Nation's Flash Flood Season Is In Full Swing

A flash flood near St. Albans, Vermont in 2014.  A stalled thunderstorm
caused this one. 

Now that we are full on into summer, the peak of severe thunderstorm season has passed, but we're into what I regard as peak flash flood season.

We can and do often get severe storms and tornadoes in the United States through the summer. But big outbreaks of severe weather are now less common.  That's because there are no - or at least few - big storm systems with immense clashes of cold and hot/humid air to generate tornado barrages.

Instead, smaller weather fronts and weak low pressure areas meander sluggishly, or sometimes not move at all through much of the rest of summer.

There's usually plenty of very humid air to work with around these weak, slow moving systems. The result is torrential downpours.

If these downpours don't last super long, this is a good thing, as it keeps crops and gardens watered down, and tamps down the risk of wildfires. Often, though, you can get several inches of rain in just a couple hours. And these downpours sometimes tend to linger in one place, compounding the trouble.

Many of the culprits behind these flash floods, especially in the middle of the nation, are caused by something called Mesoscale Convective Systems, or MCS's. 

These are huge complexes of thunderstorms that regularly develop late in the day somewhere in the Plains or Midwest and continue on all night.

These things are very common in the summer and all things considered, have a lot of benefits. They keep the corn belt well watered during the critical growing season.

Some of the storms are really intense in these MCS's though. They can dump tremendous amounts of rain in a short period of time and cause almost daily pockets of flash flooding in the summer.

Yesterday, an MCS caused flash flooding east of St. Paul, Minnesota.  This morning, one is causing flash floods in Illinois. 

Other areas of flash flooding could develop today and tomorrow in parts of North Dakota, Kentucky,  and mountainous areas of Idaho and western Montana.  Flash flood risks are usually scattered in random fashion like this during the summer in the United States.

Slow moving cold or warm fronts, or stationary fronts, can also unleash flash floods. In these cases, thunderstorms move along the same path, one after another, over the same area like boxcars passing by on train tracks.

These are called training storms literally because they resemble a train moving down the tracks.

Weak low pressure systems can also cause cause flash flooding by generating showers and thunderstorms rotating over the same area. Early season tropical storms can cause similar problems.

Even areas that are drier than normal - and in drought - are prone to flash flooding this time of year. If it rains hard enough, creeks, streams and river can become overwhelmed with runoff, as can city streets where the storm drains can't handle the deluge.

Most of Vermont is now in drought or at least abnormally dry.  But an area of thunderstorms prompted flood advisories in some sections of southeastern Vermont yesterday.  And there's a marginal risk - very slight - of flash flooding today in much of Vermont today and tomorrow due to the risk of slow moving storms.

As is typical with most flash floods, any risk in Vermont would be limited to very localized areas, while surrounding areas just a few miles away stay relatively dry.

Climate change is probably worsening flash floods and making them more frequent.  A warmer atmosphere can hold more water vapor.  That means more water is available for downpours when something triggers a storm, such as a stalled front or MCS.

The resulting downpours are heavier than they otherwise would be, so the flooding is worse. And more frequent.

Vermont, like many mountainous areas, is especially prone to flash floods because a stalled thunderstorm over the Green Montains can send torrents of water down the slopes, ripping away roads, bridges and sometimes houses.

Also, our small urban areas can become flash flood zones during heavy thunderstorms.  Some nasty ones have happened in Burlington in July, 2012 and in Rutland in 2009.

At least some localized flash flooding happens in Vermont almost every year. Even dry ones.

So while we pray for continued rains this dry summer, let's just hope it won't be too much of a good thing.

Australia's Weather Goes Bonkers

On top of everything else, a massive dust storm ripped through parts
 of southeastern Australia this week.  

I"m going to need to re-name this blog, "Australia Weather Rapport" since all the extremes and action, not to mention the politics of weather are happening Down Under.

Sure, those super destructive, super scary bush fires are still a threat. Summer isn't over in Australia yet.

But this week, new extreme weather decided to enter the mix. These included massive dust storms, massive hail storms and some serious flash floods.

No doubt some of the storms were extremely welcome. After all, they doused some of those fires. A win! Yet with all the damage Australia has suffered in the past couple of months, the hail, the wind, the floods, the dust, just added that much more devastation.

Who knows what will happen next in Australia? As the several dramatic videos below show, I'm sure Australians just want their awful summer of 2020 to end.

Here's an overview from The Guardian:



The Australlian Capital of Canberra was especially hard hit with hail as supercell thunderstorms rolled through. Sydney got nailed, too. Here's a News 9 report:



Not a nice day at this Canberra outdoor restaurant:



Aftermath of hail in Canberra makes it look like they were hit by a New England style winter storm:



Meanwhile, elsewhere in Australia, check out this kabob/dust storm in part of New South Wales this week: This wall of dust was reportedly was 180 miles long as it rolled over the region. When the dust storm hit the town of Dubbo, winds reached around 66 mph.

Possible Bad News With Tropical Storms Dorian, Erin

Tropical Storm Dorian east of Puerto Rico early this morning. It's
looking more organized than it did yesterday.

As expected, forecasts keep shifting for Tropical Storm Dorian, and as of now, the news is worse for Florida, which could end up taking a nasty hit.

Land interaction, which could have potentially killed Dorian if it went over Puerto Rico or especially the Dominican Republic.  

Now it looks like Tropical Storm Dorian will just clip eastern Puerto Rico before head northwest into warm, open waters, where it could strengthen. That means it won't be over land long enough to get destroyed.

Top sustained winds with Dorian this morning were up to 60 mph, and the Natonal Hurricane Center says the storm definitely looks better organized than yesterday.

