on to us.  That would lead to some really serious downbursts in a few spots, which can cause a lot of damage.

Hail and even a tornado or two are also possible Thursday, depending on the timing of things. Stay tuned for updates! 

Beyond Thursday

The air behind the cold front isn't actually much colder, but it will gradually turn somewhat cooler and drier Friday and over the weekend. But it'll still be well into the 80s Friday and low 80s over the weekend. A rapid series of disturbances will keep the risk of scattered showers and storms going into early next week, but figuring out the extent and timing of any rain at this point is impossible.