Monday, July 28, 2014

Sunday's Storms In Vermont Created Amazing, Sometimes Rare Clouds

Many thunderstorms, some of them severe, raked Vermont and parts of northern New York Sunday.
A roll cloud precedes a weakening thunderstorm
approaching St. Albans, Vermont Sunday evening.  

It was part of a massive severe weather outbreak in the eastern third of the United States that produced damaging tornadoes in Tennessee, Kentucky and elsewhere, wind damage, hail and flooding.

There were 378 reports of severe weather across the nation Sunday, including six tornadoes.

The damage wasn't so widespread here in the North Country, with reports of flash flooding near Plattsburgh, N.Y, one-inch diameter hail in Ferrisburgh, Mendon, Westford and Williston, Vermont, and tree damage in places like Charlotte and Peacham, Vermont.

Outbreaks of summer thunderstorms often create the most interesting clouds imaginable, and Sunday's bout of storms did not disappoint.

I was treated with the rare sight of a well developed roll cloud preceding a non-severe thunderstorm rolling toward my home in St. Albans, Vermont.

The roll cloud in St. Albans, Vermont Sunday evening
scrapes against a low hill as it crosses the community.  
Later, the setting sun, lit up some mammatus clouds, a relatively rare sight in the Green Mountain State, and a sign somebody off to my east or northeast was getting a really nasty storm.

I also saw some shelf clouds yesterday, too.

I'd better explain my terminology.

A shelf cloud looks like just that, a low, dark, shelf like feature in the front of a thunderstorm.

When you see a shelf cloud, it's time to take cover, because the parent thunderstorm is probably severe. When the shelf cloud goes overhead, you're likely to get  really nasty burst of strong, damaging winds and maybe some hail.

You'll see just after the middle of a time lapse video a shelf cloud Sunday evening over Malletts Bay, Colchester, Vermont.

Mammatus clouds are lit up by the setting sun
over St. Albans, Vermont Sunday evening.  
A roll cloud like the one I saw yesterday looks dramatic and scary to people unfamiliar with them, but they really aren't dangerous at all.  

They're usually caused by a downdraft from a decaying thunderstorm that lifts a bit of warm and humid air from the surface.

The air rises and curls toward the dying thunderstorm, and you get something that resembles maybe a weird, horizontal tornado.

When the roll cloud moved overhead in St. Albans, we had a wind gust to perhaps 20 mph, followed by a brief burst of rain. Nothing scary.

The decaying thunderstorm that caused my roll cloud was ceding energy to a strengthening thunderstorm to my south, near and to the northeast of Burlington, Vermont.

Another view of the mammatus clouds over
St. Albans, Vermont Sunday evening.  
That storm complex continued toward the northeast. When it got to near St. Johnsbury, in northeastern Vermont, it had become quite strong and was producing a few damaging wind gusts and probably some hail.

As the sun was setting, it lit up the anvil shaped top of the thunderstorm, way up there maybe at 30,000 feet above sea level.

The anvil top curved back many miles toward the west, as they often do in strong storms. The top of this thunderstorm was easily visible from my house in St. Albans, 50 west of the storm's core.

The anvil top of a thunderstorm consists of moisture that spreads out as its upward momentum dies off.

Developing thunderstorms early Sunday afternoon made
for a pretty sky over Lake Champlain near South Hero, Vermont.  
Sometimes, some of the ice in the air within this anvil starts to sink, giving you those pouches that you see in mammatus clouds.

Mammatus clouds are always connected to thunderstorms, and the thunderstorms they're connected to are often, but not always strong or severe.

But if you see mammatus clouds overhead, like I did Sunday evening, don't worry. Usually, they're on the back side of a storm, which has already gone by.

Of course, days with thunderstorms create more routine, but very pretty and interesting cloud patterns.

It was fun to watch thunderheads bubble up to become storms during the course of the afternoon. They you could see big blasts of rain come out of the storms, then a rainbow to finish it off.
A thunderstorm dumps a heavy load of rain in this
view from Lake Champlain looking toward Colchester
and Burlington, Vermont.  

Very pretty.

Today, there's more storminess in Vermont and New England.

There could be some interesting clouds again amid the possibly strong storms in eastern Vermont, New Hampshire and Maine.

But places more to the west will likely see rain and a dull overcast. Not nearly as interesting as Sunday.

Here's that time lapse, produced by Dan Russell, of thunderstorms in Malletts Bay, Colchester, Vermont to give you another glimpse of Sunday's stormy, changeable and fascinating skies:

No comments:

Post a Comment