Dorian is going to cause problems in Puerto Rico and the Virgin Islands today. Puerto Rico is especially vulnerable. Their electrical system is still a mess after Hurricane Maria two years ago. Tropical storm force winds will be enough to wreck the lines once again.

Even more so than yesterday, Florida had better watch out for Dorian. It will be mostly over open water as it moves northwest, then west toward Florida, as it stands now.

Very often, a tropical storm or a hurricane heading northwest near Puerto Rico will curve harmlessly out to sea. But a large high pressure system over the western Atlantic Ocean looks like it will get in the way, steering Dorian westward toward Florida.

The National Hurricane Center says computer models have Dorian strengthening into a hurricane by Friday and remaining a potentially strong hurricane as it nears the northeast Florida coast on Monday. The NHC also says the hurricane would grow larger in size with time before it hits Florida.

This of course is a preliminary forecast, and the eventual path and strength of Dorian could end up being very different from current forecasts.

But if this prediction stays on track, this would be a rare hurricane hit for northeast Florida. The coastline there sort of curves inward, and hurricanes tend to hit either further south in Florida, or up the coast in the Carolinas.  This one could be serious, and we need to keep an eye on it.

TROPICAL STORM ERIN

That tropical depression off the East Coast yesterday has strengthened into Tropical Storm Erin. It only has sustained winds of 40 mph and won't get much stronger, says the National Hurricane Center. It will also stay well off the East Coast and eventually come ashore somewhere near Nova Scotia late Thursday or early Friday.

So no problem, right?

In this case, wrong. Or at least kinda wrong. A cold front that will give us showers here in Vermont later today will keep trucking deeper into New England. That will draw tropical moisture from Erin northwestward into eastern New England.

Flash flood watches are up for eastern Maine, coastal New Hampshire, eastern and central Massachusetts and Rhode Island later today and tonight. The worst downpours will be hit and miss, but a few spots could get four or five inches of rain in a short period of time, so that's a problem.

Rainfall might be locally  heavy in southeastern Vermont, too, but it likely won't be bad enough to cause any issues.

Strong Storms, Downpours To Hit Vermont, Rest Of Northeast Today

Areas in yellow face a slight chance of severe thunderstorms today. 

When I got up early this morning skies were still clear. Did that mean the expected storminess today wasn't coming?  

No and Nope.

We should expect quite a bit of  weather today. The good news is those of us who need a good rainfall looks like we'll get it.

The bad news is in some areas, it could rain too hard and cause very local flooding problems. And some storms could turn severe in central and southern areas.

A warm front was coming at us from the southwest early this morning, and that should give most of us an initial slug of rain later this morning and early this afternoon. I say most of us because radar images early this morning did detect gaps in this area of rain, so some of us might get unlucky, again.

Early this afternoon, most of us, especially areas south of Route 2 in Vermont, will get into the warm, sticky air again. The sun might also break through the clouds, which will help destabilize the air ahead of a cold front. That sets the stage for possible strong storms.

SEVERE WEATHER DETAILS

The best chances for severe storms will be central and southern Vermont, the Hudson Valley of New York, western New Hampshire, western Massachusetts and northwestern Connecticut.

Not everybody will get severe storms in those zones. Most people won't. But a few towns very well could. The biggest threat from the potentially severe storms is strong straight line winds and microbursts.

There is a very, very remote chance of a brief tornado in this region. I kinda doubt there will be any, but this year has been strangely tornadic in New England, so you never know. High resolution forecast models do indicate the possibility of some embedded supercell thunderstorms later this afternoon and evening.

HEAVY RAIN, FLOODING?

Areas in yellow are under a slight risk of excessive rain and
possible very local flash flooding. 

The next issue is rain. Many of us should expect anywhere between a half inch and an inch and a half of rain.

That's a good thing in northern Vermont, which is still quite dry. I do worry about particularly parched far northwestern Vermont, because some of the models indicate lighter amounts of rain there.

Still, anywhere that gets a particularly torrential downpour today could see local flash flood issues. That would involve small streams and creeks in mountainous areas, and streets with poor drainage in urban areas.

Widespread flooding is unlikely.

The places with the best chances of local flooding include all of Vermont, the eastern half of New York, northwestern New Hampshire and northern Maine. Again, almost everybody in this area will escape flooding. But there might be issues in a couple spots within this area.

WILL 80 STREAK END?

The record long streak of 80 degree days looks like it will come to an end today or tomorrow in Burlington. We squeaked out another 80 on Thursday, which brings the Queen City to a record 29 days in a row with temperatures at or above 80.

If enough sun breaks through the clouds between showers today, there might be another 80 today. I give it a 50/50 shot. Saturday looks cooler, with an expected high of 77 degrees. All good or bad things, depending on your perspective, must come to an end, right?

You'd Think It Would Finally Rain In Vermont With This Humidity, But Everyone Else Getting It Instead

Showers are few and far between today in Vermont, but the showers
that do form are giving the sky the appearance of something you'd see
over a Caribbean island. Which isn't surprising, since this really
is pure tropical air. 

It's another oppressively warm, incredibly humid day here in Vermont.

Once again, I cut short outdoor work because the sun, combined with the humidity was too much for me.

I originally thought - as did many forecasters - that today would be a cloudier, more showery day than recent ones.

Especially in northern Vermont, where we still really need the rain. And I would have been willing to work outside under clouds with this humidity, without the glaring heat of the sun.

And I would have been willing to work outside in these temperatures and the sun, if the humidity were lower. Rain showers would have further cooled me off out there.

It was not to be. It seems every time northern Vermont seems finally ready to get some decent rains, something interferes.

This time, it's an upper level low stuck to our southwest. In the upper levels of the atmosphere, drier air wrapped around this low, and went south to north in a corridor that took it right across Vermont.

