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Why This Hurricane Season Has Been So Catastrophic
National Geographic ^ | 10/13/2017 | By Michael Greshko

Posted on 10/13/2017 10:01:13 AM PDT by SeekAndFind

Just as Hurricane Harvey wrapped up its devastation of Houston, Irma got into line behind it and quickly built into the strongest Atlantic hurricane in recorded history. Now, Maria leaves a broken Caribbean in its wake: Dominica's rooftops and rainforests have been ripped to shreds, and Puerto Rico may be without power for months as a result of the storm. (Learn more about how hurricanes work.)

It’s hard to avoid comparisons to the last time two such powerful storms threatened U.S. landfall in the catastrophic 2005 hurricane season, 12 years ago.

As in 2005, when Katrina and Rita devastated the Gulf Coast in rapid succession, the country is staring down the barrel of multiple hurricanes making landfall. In the face of multiple major storms, a reasonable person might wonder why this season seems worse for U.S. cities, and why the last dozen years brought fewer large hurricanes to U.S. shores.

HOW ACTIVE WAS 2017’S HURRICANE SEASON FORECAST TO BE?

Above average. The U.S. National Oceanic and Atmospheric Administration (NOAA), Colorado State University, and the Weather Channel all estimated that this year, we’d likely see more hurricanes than usual spawning in the Atlantic Ocean. NOAA’s Climate Prediction Center forecasted that we’d see between 14 to 19 named storms and five to nine hurricanes this season.

In comparison, the average hurricane season from 1981 to 2010 featured 12 named storms and six hurricanes.

WHY IS THIS SEASON SO ACTIVE?

In short: atmospheric conditions were hurricane-friendly, and surface sea temperatures were warmer than usual. The Climate Prediction Center says that multiple conditions, such as a strong west African monsoon, have aligned to make the Caribbean Sea and part of the tropical Atlantic—a storm-spawning area called the “Main Development Region”—particularly well-suited to hurricanes.

Kerry Emanuel, an atmospheric scientist at MIT who studies hurricanes, says that two factors stand out. For one, there’s currently little difference in wind speeds near the surface and those roughly 10 miles up, which ensures that miles-tall hurricanes can form and remain stable. What’s more, the tropical Atlantic is exhibiting high “thermal potential,” meaning that water can rapidly evaporate into the atmosphere.

“[Thermal potential] is a thermodynamic speed limit on hurricanes,” Emanuel says. “The greater the speed limit, the more favorable conditions are for hurricanes to form, and the more powerful they can get.”

What’s more, El Niño is stuck in neutral this year, improving Atlantic hurricanes’ prospects. When this warming of the equatorial Pacific is active, there tends to be more wind shear and less thermal potential over the Atlantic, hurting hurricanes’ chances of survival.

IT FEELS LIKE IT HAS BEEN A LONG TIME SINCE WE’VE HAD A YEAR LIKE THIS. WAS THERE REALLY A “DROUGHT” OF HURRICANES FOR MORE THAN A DECADE?

The phrase “landfall drought” refers to the fact that before Harvey, it had been nearly 12 years since a hurricane rated Category 3 or above made landfall in the U.S., going back to Hurricane Wilma in 2005.

Depending on how you define a Category 3 hurricane, this stretch had been the longest since at least 1900.

WHAT CAUSED THE DROUGHT?

Largely, it’s an artifact of how we measure hurricanes. As Hart and colleagues demonstrated in a 2016 study, if you slightly tweak the definitions of hurricane categories, the “drought” mostly vanishes.

It’s worth noting that the category system, which bins hurricanes by their maximum wind speeds, is just one way to measure hurricane intensity. By loss of life or economic toll, there’s been less of a drought to speak of.

“Tell the folks who survived [2007’s Category 2] Hurricane Ike that that wasn’t a major hurricane—it destroyed a large part of the Texas coastline,” says Emanuel. “Tell folks that Sandy wasn’t a major event… and it wasn’t even a hurricane.”

ALL THAT SAID, IS THIS SEASON UNUSUAL?

The longer it goes, the more severe it seems to get.

For starters, Irma made landfall in the Florida Keys as a Category 4 hurricane—the second Category 4 storm to make landfall on the continental U.S. this year. Such a vicious one-two punch hasn't hit the U.S. in over a century, though 1954 came close, says Florida State University meteorologist Robert Hart. That year, the Category 4 Hurricane Hazel devastated the Carolinas, and two Category 3 hurricanes just missed landfall.

But focusing on only the continental U.S. obscures the utter devastation that this hurricane season has brought to the Caribbean. Irma effectively wiped out civilization on the island of Barbuda, which had been continually inhabited for 300 years. The U.S. and British Virgin Islands have suffered horrific damage. Puerto Rico faced massive power outages in the wake of Irma—and Maria may deprive the island of power for months.

