Caribbean Dust, And New England The New Miami-Dade

Same two views on the island of St Barthelemy, before
the dust, top, and during the current outbreak of
Sarahan dust.  Photos by Mirco Ferro, via Twitter

We've got a this n' that post for you today, as the weather always fascinates.  Or at least gets weird pretty often.

So let's get started

SAHARA DUST

Time to head to a nice Caribbean island to enjoy the dust storms.

Wait, what?

I'm exaggerating when I'm calling the current weather in the tropical Atlantic a dust storm, but it is pretty damn dusty down there.

A huge plume of dust from the Sahara Desert in Africa has blown westward and is crossing the Atlantic Ocean.

Visibility on some islands was down to three miles or so, a sharp contrast to the deep blue skies and long views that residents and vacationers are accustomed to.

The dust will reach the U.S. Gulf Coast this week, causing hazy skies, beautiful sunrises and sunsets and maybe suppressing thunderstorms.

This cloud of dust from the Sahara desert actually isn't all that weird. These plumes of dust cross the Atlantic frequently from late spring to early fall.  This episode is just more intense than usual. Some observers are saying this plume is the thickest in five decades.

In one important respect, the dust clouds are a good thing, even if it does reduce visibility and hurt people with pre-existing respiratory problems.

The dust clouds suppress the thunderstorms needed to give birth to tropical storms and hurricanes. Such dangerous storms are much less likely when there is a plume of Sahara dust over the Atlantic.

It's early in the hurricane season now, so there probably wouldn't have been any tropical storms anyway this week, but if more dust clouds form and move out over the Atlantic, there's a chance it could reduce what is expected to be a busy hurricane season.

Don't count on that, though. Just because there's a big cloud of dust now doesn't mean it will keep happening with the same intensity all summer. and fall.  This just happens to be a random big outburst.

FLORIDA MOVES NORTH

Tropical style thunderstorm erupting Satiurday in Florida  oops
I mean Vermont. Things are a bit topsy turvy

The weather in New England has consistently been just like what you'd expect in Florida during the summer the past few days.

Heat waves hit New England almost every summer, of course. But this one has taken on the characteristics of a Florida summer.

In the Deep South, there are typically few major weather systems coming through in the summer. Cold fronts from Canada don't make it that far south, and no big storm systems come across the country to stir up the weather.  

Which means local conditions rule the roost when it comes to the weather.

In Florida's hot, humid weather sea breezes push inland, and form little weather fronts separating the marine air from the hotter conditions over land. These little weather fronts create just enough lift for daily thunderstorms in Florida during the summer.

Meanwhile, local updrafts  create more thunderstorms over interiror Florida.

Up here in New England, we're usually far enough north so that the usual roughly west to east flow of weather systems continues.  A cold front will come through with a burst of thunderstorms, followed by coolish, dry sunny weather, then a bout of hot, humid conditions, followed by another cold front, rinse and repeat.

You know the drill.

The past several days, and today, are featuring a pattern much more like Florida. There's no weather systems moving through, just a dome of hot, humid air over New England and southeastern Canada.

Which means New England is temporarily the new Miami-Dade. One of those sea breeze fronts created scattered thunderstorms a little inland from the coast in Massachusetts yesterday.

Meanwhile, local updrafts continued the daily rounds of scattered storms in interior New England. Unlike Florida, we have mountains, which are more than enough to create the initial updrafts to create those slow moving thundersetorms. They pop up, dump a big downpour on a small area, then dissipate. Then a few more form and do the same thing until the sun sets.

We'll finally revert back to typical northern weather patterns starting Tuesday.  The west to east flow of systems will resume.  A couple weak cold fronts will come through, creating a better chance of showers and storms later Tuesday and Wednesday.

The heat will then diminish, at least for awhile, starting at the end of the week.

Speaking of heat, Burlington has a shot of tying the record for the most 90 degree days in the month of June. The record is seven, set in 1949.

We've had five such days this June, and we are on track to tie the 1949 record. High temperatures in Burlington are expected to reach 90 degrees today and tomorrow.

Busy Atlantic Hurricane Season Ahead?

Satellite view of Hurricane Dorian trashing large parts of the
Bahamas last year.  Colorado State University researchers think
the 2020 Atlantic hurricane season will be busy. 

Yesterday,  I speculated about the possibility a subtropical storm forming in the Atlantic, born out of the storm that gave us Vermonters the dreary weather yesterday and today.

That's still a big question mark, but the Colorado State University Tropical Meteorology Project added fuel to the seasonal tropical expectations this year.  They're predicting a busier than normal hurricane season this summer and autumn.

They're predicting 16 named storms, compared to the normal of 12. Colorado State University says eight of those storms will be hurricanes against an average of six annually. Four of the hurricanes are predicted to be real biggies, compared to a normal of three major hurricanes.