Sure, with this awful humidity near the surface, there's bound to be some local showers and storms. One tiny cell formed in Milton early this afternoon and traveled north right along Interstate 89 all the way to Highgate.

Meanwhile, flash flooding is so bad in Pennsylvania today that a
building housing the New Albany library sadly washed away.
Thankfully, two people in an apartment on the second floor
of the building were rescued before the structure
entirely broke apart. 

When I got home to St. Albans, Vermont early this afternoon,  things outside were wet, so at least I got a little needed rain out of the deal, while lots of other people didn't.

Most showers and storms that form the rest of this afternoon over and near Vermont will get going over the mountains and pretty much stay there. We lack any real wind in the atmosphere, so there's nothing to push them along.

Because showers and storms will be such slow movers, isolated spots in the state could get torrential downpours and gullywashers.

If any particular storm gets especially tall, there's barely enough wind in the upper atmosphere to push them into valleys. Most valley locations won't get rain the rest of the this afternoon and evening, but there's hope a few will.

The tropical air looks really, well, tropical. I swear the sky over the Green Mountain State today looks more like we're on a Caribbean island and not in northern New England.

The next chance of widespread, meaningful rain in northern Vermont will come along Friday and Saturday, but I'm guessing, just as we repeatedly experienced all summer, some complication will come along to prevent that anticipated precipitation.

Meanwhile, so many people under and close to that upper low I talked about are getting, way, way too much rain. Flash flooding has been an enormous problem since Saturday in these areas, especially in Pennsylvania and New Jersey, and that state of affairs continues this afternoon.

The flash flooding continues today, especially along the Pennsylvania/New York border near Elmira and Binghamton. It's gotten so bad a building housing a library in New Albany, Pennsylvania literally washed away in the flood.

It continues: Some people are getting way too much rain, and not that far way, other people are not getting enough. Too bad we don't have the power to redistribute it.

Another Vermont Heat Record Might Be Set Today. And WIld New Jersey Flood Vis

While summer warmth grinds on up here in Vermont,
flash flooding swept these cars away in
New Jersey Saturday.

We've set all kinds of heat records around these parts this summer and it looks like we might be about to tie, then break another one.  

If the temperature in Burlington, Vermont reaches 80 degrees today, we'll tie the record for the most consecutive days in which the temperature has reached that level.

That would be 25 days, which is how many consecutive 80s there were between July 22 and August 15, 1988.

It'll be close, but we might make it today. The forecast high today in Burlington is precisely 80 degrees. If it's a little cloudier than expected, we might not reach 80. A little extra sun would bring us above that magic number.

If we get to 80 today the streak will likely continue. The forecast high on Monday is 83 degrees. Tuesday's forecast is 81, Wednesday is 83, Thursday is 81. At this point, the forecast for Friday is 79 degrees, which would end the streak.

But we don't know that for sure.  On any of these days listed, the temperature in Burlington could easily be a few degrees below or above the forecasts. It depends on the timing of clouds, showers, and unexpected changes in the forecast for oncoming weather systems.

The upcoming weather systems in question continue to promise a humid week for us, with scattered showers and thunderstorms daily starting today and going through the week. Any showers or storms today will be widely scattered at best. Most of us won't see one. But if any develop, they will be slow movers. Whoever gets a storm might get a lot of rain from it.

At this point, the wettest day looks like it will be Tuesday. But again, some places will get little rain, some places will get drenched. It's all the roll of the dice.

This wet weather pattern really hit New Jersey and other sections of metro New York, the Mid-Atlantic states and a few places in southern New England Saturday.

Flash flood warnings were flying in different areas in the region all day. Some floods caused quite a bit of damage. Below is a video of a flash flood in Passaic, New Jersey swiping cars from an auto dealership, sending them downstream and crashing into a bridge and each other.

Northeast Floods Peak Today, But Will Northern Vermont Miss Out On Rain AGAIN?!?

Parts of Pennsylvania are under a rare high risk area (in purple) for dangerous
flash floods today. Believe it or not, parched Vermont is under
the slight risk zone for flash floods. Torrential local downpours
could cause small areas of flash flooding, despite the dry conditions. 

So far, just some piddling little light showers have come through Vermont's Champlain Valley as of 3 p.m. Wednesday as we remain parched.

Meanwhile, parts of the Northeast are under a rather rare high risk zone for life-threatening flash floods today. 

I'm so wishing for something much milder than flash floods and much more intense than sprinkles, but for me, it remains to be seen whether that will happen.

The real news, of course, is today's flash flood threat, centered in central Pennsylvania and south central New York, down by Binghamton.

In these regions, it has rained and rained and rained this week and soils are saturated. There has already been some pretty serious flooding in this region. As I write this, thunderstorms are increasing again in super soupy air over Pennsylvania, so intense downpours are developing again.

The worst of the rain in Pennsylvania looks like it is, or soon will, fall in an area that has had a foot of rain in the past week.

This will be bad, and I'm sure we'll hear of more flash flooding damage in Pennsylvania and New York.

Already, there's big trouble. The famed Hersheypark in Pennsylvania  is closed today for the second time this week due to flooding. There's not much in the way of flooding inside the park, but the roads leading to it are under water.

The nearby Knoebels Amusement Resort is under water.

The weather pattern that has stalled for the past few days, keeping most of the rain to Vermont's south and west, is on the move again. This is why forecasters are insisting we'll finally get our share of rain later today and tonight.

The chances are still there. Showers and thunderstorms are increasing to our southwest, so we might get into the action. And, what is essentially a very weak cold front is in western New York, and is slowly moving east.

