Sunday Tornado Weather and Isaias Looms

It's been a pretty exciting summer in the weather department, what with record heat, storms and, I don't know, locusts next?  

Likely tornado near Sharon, Connecticut
on Sunday. 

There was a bonafide tornado threat in Vermont Sunday, though none materialized due to a stroke of luck with timing, which I'll get into in a bit here. 

It also seems that Tropical Storm Isaias will have a very noticeable impact on Vermont Tuesday and Wednesday.

SUNDAY'S STORMS

Western Vermont was under a tornado watch Sunday afternoon and evening.  It's rare that parts of the Green Mountain State "earn" a tornado watch twice in one year, but we've done it.  The other watch was in May, but no tornadoes hit the state then. 

Sunday's tornado watches extended through eastern New York, southwestern New England and Ontario Canada. There was at least one possible tornado near Ottawa.  A confirmed tornado touched down in the western Massachusetts town of Blandford.  Also, judging from radar images, and photos and videos on social media, there was at least one other tornado in northwestern Connecticut and possibly adjacent New York State. 

The National Weather Service in South Burlington issued a couple tornado warnings for a rotating storm in the Adirondacks last evening.

Here's the timing issue that helped save Vermont from worse problems with storms Sunday evening.  You might have noticed in yesterday's post that I said there would need to be a good deal of sunshine to help destabilize the atmosphere. 

A warm front kept clouds in most of the state until late afternoon and evening. It did get quite clear for awhile early in the evening, but that was too late to really get things going.  By the time those rotating thunderstorms spun up west of here, the sun was setting. So the storms weakened by the time they reached Vermont. 

Still, those Adirondack storms dumped 1.31 inches of rain on Burlington just before midnight last night, including 1.18 inches in just an hour.  This was that city's wettest day since last Halloween. Thunderstorms also cut power for while at my house in St. Albans, Vermont. 

Today will be quiet, but then we have Isaias

ISAIAS AND VERMONT

Early this morning, Tropical Storm Isaias was off the coast of northeast Florida with top sustained winds of 70 mph.  The storm spent the day struggling with strong upper level winds, which kept trying to shear intense thunderstorms away from the center of Isaias.  Those upper winds only partly succeeded.  

Forecasts have kept nudging the expected track of Tropical Storm Isaias westward when it will move over the Northeast later Tuesday. 

The bad news is that if the forecast holds, the track if Isaias will be somewhat similar to notorious Tropical Storm Irene, which caused such devastation in Vermont back in 2011.  The very good news is Isaias won't be nearly as bad as Irene.  That said, you should really pay attention to Vermont forecasts regarding Isaias.

 

Those upper atmospheric winds are abating a little bit this morning, and Isaias has a chance to regain status as a hurricane before reaching the North Carolina coast early tomorrow morning. 

Whether Isaias ends up being a high end tropical storm or low end hurricane doesn't matter a whit in the grand scheme of things. It'll spread storm surges, tropical storm force winds and flooding rains all the way into New England. 

It's not every day you see a tropical storm watch for places like northern New Hampshire and interior western Maine. But there you have it. It's 2020. Honestly, this year, everything should be on your Bingo card and this is one of them. 

This looks like one of those snowstorm forecast
maps I post in the winter, but don't worry. It ain't going to 
snow. This is one forecast for possible rainfall from
Tropical Storm Isaias. 1.5 to 3.5 inches of
rain are expected in Vermont, with a few
spots going over four inches in the southeast

Flash flood watches for Isaias extend from South Carolina all the way northward to Vermont's Canadian border. 

Because of its more westward expected track through central New England, the National Weather Service offices in South Burlington and Albany have issued a flash flood watches for all of Vermont except Grand Isle County.

The potential flood trouble looks like it will come from the rainfall rates associated with Isaias and not so much the amount.  

Rain will overspread Vermont well ahead of Isaias south to north starting early Tuesday morning.  When the actual storm blows through Tuesday night, rainfall rates might be as high as 1.5 inches per hour.  

That's enough to possibly cause urban, small street and creek flooding, along with washouts on steep roads, culvert collapses and such. 

Because it's been pretty dry this summer and Isaias will blow through New England really fast, it won't rain for a long enough period of time for the state's larger rivers to flood.  Water levels in those rivers will come up, but probably not enough to cause serious flooding. 

Still, there will be a lot of rain, which is actually also helpful as well as threatening. (We need rain, still).  Overall 1.5 to three inches of rain could come down across Vermont, with local amounts of four inches or a little more in the south. 

Do note the flash flood threat will peak after dark on Tuesday.  If you're on the roads, it's harder to see flooding, so you might not be able to brake in time to avoid a flooded spot or washout.  You're better off just staying home Tuesday night. 

Wind will be a bit of a problem with Isaias in Vermont, too.  Southeastern Vermont and the western slopes of the Green Mountains could easily see gusts to 45 mph, so there might be trouble with power outages here and there. 

After Isaias is out of our hair, it's back to dry and warm weather again for the second half of the week and into the weekend