Now, in less than a day, Maria has intensified from Category 1 to Category 5, battering Dominica at full strength, with Puerto Rico still in its sights. According to meteorologist Eric Holthaus, no Category 5 hurricane has struck Dominica since at least 1851. Prior to Maria, no Category 4 storm had made landfall in Puerto Rico since 1932.

“There are no words left to describe this season,” Holthaus said on Twitter hours before Maria slammed into Dominica.

DOES A MORE ACTIVE SEASON MEAN THAT MORE HURRICANES WILL HIT LAND?

Not quite. Forecasters caution that within a single year, there’s no solid relationship between the number of storms in a hurricane season and the number of landfalls. That’s because local weather conditions govern hurricanes’ specific paths to landfall—and forecasters can estimate those only a few days in advance.

That said, Emanuel notes that on 100-year timescales, the number of hurricanes and number of landfalls correlate. However, he emphasizes the year-to-year role of chance.

“Andrew, which occurred in 1992, was at the time the most expensive hurricane ever to hit the U.S., [and] that occurred in one of the quietest years we’ve seen the Atlantic, as a whole,” he says.

SO DO SEASONAL HURRICANE FORECASTS REALLY MEAN ANYTHING?

Yes, but they’re more useful to forecasters than the public, says Emanuel. He laments that people sometimes base key decisions, such as whether to purchase insurance, on forecasts calling for “quiet” seasons—despite the fact that even seasons with few hurricanes can yield highly destructive storms, such as 1992’s Hurricane Andrew. “The seasonal forecast is so widely misinterpreted that it’s actually counterproductive,” he says.

"While the seasonal forecasts are useful across a broad range of demographics, one can’t simply and solely determine their own personal preparation based on those seasonal forecasts," adds Hart, who also points to Andrew's example.

Forecasts predicting landfall for a current hurricane, however, are another matter.

“People who are potentially in the path of a hurricane really need to pay attention and absolutely need to follow direction of emergency managers,” Emanuel says. “If you’re told to get out, get out—don’t mess around.”

HOW DOES CLIMATE CHANGE FIGURE INTO THE PICTURE?

It’s complicated, but there’s reason to think that a changing climate will have at least some impact on hurricane season activity. (Discover how climate change likely strengthened Hurricane Harvey.)

"When it comes to next year’s hurricane activity seasonal prediction, anthropogenic impacts are not a primary concern, as the change due to anthropogenic effects from this year to next year is obviously small," says Hart. "However, in the decades and century to come, it could easily become the primary concern for driving hurricane activity."

The sweeping U.S. Climate Science Special Report, prepared ahead of the U.S. government’s 2018 National Climate Assessment, says that detecting climate change’s fingerprints on hurricane behavior is challenging. Because hurricanes are rare events, there aren’t many data points for scientists to examine for a trend.

That said, in coming decades, predictions based on warming suggest that average-intensity tropical cyclones—Atlantic hurricanes included—will likely get more intense. Emanuel adds that there’s “pretty good consensus” that high-intensity (Category 3, 4, or 5) hurricanes will also become more common in coming decades.

It's unclear whether the total number of hurricanes will increase or decrease. More than 70 percent of tropical cyclones worldwide are Category 1 or 2 storms, and these weaker storms may or may not become less common in future decades.

Emanuel and the report both say that on average, individual hurricanes will drop more precipitation in the future, since warmer air can hold more water vapor. We are likely beginning to see this act out today: Every scientist contacted by National Geographic for a previous story agreed that Hurricane Harvey’s record-breaking rain was almost certainly shaped by rising temperatures from human activity.

Future storm surges may also worsen, says Emanuel—partly because the intense hurricanes that cause them will be more numerous, and partly because of sea level rise.


TOPICS: News/Current Events
KEYWORDS: climatechange; climatechangefraud; fakescience; gorebullwarming; hurricanes; natgeo
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1 posted on 10/13/2017 10:01:13 AM PDT by SeekAndFind
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To: SeekAndFind

Stop exhaling if you believe CO2 is a dangerous pollutant.


2 posted on 10/13/2017 10:03:34 AM PDT by Lurkinanloomin (Natural Born Citizen Means Born Here Of Citizen Parents - Know Islam, No Peace -No Islam, Know Peace)
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To: SeekAndFind

This season has been average.

You want a bad year for Hurricanes, try 1969, and it was more than just Camille.


3 posted on 10/13/2017 10:03:56 AM PDT by dfwgator
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To: SeekAndFind

Because Obama was no longer the President and Hillary wasn’t Elected POTUS. Duh...


