Flash Flood In A Drought? Happens Often, Actually. Even Here In Vermont

Flash flooding in Burlington, Vermont back in 2012. Very localized
flash flooding can occur even during very dry conditions,
if the downpour is torrential enough. 

I've been whining since at least May about how dry it is here in Vermont and surrounding areas.

Despite a bit of recent rain, the southern half of Vermont is in a moderate drought, while the northern half is abnormally dry, not quite a drought, according to the most recent U.S. Drought Monitor. 

So why does the subject of flash flooding keeping popping up during this weather regime?

The reason: Tis the season for local downpours. It's the summer doldrums, when the humidity is highest and scattered thunderstorms often move very slowly, or sometimes not at all.

The best way to end a drought or a dry spell is to get an area wide, steady, soaking rain.  A torrential downpour will mostly just run off.

We've seen that a few times already this summer in Vermont.  The more intense thunderstorm rains can overwhelm the drainage in a particular area pretty quickly.  Plus, if the thunderstorm parks itself over a particular spot for an hour or two instead of moving on as usual, the rain can get pretty extreme.

We saw some flash flooding around Starksboro in late June from a stalled thunderstorm while surrounding towns remained dry.  I spotted some minor flash flooding in downtown St. Albans during last week's thunderstorms.  A flash flood warning went up very early Sunday morning for a small area of the Adirondacks due to a pocket of heavy rains.

You'll get a situation where it  rains so hard and so fast in one town that there's washouts and high water on small streams.  Meanwhile, two towns away, people are watering their dusty, wilting gardens.

The reason I bring all this up today is that, interestingly, the National Weather Service's daily Excessive Rain Outlook puts almost all of Vermont and New Hampshire, northern New York, western Maine and central New England in a slight risk zone for flash flooding over the next 24 hours.

A slight risk zone means there's a 10 to 20 percent chance of rainfall heavy enough to trigger flash flooding within 25 miles of any point within the slight risk zone.

These risk levels are akin to severe thunderstorm risks. Both are a five point scale going from marginal, to slight, to elevated, to moderate to high risk. So Vermont is at level two of a five point scale later today and tonight.

As the slight risk implies, there might well be no flash flooding. Based on current forecasts, there might be a few areas in Vermont that actually get  no rain at all between now and tomorrow.

Most of us will see some showers and storms as an upper level disturbance moves slowly into the region.  Moisture will feed into this from the southeast, forecasters are telling us. Also, an upper level disturbance consists of a pool of colder air aloft, so the temperature contrast will increase between ground level and several thousand feet above of us. That encourages showers to form.

If any locally torrential rains develop at all, I bet any instances of that would be isolated at most. The forward motion of the showers and storms will be slow, which is why there's that slight risk guidance on flash floods.

While the the National Weather Service's  U.S. level guidance has that slight risk of a pocket or two of flash flooding around here, the local office of the National Weather Service in South Burlington is less bullish with the idea.

The local office definitely has showers and a few isolated thunderstorms in the forecast today thruogh Tuesday, there's no mention of torrential rains. The South Burlington office of the NWS in this morning's forecast discussion correctly describes the expected showers as beneficial, as we definitely need the rain.

The bottom line: Most of us should see some rains in the next 24 hours that won't amount to anything too spectacular.  There's a low risk somebody could get unlucky with too much water.

Storm Threat Continues Today, Saturday For Some Of Us

Stormy skies over Lake Champlain last month. Similar
 scenes are possible today and Saturday.

As expected, scattered thunderstorms kept bubbling up, dying and bubbling back up on Thursday, thanks to an ample supply of humidity and instability in the atmosphere.

I don't have much in the way of severe weather reports, but there were a few flash flood warnings issued amid the slow moving storms, especially in the Adirondacks and southern Vermont.

No widespread damage was reported, but I'm sure people in a few spots are dealing with eroded driveways and such.

It's rinse and repeat today.

The forecast philosphy hasn't changed. Most of today across Vermont will pretty much be a carbon copy of Thursday, except it might be a little breezier and the storms might - might be a little more widespread than yesterday's.

Again, they'll start to develop in the mountains around noon and continue to bubble and die and be reborn all afternoon and into the evening.

Once again, the vast majority of us won't get any severe weather or flooding, and some of us will get no rain at all. But a few pockets across New York, Vermont, New Hampshire will get local damaging wind gusts and flash flooding.

