Saturday Morning Vermont Update: Iffy Forecast On Big Storms Late Tonight, But Definite Dangerous Heat Coming

NOAA's Storm Prediction Center has a slight chance
(Level 2 of 5 risk) in New York and a marginal chance
(Level 1 of 5 risk) in Vermont of severe storms late 
tonight. There's more uncertainty in that storm 
outlook than normal due to an unusual weather pattern.

As the headline suggests, we have kind of a complicated forecast for the potential for possibly strong storms late tonight and Sunday. 

But there's no question dangerous heat is on the way for later Sunday through Tuesday.

We'll get to all that day by day as we usually do here. 

But first, we'll check in with the winds of Friday.

Those strong west winds Friday morning and afternoon led to tragedy across the pond from Vermont in Chazy, New York. 

Strong gusts toppled a large tree in Chazy onto a truck occupied by Chazy Central Rural School senior and star softball play Kennedy Columbus, 18, of Chazy, WPTZ reported.  The impact of the falling tree made the overturn and hit a utility pole, causing power lines to arc.  Columbus was set to graduate from high school next week. 

Here in Vermont, the gusty winds had power outages across the state peaking at about 3,500 at around 11 a.m. Friday.  

TODAY:

That cold front provided us a welcome clear and cool night last night. It was in the upper 40s and low 50s at dawn across Vermont this morning. I put on some fleece in the house early this morning for a time. I won't need that fleece in the coming few days, that's for sure. 

Most Saturdays over the past few months in Vermont have had bad weather, so today's going to be a treat. Highs will reach to near 80 under mostly sunny skies and comfortable humidity levels.

But our long streak of consecutive weekends with rain will continue late tonight. However, we still don't know whether that rain come in the form benign moderate showers or  dangerous thunderstorms.

TONIGHT/SUNDAY MORNING:

This is the complicated part of the forecast, so bear with me. 

A cluster of powerful storms formed in North Dakota yesterday. These things are known as Mesoscale Convective Systems or MCS.  

This thing spun off at least 13 tornadoes in North Dakota and caused some towns in that state to experience straight line winds of more than 90 mph.  

The MCS continued on across northern Minnesota and Wisconsin, on across Lake Superior and was headed into Ontario early this morning.  It's  running along the northern edge of extreme heat in the central U.S. and cooler air to the north.

That extreme heat is heading north and east toward Ontario, southern Quebec and of course us here in New England, so the MCS or a redeveloped version of it should continue on through Ontario and southwestern Quebec by tonight.

The big question is how this will affect us here in Vermont. 

Early estimates are the core of this dangerous complex of storms would pass through Quebec, up near or north of Montreal late tonight. 

As the National Weather Service in South Burlington explained it in their Saturday morning forecast discussion, there is sometimes a LOT of instability in these overnight situations just south of the core of the MCS. 

That could lead to some strong to severe thunderstorms after midnight and early Sunday. One scenario is that those severe thunderstorms would remain north of the border and be Quebec's problem. Mostly northern and central Vermont would just get some moderate rain and some dying garden variety thunderstorms.

Or, some of those severe storms could come south of the border, causing locally damaging winds and a chaotic early morning of lots of lightning, loud bangs of thunder, and torrential rains.

Outflow from the Quebec storms could briefly leave a cool pool of air aloft over Vermont Sunday morning,  which would then start to get overwhelmed by the hot, humid air coming in. Could this set off a few more strong storms for parts of Sunday? Possible, but we don't know.

These types of storms on the leading edge of hot air are some of the most difficult weather events to forecast. We won't know for sure what's going on until the system is practically on top of us. Which would be late tonight. 

Most of us are trying to sleep at that hour. So one way or another, we'll probably be surprised. 

THE HEAT

We do know the hot, humid air will blast in during the day Sunday. There's already heat advisories for the some of valleys of southern Vermont for the afternoon as temperatures there climb to near 90 degrees amid stifling humidity. 

The hot, muggy air will be firmly in place Sunday night and Monday. 

A rare for Vermont extreme heat watch is already in effect for the Champlain and lower Connecticut River valleys Monday. Actual temperatures in those valleys Monday will be in the mid to upper 90s, but it will feel like it's 105 or so out there. 

The rest of Vermont will be dangerously hot, too. As we've previously mentioned, this will go through Tuesday. 

I'll have  more on the heat wave in upcoming posts, but I figure we'll get through the storm potential for late tonight and Sunday first.