This, you would think, would be the focus of a pretty good band of rain coming through Vermont just ahead of this so-called cold front. Chances of that rain happening this evening are pretty damn good. Forecaster are insisting we will have somewhere around an inch of rain by Thursday noon. I have no reason to doubt them.

In fact, Vermont is under a slight risk zone for flash flooding today and tonight. That might seem strange, given how parched it is out there. But if any particular town or area gets hit by repeated downpours over the course of a few hours, small creeks could become scary, raging torrents. There was already a flood advisory for awhile in far southern Vermont this morning when a heavy batch of rain went through there.

But still. We've been burned before. Several times this summer, the setup seemed to indicate we Green Mountain Boys and Girls would get a good soaking, and instead, we get just some crappy light showers.

It's as if we've turned into this weird humid desert. The air is so sopping wet - you'd think we'd have a downpour any minute, but then nothing happens.

No doubt it has been a hot month here in Vermont, which has exacerbated the dry condition we're experiencing. Depending upon how the last few days of the month go, we could set a record in Burlington, Vermont for the hottest month on record, which would surely be a big milestone.

Burlington, Vermont has recorded 10 days so far this month with temperatures of 90 degrees or above. We're tied with 1999 for the second most number of 90s in the month of July. The most 90s in July came in the notoriously hot summer of 1949, when there 11 such days.

Of course, we still have a few days to go in July in which the temperature could get to 90 degrees again. No such days are in the immediate future.

But......

After a break this weekend the weather pattern looks like it's going to turn once again to the one we've had this week. That means the Bermuda High will once again strengthen, pushing all the way up towards eastern New England and southeastern Canada.

Meanwhile, another dip in the jet stream will probably form to our west.

This would put us in the hot, tropical air again. I'm guessing the flood plagued Northeast (except Vermont!) would be in for more dangerous flooding, since the ground is so wet and the air will be so humid next week.

The vague bright side, of course, is despite the terrible heat and humidity we're all sick of here in Vermont, there will at least be a chance of more showers and thunderstorms next week. Even if we do get that inch of rain tonight, we'll still need more precipitation.

Flash Flooding, Other Storms Continue To Plague Nation

Good Samaritans rescue a 70 year old man from a flooded car in
Rockford, Illinois Monday.

Flash flooding is turning into a big problem in many different parts of the nation this week. Other storms have produced big hail and even a couple New Hampshire tornadoes.

I mentioned the Houghton, Michigan flood the other day. Other hard hit areas include Rockford, Illinois.

Many homes and businesses, including a hospital, were flooded there, and motorist were rescued from stranded cars. Three to five inches of rain fell in Rockford in just a few hours.

Parts of Texas, such as Port Arthur, hit so hard by Hurricane Harvey flooding last year, went under water again.

Snow plows clear heavy accumulations of hail from a highway
in Colorado this week. 

Today, the greatest risk of additional flooding includes coastal Texas and Louisiana, and an area around southeastern South Dakota and Iowa. (I hope the sump pumps are working great in my mother-in-law's house in Yankton, South Dakota!)

Meanwhile, the problem in Colorado was hail, especially in Greeley, Boulder and the Denver suburb of Aurora.

Some of the hailstones were the size of tennis balls, so you can imagine how many cars and roofs were damaged in these heavily populated areas.

Finally, we talked yesterday about those tornado warnings Monday in New Hampshire and Massachusetts.  

It turns out two tornadoes were confirmed in New Hampshire. A hiker in the White Mountains took a photo of a weak tornado skipping across the hills and forests around Lincoln, New Hampshire. Another tornado, and EFO with 75 mph winds, took a nine mile path near Bath, New Hampshire.

Here's some videos:

First,  a rescue from a flooded car in Rockford, Illinois:



Here water in Rockford gushes into a hospital:



Here's an intense hail storm in Greeley, Colorado:



In Greeley, hail washed into a low spot in one neighborhood and ended up being two to three feet deep, as this news clip shows:

Heat, Strong Storms, Local Flash Floods. It's Summer

Some thunderstorms today in Vermont could have torrenetial rains,
and might cause local flooding like this storm did last
August in Burlington

After a night that proved increasingly muggy, we've got a classic Vermont summer day coming up today. Not classic as in beautiful, like, say Friday afternoon and Saturday were.

I'm talking oppressively hot, with lots of afternoon showers and thunderstorms around. Forecasters still think some of the storms might be strong to severe, and there is a risk of one or two towns getting a flash flood today.

First, the heat. Temperatures won't be too extraordinary, but hot enough. The humidity is what's going to make today nasty. There is a heat advisory up for the Champlain Valley and southeastern Vermont. Afternoon readings before the storms will get up to near 90 degrees, but the humidity will make it fell like it's in the upper 90s.

Today is not the day you want to move that big rock pile or run a marathon. Save it for another day, bub.

There is a cold front coming in from the northwest, which means this heat and humidity is here just for today. It'll be gone tomorrow. Of course, we have to get through lots of showers and thunderstorms ahead of the cold front this afternoon and evening.

Most of us will just get garden variety storms, except many of the storms will have some torrential rain.

Early this morning, there were already some showers and storms in the Northeast Kingdom, and also just north of the Canadian border above Highgate, Vermont.

The storms will increase in coverage and intensity this afternoon. Some storms will contain microbursts, which, as I described yesterday, are intense blasts of wind and rain coming down from a collapsing thunderstorm. Microbursts cover only a small area, but the wind in these things is dangerous, and can cause a lot of damage.

We could use the rain, as it has been dry. Yet, forecasters still say one or two towns could get a flash flood out of today's weather pattern.

Most of the storms will be moving right along, so they won't sit over any particular area for a long time. That means they won't have time to dump enough rain to cause much more than some minor street flooding and a bit of erosion on your hilly driveway.