The devil is the details, of course. Even if their forecast turns out to be spot on, Colorado State University meteorologists, or anybody else for that matter, have no idea where all these storms will form or go.

If they all somehow stay harmlessly out to sea, then it's obviously no big deal. If a lot of them start crashing onshore, especially the major hurricanes, then we have huge trouble to face.

I'm guessing you're aware there's a huge, tragic, highly disruptive pandemic going on now, and all kinds of emergency services are stretched to the breaking point. Even if the pandemic wanes over the summer - a big if - imagine trying to evacuate hundreds of thousands of people from say, Florida as a dangerous hurricane approaches.

Then deal with the aftermath - dead and injured, massive property damage, infrastructure such as roads, electricity, internet all wrecked in a big area. You can see how challenging that is in better circumstances. This is the year you really don't want to deal with this.

Last year, the United States was relatively lucky with hurricanes, even if other parts of the Atlantic Basin were clearly not so lucky.  Hurricane Dorian, which leveled parts of the Bahamas, only skirted the United States and made landfall in a weaker state in North Carolina.

Dorian did cause a lot of damage in the United States, but it could have been immensely worse. The only other highly destructive storm was Tropical Storm Imelda in Texas.  There wasn't much wind with that one, but it caused massive flooding.

We don't want years like 2017 and 2018, when destructive hurricanes hit hard in America.

One of many factors that will influence hurricanes this year is El Nino or La Ninas in the eastern Pacific. El Ninos feature warm water in parts of the eastern Pacific which help squelch Atlantic hurricanes. La Ninas, cooler water in the eastern Pacific can encourage Atlantic hurricanes.

The signals are kind of mixed this year, but feature either a situation in which there won't really be an El Nino or a La Nina. Or maybe there will be a weak La Nina.

Ocean temperatures are broadly warmer than average in the Atlantic Ocean. If that trend continues into the summer and fall, that could also encourage more and stronger tropical storms and hurricanes.

We really have to watch the Gulf of Mexico.  It's now incredibly toasty, almost at record high levels. That could change by hurricane season, but if not, that area could be a hotbed for storm development.

In the shorter term, the hot Gulf of Mexico is a potential tornado trouble maker. We're heading into peak tornado season.  A very warm Gulf would encourage warmer and more humid air than usual to make its way north into the middle of the nation.

Warmer, more humid air is one critical ingredient for severe storms.  If other conditions come together just right on occasion over the next couple of months, then tornadoes could be more destructive and frequent than usual.

Tornado season this year is already off to a bad start. So far this year there have been at least 180 tornadoes, causing 33 deaths, according to NOAA's Storm Prediction Center.

Getting back to hurricanes, the Colorado State hurricane forecast, issued Thursday, is just that, a forecast.  It's not set in stone, and like all weather predictions, especially long range forecasts, this one will surely be a little off one way or another.

Forecasters will refine tropical storm expectations as we head toward the 2020 Atlantic hurricane season.

We Actually Managed To Get Tropical Storm Arlene Out In The Atlantic

The swirls clouds in the center of this satellite photo of a
lot of clouds in the North Atlantic is Tropical Storm Arlene,
which was expected to get absorbed into the rest of the
clouds and dissipate later Friday. 

The other day, I told you about a subtropical storm trying to get going way out in the Atlantic Ocean.

It did, and did something I told you was highly unlikely: It turned into a pure tropical storm.

Yep, Tropical Storm Arlene was spinning way out in the Atlantic Ocean early Friday morning, way northwest of the Azores and way northeast of Bermuda.  It had sustained winds of 50 mph.

It joins Ana in 2003 as the only tropical storms known to have formed in the Atlantic in April.

Arlene is also the furthest north a tropical storm was found in the Atlantic this early in the season.

That doesn't mean it never happened before. Arlene was a tiny little thing embedded in a big area of storminess in the North Atlantic.

Before, say, 1970, when satellites really started taking pictures of the Earth's clouds from above, little tropical storms like this would almost surely have gone undetected.

Who knows? There might have been many April tropical storms that we never knew about.

Subtropical storms, as I mentioned the other day, are hybrids between storms with warm cores, and regular storms, that have cold upper level cores along with cold and warm fronts.

Arlene managed to transition to a warm core storm, but a lame one.

That's because it's core is indeed warmer than its surroundings, but its surroundings are cold. Water temperatures beneath Arlene are a little under 70 degrees. Usually you need water temperatures several degrees warmer than that at least to sustain a tropical storm. '

In any event, Arlene will get sucked up into the other storminess around it today and cease to exist. It poses no threat to any land areas.

Flotilla Of Icebergs Causing Problems For North Atlantic Ships

A North Atlantic iceberg a few years ago. This year, an
armada of them have disrupted shipping off the coast
 of Newfoundland, Canada

An unusually large number of icebergs have appeared off the coast of Newfoundland this month, causingn lots of problems - and dangers - for ships crossing the Atlantic Ocean.

