Perfect Summer Vermont Weekend Continues; Deep Heat, Maybe Severe Storms By Tuesday, Tuesday Night

A beautiful blue sky with puffy clouds over St
Albans, Vermont yesterday. It was part of a near-
perfect weather weekend in the Green Mountain State.

 We're halfway through a perfect Vermont summer weekend, at least in terms of weather. 

On Saturday, the temperature was perfect. The humidity was perfect. The scattered puffy clouds were perfect. A pleasant north breeze was perfect. Wildfire smoke in the atmosphere almost entirely dissipated.  

It's been really warm lately, so by comparison, yesterday was actually the coolest day since June 27, at least as measured in Burlington. That "cool" weather involved a warm high of 82 degrees.

Enjoy it while you can. By Tuesday, things could get rough. More on that in a minute.

Meanwhile, if you somehow missed Saturday's weather, we'll do it again today. Details:

TODAY

We started the day with temperatures in the 50s, with upper 40s in the cooler spots. If you didn't sleep well last night, don't blame the weather. It was a perfect summer sleeping night. There's that word again. Perfect. 

The only real difference today is it will be a couple degrees warmer than yesterday. So, low to mid 80s. There might be a little more wildfire smoke in the atmosphere today, compared to yesterday. But it will amount to some haze at times.

Go out there and enjoy any outdoor activity you like. The only thing to watch out for is the sun. You'll need sunscreen.

MONDAY

Here's where the weather starts to go downhill. But just a little. Warm air from the west and south will start to flow in.  By afternoon, highs will get into the mid and upper 80s, maybe even flirting with 90 in the hottest valleys. The humidity will begin to creep up, but it will still be pretty reasonable. 

It should be mostly sunny, though a weak disturbance might touch off a few light showers, mostly in northern Vermont. But the chances of that are low. 

TUESDAY/TUESDAY NIGHT

This will be the real trouble day. The first problem will be the heat. We're calling it "jailbreak heat," a term I stole from the National Weather Service in South Burlington. It's "jailbreak"  because a piece of hot air will escape from a terribly torrid heat dome over the northern Rockies. That plume of hot air will be racing east across the far northern Plains, southern Canada and down across New England .

We'll start the day warm, and it will get hotter and hotter as the day goes on and the blast furnace air comes in from the west. 

By late afternoon, almost all of Vermont will be at least 90 degrees. The warmest valleys should make it into the mid-90s.  There's a slight chance that the warmest valleys could be in the 95 to 100 degree range, but statewide, 90 to 95 degrees looks like the safest bet. 

It'll turn more humid, too. But not as humid as in that heat wave that struck at the beginning of the month. The hot air won't have a direct connection to the steamy Atlantic Ocean or Gulf of Mexico. But southwest winds will bring in some moisture. 

STORMS?

The next problem with Tuesday will come late in the day, most likely after dark.  A southward moving cold front making its way into the hot air into Quebec will encounter a lot of atmospheric instability.

It looks like a large chunk of southern Quebec faces a nasty severe storm and tornado outbreak on Tuesday. 

By late in the day, that activity will start to cross the border into northern New England, including areas of Vermont near the Canadian border. 

NOAA's Storm Prediction has areas north of Route 2 in a slight risk of severe storms (level 2 out of 5 risk, with maybe a greater risk of high winds. The  rest of the state in a marginal risk (level one out of five).

That's a preliminary forecast. For now, the storms look like they will cross the border from Quebec into Vermont after dark, when the storms would be losing the atmosphere's strongest instability. They might be starting to weaken by then.  But they would still be powerful. 

Or, the storms could show up earlier, when they would be stronger.

In any event, all this is potentially dangerous for the campers enjoying Vermont's forests. Especially if these storms hit at night, when people are sleeping in tents or flimsy RVs. Falling trees in this scenario are obviously dangerous. 

An example of how dangerous could be a 1995 derecho that swept through New York's Adirondack mountains, killing seven people. 

Tuesday night's weather is something we'll really have to keep an eye on.