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| Thunderstorms briefly tried to develop to the northwest of Burlington, Vermont during the peak heating of the day Saturday, when temperatures were in the low 90s. However, warm air aloft reasserted itself, and the wannabe storms quickly died out. |
Also, although expected storms eventually developed across northern Vermont last night, they proved to be a forecast challenge, and computer forecasting models really botched the job. I'll get into that later and explain what went wrong and what went right.
First the heat:
DANGER DANGER
Yesterday, the National Weather Service in South Burlington, Vermont issued an Excessive Heat Warning for the Champlain Valley, Rutland County, and the St. Lawrence River valley of New York. This morning, that warning extended to parts of the Connecticut River valley.
This is the first time in the National Weather Service history that an excessive heat warning has been issued in Vermont. Less dire heat advisories are issued from time to time, but not this.
The excessive heat warning is a good move, and one you should take very, very seriously. With afternoon temperatures both today and Monday in the mid to upper 90s and dew points above 70 degrees, the heat index - how the hot weather actually feels - will be as high as 110 degrees.
That's downright dangerous. I saw a nutcase jogging yesterday in Burlington while the heat index was 97 degrees, which is crazy. Whatever you do, don't be that guy today. Stay in a cool place, and abandon any idea of any heavy physical activity outdoors.
On Saturday, it reached a high of 93 degrees in Burlington, enough to tie the record for the date. Record highs are certainly in jeopardy today. The record high today is 96 degrees in Burlington; the forecast high is 97. On Monday, the record high is also 96; the forecast high is 99 or 100.
Yep, there's still a chance that Burlington could reach 100 degrees today or more likely tomorrow. That has only happened four times since at least the late 1880s.
As I've noted before, the longer a heat wave goes on, and the more consecutive hot, muggy nights we have, the greater the toll on the body. So pace yourself, and find any excuse you can to find air conditioned space. Do it now, and do it frequently, so you don't wear out. This is true especially if you're elderly or not in great health to begin with.
I'm healthy, but I volunteered today to pick up an extra shift at one of my jobs, something I never do on Sundays. But the place is air conditioned. Yeah, I could use the extra money, but I'm really after the air conditioning. Gotta stay on top of this.
The heat wave, as we've already noted, will grind on most of the upcoming week. By Wednesday or Thursday, it will be "colder." with highs "only" near or just above 90 degrees. Still very yucky and dangerous.
On Friday, a glorious, glorious cold front will make an approach. It could set off severe thunderstorms, but it will be worth it. Behind the cold front, the National Weather Service is now saying next Saturday will be sunny, with low humidity, and the high temperature will be a bone-chilling 77 degrees.
So that's something to look forward to.
BOTCHED STORM FORECAST
Early Saturday afternoon, it was looking more and more like there would be a lot of thunderstorms across northern New York and northern Vermont by around 6 p.m. or so. And of course, nada. The radar screens were pretty much free of storms as we went into the evening Saturday.
This despite NOAA's Storm Prediction Center saying we had an enhanced risk of storms. And all other forecasters were saying the same thing. I had absolutely no reason to doubt those meteorologists. It looked like a great set up for at least a few severe storms. Including the possibility of a bowing echo - which is a particularly nasty line of damaging thunderstorms.
Storms did develop explosively just after sunset in Quebec and moved south into New York, Vermont and New Hampshire, but they formed much later than expected, and were not as extensive as earlier forecasts.
What went wrong with the forecast?
Two competing weather systems - one that encourages thunderstorms, one that discourages them were battling it out right here over Vermont.
The weather that would encourage thunderstorms was a disturbance coming in from the northwest -- crossing Ontario and southern Quebec. The disturbance would add lift to the atmosphere. The updrafts would interact with the heat and humidity to produce a sudden burst of thunderstorms.
Or so we thought.
The heat wave we're engulfed in now was still building in, too. The high pressure system that is causing this heat wave features sinking air, which discourages thunderstorms. Also, not only is it hot here, it's warm many thousands of feet in the air over the top of this heat wave, too.
Since the air isn't cooling all that much with height, thunderstorms have a hard time blossoming. They need colder air above to flourish. There is cold air above the warm layer up above us, but wannabe storms couldn't push through that warm air.
Forecasters generally thought the disturbance from Canada would win out on Saturday and thunderstorms would get going. During the mid afternoon, a few clouds managed to break through the "cap" of warm air above. They accessed the cold air higher up and some isolated, strong thunderstorms formed.
But then the cap of warm air above reasserted itself, and things very quickly quieted down. The hot high pressure system and its warm air continued to prevent thunderstorms, despite the persistence of computer forecasting models that kept insisting that thunderstorms would blossom around 5 p.m. - no wait, maybe 6 p.m. -- Or 7 p.m.. You get the idea.
The short range computer models were not working nearly as well as they normally do when forecasting weather that is just hours away.
Just when meteorologists were ready to completely give up on the computer models and their seemingly false forecasts of strong thunderstorms, the storms finally did erupt in southern Quebec shortly after sunset.
They weren't as widespread as first predicted, but they did get strong fast. Remarkably, for the second time in a month, a tornado warning was issued for northern New Hampshire's White Mountains as some of the storms began to rotate. (So far, there are no reports of a tornado actually touching down in New Hampshire last night.)
Some of the storms that entered northern Vermont from Quebec appeared to have some rotation to them at times, but not enough to create any major tornado fears. The storms came late 10 p.m. to 2 a.m., so people weren't up to report much damage.
The only Vermont report I've seen of storm damage from last night was of trees down at Lake Carmi State Park. I watched the storm that caused the Lake Carmi damage pass by to my north and east of St. Albans. Boy, there was a lot of lightning! Despite my 20 mile or so distance from the storm, it still managed to push a gust front with winds of about 30 mph through my neighborhood.
I've also gotten some reports of strong winds in St. Johnsbury from a severe-warned storm overnight. Quarter sized hail was reported from the tornado-warned storm near Berlin, New Hampshire.
In Barton, Vermont, heavy rain from a late thunderstorm caused water to pool on Interstate 91. A car driven by a person police said was intoxicated and speeding hit that water and crashed, killing one person.
When it's as hot as it is today and will be tomorrow, there's always enough energy in the atmosphere for thunderstorms to develop explosively and become strong very fast. However, with the heat wave now in full tilt, the dome of hot air over us, it will be very hard to get a thunderstorm going.
Very few, if any of us will get a thunderstorm today and tomorrow. It's possible updrafts near mountains will initiate a few isolated storms today and Monday. If any of those develop, they'll become strong to severe within minutes, then die out to nothing just as quickly.
Later in the week, there might be more opportunities for widely scattered afternoon and evening storms to form during the heat. Finally, that cold front I mentioned will create more storms, and a welcome break from this extreme heat wave.
I watched from Barre it was quite a show even from here.
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