Icebergs normally do float down from Greenland to the waters off the coast of Newfoundland in the spring and early summer.

But this year, there was a very abrupt, very big invading army of icebergs in the North Atlantic.

This is the area where the Titanic sank after hitting an iceberg in 1912.

On one day about a week ago there were about 450 icebergs in the Grand Banks waters, far more than there usually are this time of year - or any time of year for that matter, according to the Guardian. 

On average, there are about 80 icebergs lurking out there during April.

That means ships have been taking long detours to avoid the icebergs, which adds a day or more to a transatlantic crossing. And burns up more fuel, making the trip much more expensive. 

Many other cargo ships want to dock at St. John's Newfoundland, but have to slow to a crawl to avoid hitting icebergs. That also increases costs and dangers.

The number of icebergs in the North Atlantic usually peaks in May or June. The early and fast start to iceberg season raises worries the ocean off Newfoundland will really be clogged by these things in a few weeks.

Nobody knows for sure.

An "extreme ice season" is when more than 600 icebergs are spotted in a single season. It looks like this will be the fourth consecutive such season. They've kept track of these since around 1900.

The biggest recent year was 2014, when about 1,500 icebergs were spotted, the sixth highest number in a single year since 1900.

Most of the icebergs come from glaciers calving - their ends breaking off as the reach the ocean in Greenland.

This has always happened, of course, but there seems to be uptick in North Atlantic icenbergs in recent years.

Global warming could be making more icebergs calve in Greenland, sending the ice out into the North Atlantic.  There's mixed science on that: There's not a lot of good data yet on whether the icebergs from Greenland are really increasing or is this just unsual wind patterns bringing the bergs to Newfoundland? 

You need specific wind patterns to bring the icebergs into the North Atlantic. Some years, winds keep most of the icebergs away from shipping lanes.

Which means it's possible things will settle down out there in the North Atlantic.

Is Cold Spot In North Atlantic Dangerous? And Is It Climate Change?

Graphic indicates how much almost all of
the world has warmed up since 1901. But note
that spot in the North Atlantic that
has actually cooled in that time frame.  

Climate and weather watchers have been focused this winter on the patch of cold weather in the eastern United States in Canada in a world that has otherwise been really, really warm over the past few months.  

But there's another patch of chilliness that keeps appearing over the North Atlantic between Greenland and Ireland that might ultimately be more important.

It could mean that the Gulf Stream, that warm, huge current of air that flows north and northeast through the Atlantic toward Europe might be slowing down.

This has been predicted since at least the 1990s in computer models that depict the future of global warming.

It was also the plot device in the movie "The Day After Tomorrow," in which global warming shuts down the Gulf Stream, setting off a meteorological chain reaction that ultimately flooded, then sent New York City and many other parts of the world into a deep, deep fatal ice age.

Before you start panicking, we're not about to plunge into a scary ice age. The very cold and snowy winter and early spring in New England and southeastern Canada this year appears to have nothing to do with the developing cold pool in the North Atlantic.

Still, it's cause for some worry.

Eventually, if this slowing trend in the ocean currents in the North Atlantic continues, it could muck up fisheries, accelerate sea level rise along the United States and Canada east coasts, and really screw up the weather in northwestern Europe, says the online publication Vox. 

Scientists refer to the whole pattern of warm water flowing north, and colder water flowing south in the eastern Atlantic as the Atlantic overturning circulation, or if you like jumbles of letters, the AMOC.  And this circulation seems to be getting less vigorous.

Says Vox in a discussion about newly released research on the matter:

"'Nature Climate Change' argues the Atlantic overturning circulation already appears to be weakening. The researchers, led by Stefan Rahmstorf of the Potsdam Institute for Climate Research created an index of regional climate conditions going back centuries.

They find that the weakening of the AMOC appears unprecedented in the past 1,100 years, possibly due to an influx of freshwater from Greenland's melting ice caps."

As the planet warms, more and more ice melts from Greenland. That meltwater isn't salty, like the ocean. That fresh water coming into the Atlantic from Greenland reduces the density of the water in the North Atlantic, and that in turn would weaken the circulation patterns.

Like I said, climate scientist have thought this was a possibility for quite a few years now. What's surprising about the study is that the circulation pattern appears to be slowing down faster than anyboy expected.

"The slowdown we see in the data is not what you see in the climate models," Rahmstorf said.

Of course, it's always been hard to directly observe the ocean current in the Atlantic, and even harder to reconstruct how they behaved in the past.

There's always been a lot of variability to it. Sometimes it's stronger, sometimes it's weaker. The new data shows this variability, but also an overall downward trend amid the little peaks and lulls in the pace of the water's movement.