However. There's always a however. A few places might get what are known as training thunderstorms. The storms will be lined up like boxcars on a railroad track. Which means one storm after another would hit a particular place. That would be enough to cause flash flooding in the spots where the training thunderstorms hit.

The weird thing about training is one town might have some damaging flash floods while communities just a couple miles away, outside the storms, are just fine. You don't know much in advance where this will hit.

So, the best thing to do today is take it easy. Stay in the AC if you can. Listen for severe thunderstorm  and/or flash flood warnings today, and if you're area is covered by one of these alerts, get inside a nice sturdy building. Unless the nice sturdy building is in a flood prone area. Then go up to higher ground.

At least the storminess we're getting today is not nearly as bad as it was in places like Wisconsin and Michigan. There, the flash flooding was pretty extreme. As an example, here are some scenes from hilly Houghton, in the Upper Penninsula of Michigan:



Another dramatic video from Michigan:

Cape Town, South Africa Rejoices In Flash Floods; U.S., Not So Much

Reservoirs near Cape Town, South Africa are beginning to refill with
recent heavy rains, meaning a water crisis is at least temporarily averted.

For the third time this month, a major cold front smasing  into the area around Cape Town, South Africa, promising heavy rain and gusty winds.

Sounds miserable, especially after a rather wet and gloomy May, but a lot of people in and around Cape Town are delighted with the stormy weather.

CAPE TOWN RELIEF

When last we left Cape Town in this here blog thingy, the major city in South Africa was about to run out of water.

Sometime this spring, (which is autumn in the southern hemisphere, where Cape Town is) the city of about 3.7 million would run out of water due to a long, punishing drought. The plan was to haul in water from elsewhere, and give everyone a measly 25 liters per person every day at distribution sites, which is logistically very tricky. And 25 liters isn't really much water for a person's needs.

Thank goodness the rains came. Cape Town is by no means out of the woods, but reservoirs have partly refilled with the recent rains. And more precipitation is forecast this week. Again, it won't solve all the problems there, but it's a good start. Disaster has been averted for now.

Some of the storms have been heavy enough to produce some flash flooding in and are Cape Town this month. But given the apocalyptic warnings of no water this year, it seems people there are accepting the local bouts of high water on city streets.

UNITED STATES FLASH FLOODS

As usual back here in the United States, summer storms have created some pretty nasty flash floods in the past couple of days. Ground zero so far seems to be northern Minnesota, parts of Wisconsin and pieces of northwestern Michigan.

Two to 12 inches of rain fell in much of northern Wisconsin since yesterday, and flash flooding was widespread. Major highways in the region are washed out, says Minnesota Public Radio, and flash flood emergencies were in effect this morning.

Highway 23 in Minnesota was washed away by flash flooding last night. 

Thing are still ominous out there today. As of early afternoon, the flash flood region in Minnesota and Wisconsin was under a tornado watch. The storms that could cause those tornadoes will also likely unleash more heavy rain, so more flooding is still a big risk.

VERMONT STORMS?

Monday could be an interesting day in parts of Vermont with the risk of strong storms, and despite the recent very dry conditions, the slight possibility of flash floods exists around here, too.

You might have noticed this Sunday afternoon it's gotten pretty damn hot, with temperatures well into the 80s in many spots in Vermont by 1 p.m. The humidity isn't too bad -- yet.

But the humidity will dramatically increase later today and tonight, and as I mentioned yesterday, water in the atmosphere will be at near record highs across Vermont Monday.

Meanwhile, a cold front is sagging south from Canada. Before it arrives, Monday will become a miserable day, with afternoon temperatures approaching 90. That'll be combined with unbearable humidity levels.

The humidity and the approaching cold front will trigger plenty of afternoon and evening thunderstorms. A few could be severe. The biggest threat is from local microbursts. Individual microbursts rarely affect an area more than a couple miles in circumference, but they are very dangerous. 

They come when strong updrafts in a thunderstorm keep lots and lots of rain and hail suspended in the atmosphere. Then the thunderstorm loses the updraft and all that rain and hail comes crashing down to Earth in a giant gust of wind, blinding rain and hail. Microbursts can cause lots of damage, because the winds are so strong and the incredible amount of rain that can accompany them sometimes create flash floods.

The Storm Prediction Center in Norman, Oklahoma currently has all of Vermont in a slight risk zone for severe storms on Monday.

Forecasters also have us in a slight risk zone for flash flooding. As noted, it has been dry, so it would take lots of rain to cause a flash flood. There's no chance that there will be widespread flooding in Vermont with the expected downpours on Monday. There is a big however, however.

If a few torrential storms go over the same area, a couple local towns could get some dangerous flash floods along small streams, creeks, ditches and what not.

As a result, NOAA has northern New England and northern New York, including all of Vermont in a slight risk zone for flash flooding on Monday. 

We'll have updates to this on Monday morning.

Summer Thunderstorms Will Be Epic Deluges In Warmer World

Satellite view of an intense mesoscale convective complex
over Kansas in 2014. A new study says these clusters
of thunderstorms will grow more frequent and intense
as global warming ramps up. 

Another study indicates that torrential drenchings and flash floods will be more likely in the United States in a warmer world.

Several studies have linked climate change with heavier rain storms. The latest takes a look at summer thunderstorms and something called mesoscale convective systems or MCS's.

These MCS's are very common in the summer especially in the middle of the United States. They are large clusters of often torrential thunderstorms that usually erupt at night.  On average, about 60 of these things form every summer.

MCS's often bring welcome rains to the corn belt and other agricultural regions of the United States, but also sometimes cause destructive flash floods. This is especially true if a particular area is hit by several MCS's on successive nights.

In a warmer world, these MCS's would get more intense, increasing the risk of flash floods, according to the latest study, which was published Monday in Nature Climate Change.

