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| For now, forecasters are maintaining a slight risk of flash flooding tomorrow and tomorrow night over our region. That means a 15 to 40 percent chance of enough rain within 25 miles of a given point to cause flash flooding. Those forecasters are considering an upgrade to moderate risk in parts of this region, but are holding off due to lingering questions as to where the heaviest rain will set up. |
The computer forecasting models, however, are still not being super helpful as to where the greatest risk might fall.
The National Weather Service office in South Burlington notes there's still not a lot of agreement among the computer models as to where the heaviest and the biggest flood potential will set up.
One group of computer models tells us the best chance of potential torrents of rain and flooding would be along and north of Route 2. The other group of models takes the torrents mostly through southern Vermont.
Overall, we should still expect trouble somewhere in Vermont. Wednesday's anniversary of last year's big flood will unfortunately probably bring another round of flooding. Like we need it.
Thankfully, though it could be a dangerous situation tomorrow, this won't be quite as bad or as widespread as July 10, 2023.
You still need to pay attention to all this through Thursday though. If you're looking for specifics as to who's most at risk, you'll need to wait until tomorrow. Also note the word "flash" in "flash flood". You get very little if any notice when such a flood develops which is all the more reason to stay on your toes.
No flood watches have been issued just yet. I think that might happen later today or tonight when we have more forecast clarity.
THE SPECIFICS
Monday was another very warm one, but it was nice if you like hot weather. Burlington reached 90 degrees again, making it already the eighth day this year at or above 90 degrees. Humidity was moderate, and there was a lot of sun.
We had a good beach day.
Today
We'll feel worse than yesterday today, and a couple weather risks have been introduced into the mix. Temperatures will be just as warm as yesterday, with widespread 80s and a few places touching 90 again.
The humidity is getting worse this morning, though, and will continue to worsen through the day. The dew point - a rough measure of how sticky it feels out there - will be near 70, which is oppressive.
That's hot enough to trigger a heat advisory in parts of the Champlain Valley. Elsewhere in the state, it will still be dangerous to overexert yourself outdoors. People with health issues should seek air conditioning if the can.
All this humidity hanging around today will trigger scattered thunderstorms in the afternoon and early evening. Most of us will either get nothing or something relatively tame. But some storms will have torrential rains, so we start to get a risk of isolated spots of flash flooding.
That's a foretaste of what to expect tomorrow.
Wednesday
Here's where the remains of Hurricane Beryl enter the picture. The already sopping wet and sticky air over us will get an infusion of extra water that could dangerously dump on us.
The breakdown of the two main forecast scenarios goes as follows:
In the first scenario, a west-to-east boundary, sort of a semi warm front would hang around central and northern Vermont. That would encourage those "training" downpours and thunderstorms. The boxcars going along the railroad tracks I keep talking about.
That would quickly put those areas in the northern third of Vermont under the gun for flash flooding starting in the afternoon and continuing well into the night.
Pockets of southern Vermont would get some local flash flooding in thunderstorms, too. Also, you always have to be careful of thunderstorms just south of warm fronts like we'll have tomorrow. Storms just to the south of such fronts tend to rotate. There's a very, very low but not zero chance of a brief tornado under this scenario. There's be a slightly greater chance of a couple storms having damaging straight line winds.
Under the second forecast scenario, our warm front sets up a little further south, so the training, persistent downpours hit the southern half of the state. That would put the better chances of flash flooding south of places like Middlebury and Barre/Montpelier.
Northern Vermont would not be out of the woods in this set up. The air will be so humid it will support torrential downpours even there.
The consensus at the moment is that most of us should see one to three inches of rain. Somewhere in our region, there's a great chance of a band of two to four inch totals, with spots within that band seeing five inches or even more of rain.
Much of that rain would come down within a few hours. As it stands now, most of Vermont would need roughly 1.8 to 2.5 inches of rain within three hours to trigger flash flooding. Or two to three inches within six hours in northern Vermont to do the same. We could easily see that much rain.
Chances are some spots will see more than enough downpours to set up some dangerous flash flooding by Wednesday night. Not everywhere, mind you. But some locations.
As far as the state's larger rivers go, it's still unclear how high the water will get. Some of those rivers will probably flood, but not to the record extent they did last July. Whatever happens, water levels on the bigger rivers would peak Wednesday night and Thursday. Time will tell, and I'll have updates.
By the way. what I described above are the two likeliest scenarios. There will be variations, along with twists and turns in the forecast leading up to the event, and even during it. Who knows? Maybe the two scenarios will split the difference and focus on central Vermont.
We'll all have to stay on our toes for this one.
Thursday
Some dry air should move in aloft, even though it will stay humid down here on the ground. If that happens, thedry air up above will help, as that will limit the number of thunderstorms we get during the afternoon. There will still be a few that could produce torrential downpours to locally worsen any issues that develop Wednesday and Wednesday night.
But it shouldn't be super widespread. With some sun and intense humidity still in place, any post-flood cleanup work will be that much more dangerous. Heat exhaustion would be a real threat.
That goes for beyond Thursday as well. A wee bit drier and ever so slightly cooler air will work in Friday and maybe Saturday to spell a little relief before rather hot, humid weather returns again. Storm chances look low Friday and Saturday, but should start to increase again Sunday.
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