UPDATE 1 PM
NOAA's Storm Prediction Center has upped the chances of a brief tornado today in New York's northern Hudson Valley and the southern Champlain Valley of Vermont.
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| Back deck of my house getting a good wetting during downpours this morning in St. Albans, Vermont. Chances remain of severe storms this afternoon, especially from about Burlington south |
The chances of a twister are still very low, but not zero. I'm pointing this out because this area seems like a possible focal point for severe storms today. Skies seem the most likely to partly clear in this area, which will promote instability and the possibility of stronger storms.
Further north in northern Vermont, another band of showers, some pretty heavy were passing through at around 1 p.m. today. These showers seem destined to stabilize the air over the north today, somewhat minimizing the chances of severe storms. Even there, severe storms may erupt this afternoon, so keep your eyes to the skies.
PREVIOUS DISCUSSION
It felt sort of tropical stormish around my house in St. Albans, Vermont this morning. Heavy rain came down in sheets and waves, and gusty winds tossed the branches of the big poplars that are just outside my home office window.
This is all part of a rather dynamic storm for late August, one that could bring some severe weather later today.
To be clear, this morning's weather had nothing to do with a tropical storm, despite my description of the weather. It was a warm front passing through. Wet air was being lifted up and over some cooler air as the warm front approached, and that touched off the heavy rain.
All of Vermont needs the rain, but the southern half of the state needs it more. However, the heaviest rain went through northern parts of the state this morning. Oh well.
The warm front will get to a point a little north of the Canadian border by later this morning, and the air will take on a humid feel.
Then the set up: A strong cold front will be approaching from the west this afternoon. As the front approaches, the wind above us will change direction with height, and blow pretty strongly. That's a recipe for severe storms, even possibly rotating supercells, if things work out just right.
But will they?
We'll need quite a bit of instability for storms to really fire up. One way to get that instability is sunshine, which would heat the air near the surface, to contrast with colder air up above. This warm surface air, cold aloft scenario helps clouds billow upward into those towering thunderstorms.
The problem is, nobody is quite sure how much sunshine will develop late this morning and early afternoon to set the stage for those storms.
There was a narrow band of at least partly cloudy skies in parts of western and central New York early this morning. If that moves in and maintains itself, that could contribute to some severe storms.
As it stands now, all of Vermont is under a little bit of a threat of severe storms, with southwestern Vermont having the highest chance.
As is usual in these situations, most of us won't get blasted. If the strong storms form, they'll only affect localized areas. The biggest threat from any severe storms today would be damaging straight line winds.
Because there's a chance some of these storms might be rotating, there's is once again, a very minimal chance of a brief tornado. But don't hold your breath for that. Just take shelter in a sturdy building if your area goes under a severe thunderstorm warning.
The timing is such that the best chances of strong storms would be between mid afternoon and early evening. Do note that any thunderstorm that gets going, including the ones that aren't severe, could have a lot of cloud to ground lightning. You don't want to be outside in that. If you hear thunder, that's your alarm bell to go indoors.
After this cold front goes by, we're getting another shot of autumn like weather for the second half of the weekend It'll stay in the 60s all afternoon Sunday, with partly cloudy skies and perhaps a light sprinkle here and there.
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