Obviously, more study is going to have to go on to figure out exactly what's happening out there.

Plus, scientists have even less of a clue about what a slowing Atlantic circulation would have on climate and the ecosystem.

There are glimmers of knowledge. Scientists do know that fisheries might collapse or change threatening the livelihood of some coastal communities in North America and Europe.

Worse, as I mentioned, slowing currents could mess with sea levels on the U.S. East Coast. Sea levels are slowly rising worldwide, but the water's going up faster in some areas than others. That has to do with ocean currents, whether the land itself is rising and sinking due to geological factors, or other issues going on.

Since the circulation as it has been working pulls warm water north, cooler water comes in to the immediate coastal areas of the East Coast to replace the warm water that flowed away. Cool water is more dense than warm.

If the circulation slows more warm water could linger near the East Coast. Since warm water is less dense, it expands a bit, which would contribute to a faster pace of sea level rise over the decades in places like New York and Boston.

Then there are uncertainties as to what effect the slowdown in circulation would have on climate. The slowdown would probably affect something called the North Atlantic Oscillation.

When the oscillation is in its positive phase, an area of low pressure that's normally near Iceland gets stronger. When that low is strong it tends to pull winds eastward, faster in eastern North America during the winter. That prevents Arctic air from plunging south very often, so you get milder winters there.

If the oscillation is negative the Iceland low is weak, there's not as much wind moving west to east, so Arctic air masses can plunge south into places like southeastern Canada and the eastern half of the United States.

The big question is, will the slowdown in the Atlantic circulations weaken or strengthen the Icelandic low in the winter? As you can see, that would have a big effect on what kind of weather we get during future winters.

Though the Atlantic Ocean circulation is expected to continue weakening, at least in general, as the climate warms, it is highly unlikely to completely shut down this century.

Which is a good thing.

The makers of that movie, "The Day After Tomorrow," got their idea from the last time the Atlantic circulation shut down, about 13,000 years ago.

The last glacial period was ending, and scientists think a big amount of freshwater melted off Greenland. Plus, something holding back a big freshwater lake that was expanding from meltwater let go, causing an immense surge of water into the North Atlantic.

All this shut down the current (remember the fresh water mucks it up), says NOAA.

That caused the northern hemisphere to plunge back into an ice age for a little while.  (In geological terms, "little while" often means thousands of years.)

The flow of freshwater abated, and then the northern hemisphere emerged from the last glacial period, and warmed up to the point we're at today.

"The Day After Tomorrow" exaggerated the speed and strength of all this, but you get the idea.

It was below zero in Vermont this morning. As I noted, this early spring cold has pretty much nothing to do with the North Atlantic and we're certainly not plummeting into another, temporary ice age.

Yet, nobody wants to inflict on distant, future generations springtimes that makes this frigid early season feel like a balmy walk along the beach in Barbados.

The North Atlantic research also demonstrates how in the long term, climate change can really screw things up in all parts of the Globe. And we don't know exactly how, or what extent this might happen, if it happens at all.

The science that climate change is certainly settled. But the eventual consequences of this change is very, very far from certain.

There will be lots and lots of work from scientists trying to sort this out in the coming years.

Hurricanes Surprise Out In The Atlantic Ocean

Hurricane Gonzalo northeast of Puerto Rico Tuesday morning.  

While we were all distracted by Pacific typhoons, Indian cyclones and tornadoes in the American South, the Atlantic Ocean has unexpectedly flared with two surprising hurricanes.

Usually, the peak of the Atlantic hurricane season is around the first half of September, but it the whole season has thankfully been rather dull this year.

We're below average in the number of hurricanes and tropical storms in the Atlantic Ocean this year.

However, we have had a late season burst. What many thought would be a mediocre tropical storm named Fay blossomed over the weekend. It blasted Bermuda with sustained winds of 61 mph with gusts to 82 mph Sunday morning.

Fay then briefly became a hurricane as it moved toward the northeast, but then died a quick death over colder ocean water and killer upper level winds that tore it apart.

Then Gonzalo formed. As of Tuesday morning, it had sustained winds of 110 mph, and was expected to strengthen to a major hurricane with 135 mph sustained winds on Wednesday.

As Gonzalo was rapidly strengthening, it caused winds of 67 mph with gusts to 88 mph on Antigua, says Dr. Jeff Masters on his Weather Underground blog.   

Luckily, it's mostly missing Puerto Rico as it curves up toward the north. It could threaten Bermuda (again!) later this week, but Gonzalo will miss the United States East Coast by a very wide margin, so we don't have to worry about that.

After Gonzalo fades away, the Atlantic Ocean will quiet down again.

Then eyes turn toward the Pacific, as Tropical Storm Ana, which might become a hurricane, could threaten Hawaii by this weekend.