Severe Storm Risk Is Still Iffy In Vermont Today. Rain And Much Cooler Weather Tomorrow Is NOT Iffy

A severe thunderstorm over Lake Champlain in July, 2023.
Severe storms are possible in Vermont today, if
the right factors come together. We won't know until
shortly before the storms develop. 

 We're starting the day really mild, especially in the Champlain Valley, where temperatures were in the low 60s at dawn.

Such warm temperatures to start the day might make you feel like that risk of severe storms today will come true. After all, summer-like temperatures equal summer-like storms, right?

Well, maybe.

Meteorologists are not much closer to figuring out today's severe weather risk than they were yesterday. 

As the National Weather Service in South Burlington said in their overnight forecast discussion, we're reduced to "nowcasting," which means we'll only know whether any severe weather looms just hours or even less than an hour before they actually hit. If they hit. 

NOAA's Storm Prediction Center still has northern New York and northern New England under a marginal risk of severe weather today. That's level one of five, the lowest alert level. The SPC is also sort of into "nowcasting" with this, saying they'll upgrade to a level 2 slight risk if later forecasts increase the amount of instability in the air 

For Vermont, the marginal risk covers the entire state except areas right along the Massachusetts border. 

One limiting factor might be what was going on just after dawn today.  Light rain showers were over the Champlain Valley, and somewhat more substantial showers were in central New York, heading east towards us. 

NOAA's Storm Prediction Center has for now
kept a marginal risk of severe storms over norther
New England (dark green shading). I the risk
of storms seems to increase later this morning,
it'll go to level 2 slightly risk, like what you
see over Arkansas in this map. 

Showers and clouds this morning would tend to suppress instability, and that would more or less squash severe storm potential.  If skies clear up by early afternoon, we could maintain the instability and fire up the storms.  

The amount of moisture in the air is another key factor. Some forecasts show slightly higher humidity today than what was thought yesterday,  which is good if you want storms. 

But other forecasts mix drier air from aloft down to the surface this afternoon, which would lower the humidity. Pick your poison, I guess.

The wind situation thousands of feet overhead are great if severe storms are your thing. If storms can get going, they have the chance of "grabbing" pieces of that high speed air and bringing it to the surface as damaging wind gusts. 

Whether these storms develop depends on whether an approaching cold front can team up with enough instability from sunshine to allow thunderstorms to erupt. If, by noon it's nice and sunny out, we have a  good chance of some good storms to fire up. If it's cloudy and showery, you can't necessarily kiss the severe storms goodbye, but the chances of them actually happening get pretty low
. 

NOAA says if we do see severe storms today, they'll take the form of either what they call bowing echoes or brief supercells. 

Bowing echoes are short lines of thunderstorms. If you look at a bowing echo on radar, the line of storms is shaped like a backwards "C"  The front part of that backwards "C" that sticks out ahead of the rest of the line of thunderstorms is where you'd see those damaging wind gusts. 

Or, we could see some brief, or what NOAA calls transient supercells. It makes it sound like those poor supercells are unhoused. What they really mean is the supercells wouldn't last as long as they usually do. Midwestern supercells can last for many hours. In this case, not so much. 

Still, those "transient" supercells can cause damaging winds and maybe some hail.  Since supercells tend to spin, we'd still have a very, very, very, low risk of a brief tornado. A low risk but not no risk. 

If we do get those rambunctious thunderstorms, they'll come through between about 1 and 6 p.m. today. 

Overall, most of Vermont will not see severe storms today. If we get any damaging winds from the storms, it would be in just a few spots. But we don't know which spots yet, so keep an ear to weather radio or reliable weather forecasting sources like the National Weather  Service or the local TV meteorologists for updates. 

Other than the storms, today will be breezy to windy, especially in the Champlain Valley. Most of us will get well into the 70s before the showers or storms arrive. 

TONIGHT/TOMORROW

Meteorologists aren't sure about today's thunderstorms, but they are sure we're going to get pretty damned wet overnight tonight and tomorrow

Today's shower and thunderstorms will evolve into a steady rain tonight which should pretty much continue through Wednesday. It's looking like a nice soaker, which we need. 

Total rainfall today through tomorrow night looks like it'll amount to more than inch across most of Vermont. Some areas of central Vermont, especially in and near the Green Mountains, could close in on two inches. 

Aside from brief, torrential downpours if thunderstorms develop today, the rain will come down at a slow enough pace that means we shouldn't see any flooding. Rivers will rise and become turbulent, of course, so kayaking in them is probably a bad idea for a couple or few days. 

The weather misery index of Wednesday is really high, though. With the steady, day-long rain, temperatures should only hold near 50 degrees, except maybe somewhat warmer than that in far southern Vermont. 

AFTER TOMORROW

We still have another round in which we spend several days with below normal temperatures and a risk of showers at almost any time. Aside from tomorrow, it won't be as cold as it was last weekend, with highs most days in the mid 50s to low 60s.  Sunday might actually be a little warmer, getting into the near-normal 60s. 