A stronger batch of storms will start to enter New York's St. Lawrence Valley this evening, and some of those will be accompanied by damaging winds. But the storms will weaken as the sun sets. By the time the line reaches Vermont later tonight, there might be some gusty winds and heavy downpours, but that's about it.

On Saturday, the timing of the cold front is still thought to be such that the best chances of damaging storms would from central Vermont eastward

As the cold front comes across New York state in the morning, the National Weather Service in South Burlington, Vermont is thinking thunderstorms could get going in the eastern Adirondacks in the late morning and then head east.

By the time these thunderstorms march east into the Champlain Valley and especially into central Vermont just ahead of the cold front, some will get strong, with a risk of gusty winds and hail once again. This stuff will then head off into New Hampshire and Maine toward evening, and we'll be done with this relatively active weather.

Expect a coolish and nice Sunday, by the way.

Storm Threat In Vermont, Rest Of Northeast Through Thursday

Screen grab from a WCVB report on Wednesday's
 flooding in Boston. Scattered severe storms and pockets
of flash flooding could occur again anywhere in New
England today through Saturday. 

Wednesday was a gorgeous summer day in Vermont and other parts of New England - unless it wasn't.  

We entered a weather pattern on Monday in which the weather is generally good, but some areas get some big thunderstorms.

One town gets drenched and blasted by a big thunderstorm. Meanwhile, two towns over, it's wall-to-wall sunshine. It's definitely hit and miss season.

This pattern intensified Wednesday, and will continue to do so today and Friday and Saturday, too.  Which means some of us will get a very nasty thunderstorm or two, and other areas will stay dry.

It will eventually rain everywhere during this period, but some of us will only get a little rain, while others will be at risk of flash flooding. You can't tell much more than an hour or two in advance who gets what.

But at least we can give you the general scenario.

Wednesday, the worst of the storms were concentrated in southern New England, the Hudson Valley of New York below Albany and to a lesser extent, the western Adirondacks.

In this weather pattern, storms develop, intensify super fast, then die out. They're also slow movers, so you get torrential downpours and flash flooding. All of these storms also have the potential for damaging winds and large hail.

The storms Wednesday, and the ones expected today and tomorrow, also tend to contain a LOT of dangerous cloud to ground lightning.

One such storm lingered over the Boston, Massachusetts area Wednesday afternoon, causing all kinds of problems with flash flooding, downed trees, lightning strikes and fires.

The Logan Airport arrival tunnel had two feet of water in it, with cars stuck. Other roads in and around Boston had as much as three feet of water on them. The Boston Globe said the Dorchester section of Boston was particularly hard hit, with about 3.5 inches of rain pouring down there in a very short time.

Now there's today, and the weather situation is almost identical to Wednesday.  Chances are thaaat different spots will be hardest hit than those that got it Wednesday. That's just the randomness of where the storms get going.

My guess is the thunderstorms are most likely over the Adirondacks, and probably over the Green Mountains. But a gusher could pop up anywhere, at anytime between noon and sunset today.

By noon, we in Vermont and elsewhere in New England will see those towering clouds that are the hallmark of developing storms. Just like yesterday, some of these storms will grow tall and strong, and move very slowly.

Whoever gets under any one of these storms will see quite a bit of weather drama, while maybe three miles up the road, they might hear a low rumble of thunder and that's it. Again, it's the hit and miss nature of the season.

Keep an eye to the sky, and seek shelter if it looks like a storm is looming. I'm pretty sure a few isolated pockets of Vermont, and most of the rest of the Northeast for that matter, will have some thunderstorm wind damage, and some local flash flooding. Most of us will escape that. A few will not.

Just like last night, the storms will die down tonight after sunset. The heat of the sun is a large part of the fuel for these storms, so when the heat source goes away, so do the storms.

Friday, it's rinse and repeat, with maybe a few changes. It'll still be very warm and humid, and by early afternoon, scattered storms will again erupt. They'll again hit some areas, and avoid others.

However, by late afternoon and evening, a weather front will be approaching northwestern New York, which could organize storms into strong lines containing severe winds and hail.

However, that'll come in toward sunset, and some of the storms' power will ease as they approach Vermont. Showers and storms could come through any time Friday night, but they are unlikely to be severe.

Saturday, the cold front finally comes in. What kinds of storms we get all depends on the timing of that front.

If the cold front comes through in the morning, before the peak heating of the day, there will just be some showers, a few downpours, and a couple rumbles of thunder.

If the cold front holds off until later, we could get some interesting severe thunderstorms Saturday afternoon.

