Wednesday Evening Vermont Storm Update: Flash Flood Risk Peaking Now Through Midnight

A severe thunderstorm with torrential rain passing
just north of New Haven, Vermont Wednesday. 

 So far, as of 7:30 p.m., Vermont has sort of lucked out in terms of severe thunderstorms and tornadoes, but not so much with the flash flooding.  

It ain't over yet. 

True, the flash flooding hasn't been severe yet, but it is just now ramping  up.  Reports are just coming in, and that will accelerate through the evening.

FLOODING TONIGHT 

The flash flood risk is still very real for central and northern Vermont through the night. 

They worst of it seems to continue to be right along and just south of the extremely slow warm front across central Vermont.

A series of severe thunderstorms have been following each other in a zone running from the Adirondacks through a zone between Middlebury and Burlington, then through the area around Barre and Montpelier, and on toward St. Johnsbury. 

Each storm has dumped torrential rain, so flash flood warnings are up in that zone as the storms continue to train one after another along that path. 

Already, we have reports of water across a road in Panton, Vermont, rocks and water on Route 116 in Starksboro and more debris and water across Route 100 between Waterbury and Stowe.

As the particularly heavy rain continues along that rough Middlebury to St. Johnsbury path, it will work with the downpours they've already had to worsen flash flooding. 

It'll get dark soon, so driving around will be dangerous, as you can't see road washouts, flooding or debris on roads often until its too late.

North of Route 2 to the Canadian border, it's been raining hard most often afternoon and evening, but it hasn't been as torrential as central Vermont has seen. But the rain intensity should pick up as the evening wears on, so flash flooding probably will develop there, too.

LARGER RIVERS

The outlook for flooding on larger rivers has worsened, as I kinda thought it would. It still won't be anything nearly as bad as a year ago, but you'll still need to watch out overnight and during the day tomorrow. 

The Mad River has become particularly worrisome, with current forecasts having it go to just short of major flood stage before dawn. 

It still looks like Montpelier is still safe from another Winooski River flood, though that river should go above flood stage at Waterbury and Essex Junction. It still doesn't look like it will get nearly as high as it did last summer, or even last December, though. 

Ominous skies in New Haven, Vermont Wednesday. 

The Lamoille River should reach minor flood stage, but again, it shouldn't flood downtown Johnson or Cambridge. The Missisquoi River has potential to go into minor flood stage, too.

Be advised, if the rain tonight is heavier than expected, and the rushes of water coming off the mountains and hills are worse than we think they will be, the flooding on the main rivers will of course be worse.

Stay tuned! 

SEVERE THUNDERSTORMS

We lucked out in the sense that for a time during the peak risk hours for severe thunderstorms and tornadoes, some low level stable air unexpectedly crept southward in Vermont, especially in the Champlain Valley.

Storms were still able to erupt just above that thin stable layer near the ground, but that dense air on the ground kept thunderstorms from reaching their full potential, at least in terms of wind and tornado risk.  The storms still had plenty of space to produce torrential rains, so that has been the principal problem.

Many of these storms have been rotating, but again, the low level stable air probably prevented anything from forming and touching down. 

A few trees and branches came down in strong thunderstorm winds in parts of Addison County, but so far, I have seen only a few reports of that.  Several trees were reported down in Bridport, and a shaky video taken in Bridport and posted on Facebook shows something that at least resembles a tornado.

Cloud to ground lightning has been pretty impressive with these storms. At least one building fire has been reported in Addison County due to lightning. 

The low level feed to stable air is petering out, so some more severe thunderstorms are possible for at least a couple more hours. Severe thunderstorm warnings, in addition to the flash flood warnings, were in effect as of 7:30 across most of central Vermont. 

But the threat in general should begin to wane on that front.

THURSDAY AND BEYOND 

The very warm, humid weather remains in place through early next week. That means we'll be at risk of scattered showers and storms through that period. I suppose a couple storms might end up being strong enough on any given day to produce isolated flash flood trouble, but the risk seems pretty low, at least according to the latest forecasts.

There will be a big slug of moisture running up parts of the East Coast over the weekend with heavy rain, but that should safely pass well east and south of Vermont.