Bob Henson, writing in Weather Underground says the study "found that increased atmospheric moisture in a warming climate will help lead to a 15 to 40 percent increase in peak MCS rainfall rates, along with a 20 to 70 percent jump in the rainfall area. Together, these lead to a 30 to 80 percent boost in the total hourly volume of rain deposited by a typical MCS."

These more vicious MCS's in the future will affect almost all of us in the United States and much of Canada and Mexico.  The study indicates the MCS's will become a bit less frequent in the central United States, (though more intense.) However, MCS's will become more frequent elsewhere, espeically in the Northeast U.S and Canada.

That increase in MCS's in the Northeast is worrisome. The Appalachian chain, including the Green Mountains here in Vermont are especially prone to flash floods as water from torrential rains tends to rush down the slopes of the mountains.

Plus, the Northeast is heavily urbanized, and storm drains aren't designed for especially heavy rains.

The bottom line: I just gave you another reason to worry about climate change.

West Coast Is Where Weather Action Is At, But Things Will Get Active Here, Eventually

Northern California fires are now largely contained, but
weather conditions could prompt new wildfires over the
next few days, especially in southern California.

Most of the weather action over the next couple of days will take place out west, especially along the West Coast, as we Vermonters bask in the very warm, sprawling high pressure system that's stuck over us and much of the rest of the East.

Here, temperatures will be way, way above normal all weekend with wall to wall sunshine, so perfect if you want to get outside to check out the lingering foliage, or just get yard work done.

But expect bad weather for that kind of thing on parts of the West Coast.

In Washington State, a very strong, wet storm is moving in this weekend. Enough rain could come with it to touch off some flash flooding. That's especially true in areas that had forest fires this summer. The trees and plants and such that held soil in place burned away, so the heavy rain get wash away dirt and fire debris and anything else. This could be dangerous.

It had been hoped that some of this rain would sneak down into the San Francisco Bay area and the Napa and Sonoma areas of California, since this is where those big, deadly wild fires were earlier this month. Some of those fires are still burning, and it would have been nice if a little of the rain from the Washington storm would move south.

Unfortunately, it's not to be. All the rain looks like it's going to stay north of this burn area. On the bright side, it did rain a little in this region Thursday, with Napa, California picking up 0.19 inches of rain. Not much, but a help. On the dark side, it looks like it's going to turn hotter and windier and drier in northern California next week.

Meanwhile, there's a strong risk of new wildfires erupting in southern California today through Tuesday. A Santa Ana event is taking shape, which would bring strong winds from the deserts, high, near record heat and very low humidity to much of southern California.

Fire warnings and excessive heat watches are in effect for much of southern California, as you's expect.

The other hotspot in the weather today is the southern and central Plains, especially around Oklahoma, where tornadoes and severe thunderstorms could erupt today.

Eventually, some of this activity out west will consolidate and set up some storminess in the eastern United States by midweek. The rain will affect Vermont, which is great since it's been so dry. We're not yet sure how much rain will come down, but we'll take anything we can get.

I had originally thought we'd get a winter preview by the end of the upcoming week. It will cool down by then, but only down to slightly warmer than normal conditions, compared to the much  warmer than average weather we're having this weekend.

Still Worried About Possible Flash Floods This Weekend

Stormy skies over St. Albans, Vermont earlier this week.
More storms, and possible flash floods, could hit
parts of the Green Mountain State over the weekend.

As of mid-morning, a band of rain was right on our doorstep moving in from the west and northwest ahead of a warm front.  

It'll be cool here in Vermont today, since the warm front won't actually move through until tomorrow, and the rain will keep the air chilled.

This afternoon and evening is really going to be a soaker, with drenching rain a sure bet.

The overall forecast hasn't changed much since I talked about this yesterday, and we're still at risk for local flash flooding over the weekend in the Green Mountain State.

There shouldn't be any substantial flooding at all today and tonight, but the rain, falling on already soggy soil, will turn the ground into wet mush and raise water levels in streams and rivers, which were already running a bit high before today's rain.

After the warm front moves through Friday morning,  we'll be in humid, warm air. Scattered thunderstorms are inevitable in such an airmass, and the moisture in the atmosphere will be increasing all day.

The Friday thunderstorms will be hit and miss, and most of them won't be big enough, or slow moving enough to cause flash floods. Still, torrential downpours falling on the soggy soil could trigger a few local bouts with high water and washouts.

A few of Friday's storms could be strong, too, with gusty winds and lots of lightning joining up with the torrential downpours. Not everybody will get at thunderstorm Friday, but those who do will sure notice it.

Saturday is the trouble day. Again, I can't guarantee any flash flooding, but thunderstorms will be very widespread, especially during the afternoon and evening. The atmosphere will be really juiced up with water, so the rainfall with these storms will be unbelievable in spots.

I'm guessing the National Weather Service in South Burlington will soon issue a flash flood watch for at parts of our area for Saturday. Stay tuned on this one.

Sunday Update On Severe Storm, Flood Threat In Northeast

Aftermath of severe flash flooding in Barre, Vermont in
May, 2011. There remains a flash flood risk in Vermont
and most of the rest of New England Monday, but let's
hope it doesn't get as bad as in this photo. 

Flash flood watches are flying for a big area of the Northeast today through Monday as a slow moving batch of severe storms with torrential rains still seem like a great bet.

The flood watch zone extends through much of New York, and from New Jersey up through all but southeastern New England.

This potential flood alert zone includes northwestern Connecticut, western Massachusetts, all of Vermont, all but eastern New Hampshire and the all of Maine except a zone within roughly 40 miles of the coast

Not every town in this zone will get a flash flood today or tomorrow, of course, but some storms will repeatedly bulleye some towns and regions, resulting in flash floods.