4 posted on 10/13/2017 10:05:46 AM PDT by Kickass Conservative ( Democracy, two Wolves and one Sheep deciding what's for Dinner.)
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To: dfwgator

Really nasty hurricane seasons seem to cycle through every 9 to 11 years.

And that’s the way it is.


5 posted on 10/13/2017 10:06:49 AM PDT by gov_bean_ counter
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To: SeekAndFind

I’ll take ‘Climate Change’ for $100, Alex..................


6 posted on 10/13/2017 10:07:16 AM PDT by Red Badger (Road Rage lasts 5 minutes. Road Rash lasts 5 months!.....................)
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To: SeekAndFind
"...WHAT CAUSED THE DROUGHT? Largely, it’s an artifact of how we measure hurricanes. As Hart and colleagues demonstrated in a 2016 study, if you slightly tweak the definitions of hurricane categories, the “drought” mostly vanishes..."

Gee. Kind of the way employment, poverty levels, and homelessness go up and down depending on how we "define" them. When things are going good for liberal POS organizations such as National Geographic, you never hear them fiddling around with how those things are defined.

How I despise liberalism.

7 posted on 10/13/2017 10:08:16 AM PDT by rlmorel (Liberals: American Liberty is the egg that requires breaking to make their Utopian omelette.)
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To: gov_bean_ counter

And always shall be. And there ain’t a damn thing we can do about it.


8 posted on 10/13/2017 10:08:34 AM PDT by dfwgator
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The roulette wheel landed on this. Must there always be someone at fault?


9 posted on 10/13/2017 10:09:42 AM PDT by USCG SimTech
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To: dfwgator

Try 1938———one that I remember.

Terrifying.

.


10 posted on 10/13/2017 10:11:30 AM PDT by Mears
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To: SeekAndFind

Conditions aligned to contribute to good conditions for hurricane production and sustainability. Who knew this sort of thing could happen?

Talking about loads of hot air...


11 posted on 10/13/2017 10:12:38 AM PDT by DoughtyOne (John McBane is the turd in the national punch-bowl.)
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To: SeekAndFind

When you read this carefully you can conclude:

This guy has some doubts about Climate Change dogma but is too scared to speak publicly about it.

He temporizes that SOME of this COULD be climate change

Then says the future MIGHT bring more hurricane issues because of climate change.

To sum it up, it might or it might not . . . time will tell . . . I want to keep my job . . .


12 posted on 10/13/2017 10:13:04 AM PDT by LRoggy (Peter's Son's Business)
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To: SeekAndFind

Hurricanes are an ingenious part of our system.

I like cream and sugar in my coffee. It’s always better if I stir it.


13 posted on 10/13/2017 10:15:11 AM PDT by robroys woman (So you're not confused, I'm male.)
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To: Kickass Conservative
If science was behind Anthropomorphic Climate Change, you'd expect there to be a normal distribution around good effects and bad effects.

But, we only see bad effects. 100% bad effects - or more of a skewed distribution.

The only conclusion I can come up with is that it is not global climate change driven by scientists, but rather glowBull climate change driven by alarmists.

14 posted on 10/13/2017 10:15:25 AM PDT by C210N (It is easier to fool the people than convince them that they have been fooled)
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To: gov_bean_ counter

Funny how the solar flare cycles are in 11 years. I learned that from the Operating Officer at our solar observatory at the HF Receivers Site, STRATCOM Facility - Teheran 1972-1974

These were there to warn us of impending flares that obliterated out HF communication trunks to Germany, Ethiopia and Turkey.


15 posted on 10/13/2017 10:17:25 AM PDT by mazda77
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To: SeekAndFind
Article quote: "Every scientist contacted by National Geographic for a previous story agreed that Hurricane Harvey’s record-breaking rain was almost certainly shaped by rising temperatures from human activity."

It's interesting and telling that those "scientists" weren't named. I laughed at the use of the wiggle-words "almost certainly" in the quote. Remember when NG used to be scientifically credible?

16 posted on 10/13/2017 10:17:27 AM PDT by Bernard Marx
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To: SeekAndFind

Hurricane Ophelia Has Intensified As It Heads Toward Europe

17 posted on 10/13/2017 10:23:02 AM PDT by blam
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To: dfwgator

Very true.


18 posted on 10/13/2017 10:23:34 AM PDT by gov_bean_ counter
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To: blam

Wrong-way Ophelia. Isn’t that a rather unusual track?


19 posted on 10/13/2017 10:24:03 AM PDT by Pearls Before Swine (White is the new Black.)
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To: Bernard Marx
"Remember when NG used to be scientifically credible? "

Yup.

When they started the political correct BS, I cancelled.

20 posted on 10/13/2017 10:24:43 AM PDT by blam
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