Intense Flash Flooding In Northeast, And Ontario, Some Vermont Flood Risk Today

Extreme flooding again, this time in Connecticut on
Sunday. Photo from WINY Radio via Facebook. 

 While we in Vermont were harassed by scattered, mostly light showers and overcast skies on Sunday, new outbreaks of intense flash flooding hit other areas not too far from the Green Mountain State. 

Parts of Connecticut were under a flash flood emergency when up to ten inches of rain deluged the southwest parts of the state in a matter of hours. That led to a disaster on par with what happened around St. Johnsbury and Lyndonville on July 30 when eight inches of rain fell in a few hours there. 

The flooding in western Connecticut Sunday was described as a one in a thousand year flood event, which means the chances of what happened yesterday in any given year is 0.1 percent. Of course, in the age of climate change, I think this percentage chance need to be altered.

Up to ten inches of rain fell in just a few hours. In some western Connecticut towns, up to six inches of rain fell in just three hours. 

Unfortunately, reports are two people were swept away in the Connecticut flooding but deaths had not been confirmed as of this morning.

As you'd expect damage is severe, with many roads washed out. Homes and businesses are trashed. The same story we've heard way too often this year.

Meanwhile, in Ontario, five inches of rain drenched Toronto Saturday, setting off new rounds of flooding in a summer that has already seen intense flooding in Ontario.  Once again, people had to be pulled from cars suddenly stranded in rapidly rising water. 

This will be Toronto's wettest summer on record, according to Environment Canada.   The wettest summer on record in Toronto was previously 15.6 inches of rain, but already this summer, they've had 18.73 inches and counting. 

Here we go again. Vermont under a slight
risk for flash flooding today. 

I'm struck by how frequently the floods have been in the Northeast and southeastern Canada this summer. Central and northern Vermont on July 11. Vermont's Northeast Kingdom on July 30.  Toronto, Canada on July 15 and August 17. Montreal on August 2. Now Connecticut.

MORE FLOODS?

Today brings one last day for awhile for some flood threats in New England, including here in Vermont. 

The cold front that promises to bring in that chilly air we've been advertising is set to come through today.  NOAA's Weather Prediction Center has upgraded us from a marginal to a slight risk of excessive rain and flash flooding across Vermont today.

That is level two out of four-point scale. 

These risks are always tricky to assess in advance.  Sometimes, the heavy rain moves right along and doesn't linger over one area, minimizing the flood threat. Other times, heavy downpours hit the same area over and over again, and you have a local flash flood.

Today is kind of a tossup, so we'll have to wait until this afternoon to see how everything behaves. 

We know the line of storms ahead of today's cold front will have some torrential downpours. It's just a question of whether they linger over a particular spot for a couple or few hours.  Especially if it lingers over the Green Mountains, that could cause trouble, as the rainwater would gush down the steep slopes and cause some flash flooding.  

If we get any flash flooding in Vermont today, it'll happen between 1 and 8 p.m., says the National Weather Service in South Burlington.  Any flash flooding would take the form of washed out culverts, gravel roads and ditches, flooding of the type of small streams that rise quickly in heavy rains, and street flooding in urban areas. 

I don't think flash flooding today will be super widespread. Most of us should only get 0.75 to 1.5 inches of rain, which is manageable. But a few unlucky spots could get much more. 

The National Weather Service said this morning the ground is still so soggy that we can only handle 1.5 to 2 inches of rain in an hour before flash flooding would probably begin. Some towns that get hit by the heaviest downpours today could see that much rain in such a short time period. 

Seek higher ground very quickly if your area goes under flash flood warning.

We won't have to worry about flooding along main rivers like the Winooski, Lamoille, Missisquoi, Mad rivers and Otter Creek.  Those rivers will see sharp rises overnight, but won't go over their banks or cause anything scary or really damaging. 

I always hate to talk about flash flood risks because we Vermonters are so jumpy now when it comes to floods.  It's happened so much and so frequently, any forecast that mentions flooding probably triggers PTSD in more than a few people.

But, it will be over by this evening, so at least we don't have to sit and worry for very long.

COLD SNAP

As the chilly air pours in this evening, any Vermont flood risk will evaporate for the foreseeable future. The cold air in the atmosphere will probably trigger a fair number of rain showers Tuesday, Wednesday and possibly part of Thursday.  But all those showers will be light and pose absolutely no flood danger. 

After that, it should stay dry until at least next Sunday, or possibly even longer.