Yesterday, I noted there would be some adjustments to the forecast position and timing of the strongest storms and sure enough there are.

Broadly, the forecast is on track. NOAA's Storm Prediction Center has at least a slight risk of severe thunderstorms today along the entire western half of the Appalachian chain.

We're still expecting strong and severe thunderstorms to develop in New York State this afternoon, but they'll move a little faster toward the east than I thought yesterday.

This puts Vermont in play for severe thunderstorms later this afternoon and evening, especially the western half of the state. (Had the storms come through later, after daytime heating had ended, the storms would have been weaker.

The Storm Prediction Center has nudged the risk zone of severe thunderstorms into Vermont.

The upshot is across northern New York and Vermont, there could be some strong, damaging winds and torrential rains with the storms this afternoon and evening. The best shot of severe weather in Vermont is probably toward evening.

The only thing that could limit severe weather is that temperatures don't cool all that much with height. (That's called the lapse rate and would increase instability in the atmosphere.)  That could get in the way of a lot of storms forming, which means this evening wouldn't be that big a deal.

But don't count on such a reprieve.

As the National Weather Service in South Burlington, Vermont notes,  there are plenty of examples when conditions are like today's: A so-so lapse rate, but relatively strong upper level winds, hot and humid conditions and an incoming weather disturbance that have touched off a lot of severe storms. So beware.

And we ain't done after this evening.

I broader chance of severe thunderstorms exists in New England Monday.  The flash flood threat rises Monday afternoon almost regionwide, too.

If enough sun breaks through for a time Monday morning, the storms in Vermont and eastern New York could quickly become severe by afternoon. At this point I think the biggest risk of severe thunderstorms, mostly with damaging winds, would be across the eastern half of Vermont, western New Hampshire and western Massachusetts.

I actually wouldn't be totally surprised if there were a brief tornado spin up in western or central Massachusetts.

The broader threat remains localized flash floods on Monday. The air in the Northeast has far more moisture in it than normal, and the deep moisture extends high up into the atmosphere.

That means any storms that do form could contain torrential rains that come down at a rate of one to two inches per hour.

Here in Vermont, the threat of severe storms might diminish during the course of the afternoon, but there will probably still be thunderstorms around with those torrential downpours.

Since the parent cold front is moving so slowly and the air flow is parallel with this weather disturbance, we'll get into that dreaded "training" that I've referred to in past spells of flash flood threats.

As a reminder of what training is, thunderstorms often form into a line. These lines usually move generally west to east perpendicular to the orientation of the line. That means any one spot would only get a thunderstorm for an hour or less. No biggie.

When training happens, thunderstorms within the line move parallel to that line, which often stalls out. The effect of this is one thunderstorm after another moves over the same spot, like a long line of box cars on railroad tracks.

This can last for a few hours, and can result in six inches or more of rain falling in that time, leading to a local flash flood.

Some of Vermont's worst recent flash floods, including a May, 2011 disaster in and around Barre and the epic flash floods during the summer of 1998, were brought on by training thunderstorms.

There's no guarantee there will be any training box car type thunderstorms in Vermont or the rest of New England Monday, but it's something to watch.

Things start to calm down Tuesday, though the threat of heavy rain and flash flooding might linger over eastern New England.

Wisconsin, Minnesota Slammed By Floods, Storms; More Coming

Highway 11 washed out in Wisconsin after torrential
rains this week. Photo by Jeff Peters/AP

As expected, severe thunderstorms and torrential downpours have been roaming the edges of a nasty heat wave in the middle and southern parts of the country.

Some of the storms are even extending southward into the heat zone, producing some nasty storm this afternoon in Missouri and surrounding areas.

By far the worst storms so far this week have been in Minnesota and Wisconsin.

A few tornadoes touched down in Minnesota Monday. Worse, thunderstorms formed a "train" going right after another in a series over north central Minnesota and northern Wisconsin.

The storms dumped up to 11 inches of rain, so as you can imagine, there was some terrible flash flooding.

Wisconsin Gov. Scott Walker declared a disaster in eight counties. One person drowned in the flooding, and many roads have been washed away.

Some rivers in northern Wisconsin rose to record levels. Two rivers flow into Saxon Harbor at the edge of Lake Superior. The huge rush of water from the creeks flushed boats away, damaging and destroying 85 of them, says USA Today.

The flash floods in Wisconsin and Minnesota are part of a widespread pattern across the United States and much of the world of increased extreme precipitation events.

There's no way I can conclusively tie this week's Wisconsin disaster to climate change, as a lot of factors were at work to produce the storms.

But the Wisconsin and Minnesota floods fit the pattern of ever more torrential rain storms that keep cropping up.

That makes sense. A warmer atmosphere can hold more water vapor. If climate change is under way, there can be more water in the air. Under the right conditions, this added moisture is released in sometimes unprecedented downpours.

In many areas, says the EPA, a greater percentage of precipitation is coming in blockbuster one day events like the one in Wisconsin this week. This is occuring even in areas where overall precipitation is showing a decreasing trend, like in the American Southwest.

For the rest of today the target areas for severe storms are in a broad area in the Midwest and southern Great Lakes, from Wisonsin to Missouri and from Iowa to Ohio.

Some areas in this zone will be hit with strong gusty winds, maybe some hail, dangerous lightning, and of course those scary local flash floods.

Thursday, the severe risk shifts to a wide band stretching from almost all of  New England southwestward all the way to Oklahoma and Texas. (Where I am in Vermont is included in this zone of possible severe storms)

Again, the risk in most of Wednesday's alert zones are locally strong gusty winds with storms and also local flash floods.