This pattern still looks like it will hold more or less in place through at least May 18 or so.  Most of the showers between Thursday and May 18 are looking very much on the light side, at least so far. That means it's actually good that Wednesday will be so miserable and rainy.  

Risk Of Severe Thunderstorms In Vermont Today, First Big T-Storm Day of The Year Possible

There's a level two out of five threat of severe 
thunderstorms in yellow shading. That includes
southern Vermont, eastern New York and southwest
New England. There's an even greater chance of 
severe storms in parts of the Upper Midwest today. 

You know it's spring because we in Vermont have our first threat of severe thunderstorms of the season today. 

A few areas in the Green Mountain State could see strong to damaging wind gusts in a few of the storms that could form today. 

The best chances of a severe storm are south of a line from Saranac Lake, New York to Lebanon, New Hampshire, the National Weather Service office in South Burlington tells us.  

That's basically along and south of Route 4 with the risk getting into the southern Champlain Valley as well. The risk in this area is level 2 out of 5 point scale. 

All of the rest of Vermont except maybe the extreme northeast tip has a quite low, but not zero chance of an isolated thunderstorms with potentially damaging winds. 

The culprit is a cluster of thunderstorms in the central and eastern Great Lakes early this morning. They're the leftovers of severe weather that sent a few tornadoes swirling through northern Iowa, southern Minnesota and Wisconsin yesterday. 

During the heat of the day, as these storms approach us in northern New England, they might strengthen again. Not nearly enough to give us a round of tornadoes like in the Midwest, but give us the risk of strong winds. 

A "NOWCAST" DAY

The National Weather Service is calling this a "nowcast day." There are so many moving parts that have to line up, or not line up to produce our thunderstorms. And determine how rambunctious they'll get. And where they'll hit.

We won't really know for sure how this is going until things start to bubble this afternoon. Especially going to spend the day outside, you'll want to have a way to hear special weather statements, forecast updates and possibly severe thunderstorms watches or warnings. 

Remember, a watch means maybe. Think of it is as your mother calmly calling you in,  using your nickname. A warning means a severe thunderstorm is coming. That's your mother, angry, urgent, using your full name to get yourself inside. "JOHN MATTHEW SUTKOSKI, GET YOUR ASS IN THE HOUSE NOW OR YOU'LL REALLY HAVE SOMETHING TO BE SORRY FOR!!!!"

Ahem.

Anyway. back to those factors that will go into today's storms. 

One factor is sunshine. Sun heats the atmosphere, to be Captain Obvious here, and that make the air more unstable and leaves more energy for vigorous thunderstorms. We don't know exactly how much clearing we'll get so we'll have to wait and see. As of 8 a.m. today, the clouds were pretty thick across Vermont. It's a wait and see game to determine whether it will clear out at all. 

Early guesses are the best shot of any clearing later this morning and afternoon is along and south of Route 4, which  is one reason why the better chance of strong storms is down in that neck of the woods.

Also, high clouds blowing off the existing storms early this morning in the Great Lakes could race eastward, covering our neck of the woods and maybe suppressing the chances of strong storms. That's another wait and see situation right there. 

Another factor is timing. The models try to develop showers and storms in northern New York early this afternoon. Some of those models bring the shower and storms into Vermont early to mid-afternoon. If that happens, they won't have as much time to develop and won't necessarily be as strong. 

Other models bring the storms in late this afternoon, when they're more likely to be stronger. To complicate things further, the storms might or might not come through in one line. There might be several short lines of storms in various places, or clusters of them, or even isolated ones here and there. 

Upper level winds are stronger north.  If the winds are stronger up above, storms have a better shot of bringing those strong winds down to the surface. So, things aren't lining up perfectly. The best instability is south, but the best winds for strong thunderstorms are north. 

It still does look like upper level winds in southern Vermont are sufficiently strong to at least create seen risk of damaging thunderstorms. 

Here's something else I have to throw in: We have a sort of east to west weather front draped over Vermont or at least nearby in extreme southern Quebec today. You really have to watch weather fronts that are oriented that way. Especially in the spring. You get surprises sometimes from these lazy, sneaky fronts making their fainting couch the Canadian border. 

We'll see a large temperature contrast today in Vermont because of that front. Up along the Canadian border, forecast highs are around 60 degrees. That goes up to 70 by the time you get to Montpelier, low 70s in Rutland and upper 70s in Brattleboro.

The temperature contract could help strengthen storms. At least the ones in the warmer air to the south.

That front also makes it slightly possible we might get one or two storms to start rotating, maybe creating a sort of mini-supercell or two.  I know we equate spinning storms with tornadoes. And there actually is a very low, but not zero chance of a brief spinup today.  Even if a storm is spinning but does not produce a twister, it would tend to be more severe than one that is not spinning

Finally, you might have questions about flooding. Rivers are running sort of high. The ground is pretty squishy, especially where the frost hasn't entirely thawed from the soil yet. Northern Vermont in particular has gotten some rain in the past couple days. 