The cold front is coming from the west. Since tit will go through later the more east you go, at this point I think the best chance of severe storms Saturday will be in eastern Vermont, New Hampshire, Maine and eastern Massachusetts.

Again, the big caveat: If the cold front speeds up or slows down, that forecast will definitely change.

Bottom line: Just be prepared to take shelter from a potentially strong thunderstorm anytime between now and Saturday evening.

A Break Today, Then More Storms. Floods, Too?

A storm over Lake Champlain Tuesday afternoon, as
seen from Overlook Park in South Burlington, Vermont

Just a quick update before I go outside and enjoy and (mostly) rain-free day.

As expected a lot more showers and storms swept across Vermont and most of the rest of the Northeast on Tuesday.  

Some storms did end up dropping quite a bit of hail, again as expected.

The worst problem, going forward, is that the storms on Tuesday added yet more moisture to the ground. And a lot more rain is looming. We could be looking at another flood potential over the weekend.

What looks to be a very wet warm front - probably similar to the one that brought us a soaking last Friday, looks to hit us on Thursday, especially in the afternoon and evening.

There won't be a lot of thunderstorms with it, but it looks like another soaker - possibly an inch of rain that will really turn the ground to a swampy soup.

Thursday's rains don't look like they'll be enough to cause any significant flooding, but they could prime the pump for the weekend.

We'll get back into the warm, very humid air Friday and Saturday, and that sets the stage for yet another flash flood threat in Vermont and the rest of the North Country.

At this point, it sort of looks like the storms Friday will be scattered - probably not enough to trigger flash flooding, though a local torrential downpour has the potential to cause trouble then.

The trouble - if any - looks like it would come on Saturday, especially the afternoon and night. By then, it will be ridiculously humid again, with dewpoints near the awful 70 degrees.

A slow moving cold front will be approaching from the west Saturday. It looks like we could get into "training" thunderstorms again, as the air flow will be parallel to the front. That means repeated thunderstorms could keep going over the same spot again and again.

That would trigger the flash floods. Especially since the ground is so sopping wet.

This scenario for Saturday is not set in stone. A lot can happen to the weather patterns between now and then. Maybe the heaviest rain will orient itself somewhere else, like to our west, north or south.

Or, atmospheric conditions might not be ripe enough to trigger lots of torrential thunderstorms. Maybe we'll get away with just scattered stuff.

The only reason for this post, then, is to give you a heads up that there could be flash flood trouble on Saturday. Watch for future posts and updates,  and whether any flash flood watches or alerts are issued.

Also pay attention as the weekend approaches to the National Weather Service and/or trusted weather forecasting sources.

Stupid People Keep On Driving Into Floods, Keep Getting Stuck

Cars stranded in street flooding in the
Wichita, Kansas area Monday. Photo from KAKE.com 

This is the summer of flash flooding, apparently.

I've noted this already in previous posts, but yet again, a vast part of the nation is under threat of flash floods today, and many areas experienced such deluges Monday.

Today, the flash flood risk zones include a broad stripe from Texas through Oklahoma into Missouri; part of Nevada and the desert Southwest, as monsoon moisture will trigger local torrential thunderstorms; parts of Wyoming, and mountainous West Virginia, where gullywashers could easily sweep down steep slopes today.

This just adds to epic rainfall totals for the year in some parts of the nation, a contrast to the West Coast, where the drought just keeps on grinding on.

The flash floods this week add more to the usual phenonenon we see: So many people driving into flooded streets, and getting stuck.

I guess the National Weather Service's constant refrain, "Turn Around, Don't Drown," isn't working. I don't know why.  It seems pretty easy to understand, at least to my little brain.

I'm amazed at the videos, an example of which you see below, of people seeing that cars and trucks have died out as motorists tried to drive down flooded streets. But does everybody else turn around?

Of course not! Some people soldier on, thinking they have magical powers in which everybody else's car drowns in the water but theirs won't.

In the videos, you do see other people turning around instead of plunging into the water. You can almost see the thought bubble of the people in the cars that are turning around. They look at people with their stuck cars and say, "Loser."

The video below, from StormChasingVideo.com, shows cars struggling amid flash floods in Wichita, Kansas Monday.

Wichita isn't exactly a remote, boony one road town. A little under 400,000 people live there. It's a pretty sizeable town.  You'd think that if one street floods, you can turn around and find a nearby street that's not flooded and do a detour there.

So, if you encounter flooding today, no matter where you are, don't drive through it. The car and life you save might be your own.