Flash Flood Video Shows Incredible Wall of Water, Debris

Flash floods in Chile earlier this year
hit normally arid parts of that country.  

There have been a lot of flash floods around the nation this late spring and early summer. Places from Colorado to Vermont have suffered flash flood damage in just the past week.

Obviously, flash flooding can be very dangerous.

A video that emerged recently proves the point.

Heavy rain and flash flooding this past March hit what is normally an arid part of Chile.

The floods killed at least 14 people and as many as 20 people are still missing, according to published reports.

The flash flooding in the video is dramatic, and as flash floods are, very abrupt.

I don't know if I would have stood there and filmed like this guy did, but YIKES!

Here's the video:

The Flash Floods This Summer Have Been Incredible

Flooding near Islip, Long Island Wednesday.  

As I write this during my latest visit to Yankton, South Dakota, it's raining like CRAZY one state above me, up in North Dakota.    

More than five inches of rain have fallen in some areas, and it's still pouring up there. It's yet another example of a summer that has had some pretty incredible rain events.

Last week takes the cake. Especially on Long Island, where Islip had 13.57 inches of rain in one day.

Of that, 9.71 inches fell in two hours. To put that in perspective, Islip normally gets less rain than that over the course of two entire Augusts.

According to weather historian Christopher Burt, the narrow corridor of incredible rains on the East Coast is almost unprecedented. Certainly, the Islip rain was the heaviest 24 hour rainfall in New York State History.

Other areas of the East got clobbered, too. Green Haven, Maryland got 10.32 inches of rain, and Scarborough, Maine got 6.59 inches.

The rainfall rates were the big story, because in many areas, like Islip, the bulk of the rain came in two hours, three at the most. For instance, in Portland, Maine, 4.21 inches of rain fell in just two hours.

In the Northeast, rainfall in the amounts that happened in one day last week come during tropical storms or hurricanes. And it is hurricane season. However, this incredible rain had nothing to do with any tropical storm. Tropical air, yes, but not a tropical storm.

Super wet air from the tropics went up and over a weak weather front draped along the East Coast, At the points twhere the soggy, warm air had to rise over the cooler air on the other side of the weather front, the air rose, the moisture condensed, and down came the torrents.

It was also interesting to see how narrow the area of flash flooding and heavy rain was. That actually happens quite a bit in flash flood situations. One town gets blasted by the flood, and one or two towns over, there's not much to talk about.

In this case, 40 miles west of Islip, an unremarkable. 0.78 inches of rain fell during the storm. About 40 miles to the east of Islip, they only got maybe a half inch of rain. Yawn.

Damage patterns were interesting, too. On Long Island, most of the flooding was on highways and streets, and most of the damage was to cars, and some basements.

A similar torrential storm of 4.57 inches hit the Detroit area and other parts of southeastern Michigan the day before the East Coast got nailed. In the Detroit area, damage estimates are up to $1.2 billion and about 18,000 houses had flood damage, says Christopher Burt.

It all depends upon the topography, where the streams are and where the parking lots, streets and roofs prevent water from soaking into the ground.

Of course, in these extreme rain events, everybody asks if global warming has anything to do with this. Like Burt, I'm turning to Dr. Marshall Shepard, who has a great explaination about this.

Basically, he's reluctant to attribute one weather event like this to climate change, but climate change does make extreme rainfall events more likely, so we'll be seeing more of these big local flash floods.

Shepard also points out that in recent decades, a lot more urbanization with its giant parking lots, huge roofs, sprawling suburban tracts and highways mean there's too much concrete and asphalt out there to allow rain runoff to soak into the ground. Instead it pours off the parking lots and roofs and causes worse flooding.

Interestingly, social problems might have made the Detroit flooding worse, according to CBS Detroit.  The cash-strapped region had antiquated pumping stations to remove water from freeways, and thieves stealing copper pipes rom pumping stations of course made them unable to function.

So, we'll keep watching these local, devastating flash floods keep popping up worldwide. Today it's North Dakota. Who else will get washed away tomorrow.?

Summer Doldrums Contribute to Local Flash Floods

A flash flood in Jericho, Vermont in July, 2013.  

Flash flood warnings have sprouted in various sections of the country over the past few days.

We're in the peak of the season of slow moving thunderstorms. Those storms can drop major rains in a short time in local areas.

Yesterday in San Bernardino, California, flash floods and debris flows caused by slow storms caused by seasonal monsoons killed one person and stranded many others.

Flash flood warnings popped up occasionally in small areas of Pennsylvania and New York Sunday under some storms. And this morning, far northern New Hampshire and a piece of western Maine is under a flash flood warning as slow moving downpours hang out in that region.

In the height of summer, upper level winds are often slack, much lighter than they are at other times of the year. When thunderstorms form, the lame high level winds mean there's not much to push them along, so they sit over one area, dumping their rain until creeks and streams become torrents.

In the grand scheme of things, thunderstorms usually don't cover a large area. So very often in these situations, one town might have huge trouble with raging waters, while the next town three miles up the road stays totally dry.

I noticed here in Vermont that radar estimates indicate at least an inch and a half of rain fell in parts of the northeastern parts of the state, while less than a tenth of an inch had fallen in places like Burlington in western Vermont.

In the Northeast, upper level winds will pick up a little today and tomorrow ahead of a cold front.  While there will be more thunderstorms, at least they won't stay over one area too long, minimizing the flood threat.

Not so in the deserts of California, Nevada and Arizona, and on up into Utah and southern Idaho. In that region, it doesn't take a huge amount of rain to set off some flooding.

More slow moving, torrential storms are likely in that region today, meaning more flash flooding is a good bet.

On the bright side, some areas of southern California and Arizona have seen enough rain to put a teeny, tiny dent in the ongoing, severe drought out there.