That will have people asking about flooding. I think we're good in that regard. It's true that some of these storms - if they do come into the state - will pack some pretty torrential downpours. A couple of these downpours might even get a couple small streams out of their banks or erode the edged so some gravel roads. Especially since the soil is so soft this time of year. 

The storms - again if they develop - will be moving right along, so torrential rain won't last long in any one place. Which really reduces the chances of flooding. In general, most of us would receive a safe half inch or so of rain today, give or take. Places that get really bullseyed by more than one storm could get up0 to an inch. 

However, so far at least, it looks like we won't have any real problems with that. But the very low but not zero flooding risk is another reason to pay attention to today's "nowcast" weather updates. 

REST OF THE WEEK

The unsettled, mild to warm weather will continue into the weekend, but we have big changes coming after that. 

Making it seem like summer, showers and possible thunderstorms - most likely in the afternoons and evenings - are a good bet each day Wednesday through Friday. No word yet on whether any of those storms will be strong. It's another thing we'll need to wait for details on.

A strong cold front Sunday will knock us back down to early spring reality.  Forecasts call for highs in the 40s by next Monday.  

Early Summer Heat At Start Of Transition To (Needed) Vermont Rainy Spell

Early morning thunderstorms, somewhat of a surprise,
approaching St. Albans, Vermont around 6:30 this morning. 

 One thing I love about summer weather is, when it gets warm or hot enough, a few hit or miss showers or storms are almost inevitable. 

Yesterday marked the first hint of our coming transition to wetter weather here in Vermont. Today will drop a few more widely scattered hints, while we'll really notice the rain Thursday. 

The vast majority of us stayed dry Tuesday. Most of us will avoid rain today. 

Temperatures Tuesday rose well into the 80s across Vermont's valleys, even touching 90 degrees in Burlington Despite some pretty dry air, a couple isolated showers and storms formed over the mountains. The slopes helped initiate updrafts which grew enough to become slow moving, isolated showers  and storms. 

I saw one on radar over southeast Vermont that seemed to be moving so slowly that I imagine one or two towns bulleyed by this might have had an inch or two of rain while places literally a couple miles down the road saw nothing. 

When there's summer warmth, any little disturbance has the potential to prompt a couple of showers. Early this morning, a real wimp of a wrinkle in the air flow overhead and a small pool of moisture in the atmosphere were enough to fire up a few widely scattered storms this morning. 

As of 7 a.m., showers and thunderstorms were mostly focused over the central and northern Champlain Valley, heading slowly east and southeast.  Which left some of us pleasantly surprised by an early morning wetting for the gardens. Other early storms were lingering  over southwestern New Hampshire. 

Any of us could see a shower or storm because of this today, though as I mentioned most of us stay dry. 

Drier air aloft will probably mix down to the surface this afternoon, which will probably limit the showers. Usually summertime storms peak at the height of afternoon heating, but today's might wane a little bit by mid to late afternoon. We shall see. 

Despite the smattering of storms around, we'll see enough sunshine to once again boost us all well into the 80s today. 

THE REAL RAIN

Thursday still looks like a wet one.  Humid, too, as the incoming cold front will draw quite a lot of moisture into our area. 

The heat of the day and updrafts along the 
mountains Tuesday produced a string of 
isolated showers and thunderstorms over
the Green Mountains and Berkshires, as
seen in this Tuesday afternoon
satellite image. 

Generally speaking, the National Weather Service in South Burlington is forecasting anywhere from a half inch to 1.2 inches of rain through Thursday night. Enough for a decent wetting.

A few spots might get nailed with a slow moving downpour or a string of them, leading to a few isolated spots seeing more than two inches of rain.

NOAA's Weather Prediction Center does put Vermont in a marginal risk zone for flash flooding, the lowest of four risk levels. They're concerned about repeated downpours along the same area near a warm front that will stall somewhere near or over Vermont for a time. 

That said, we had that long dry spell, so it would take a LOT of rain to create any local flash floods. Most of us have gone at least a week without rain. There's been lots of sun and humidity has been low until now. Things have dried out nicely. 

If there is any flash flooding Thursday and Thursday night, and that's a fairly big if, I imagine it will be very localized and probably not that bad. Still, if by chance you do encounter water over a roadway, don't drive through it. Turn around, because you won't know how deep the water is, or whether or not there actually is a road under the way. It could have washed away for all you know. 

The showers will continue on Friday through at least Sunday.  None of those days will be washouts, but there will always be the risk of getting a quick dose of rain. You never know when that rain will hit, but it'll probably be most likely during the afternoons and evenings. 

Although it will be much less warm over the weekend than it's been, highs near 70 and lows in the 50s would be just a slight touch cooler than average. No biggie.