Article repost from https:\/\/www.vox.com\/science-and-health\/2018\/5\/31\/17406078\/hurricane-season-2018-what-to-expect<\/p>\n
This is one of the most incredible images of 2017. It\u2019s the view from a satellite from the National Oceanic and Atmospheric Administration of Hurricanes Katia and Irma and Tropical Storm Jose (from left to right) on September 8. NOAA\/NASA
\nRight now, it\u2019s the peak of hurricane season. In September, the Atlantic Ocean is the hottest it gets all year \u2014 when it\u2019s most conducive to hurricane formation.<\/p>\n
And after a slow start to the storm season this summer \u2014 there have been just six named storms, three achieving hurricane status \u2014 things are picking up in the Atlantic. Hurricane Florence is the first major hurricane, meaning with winds greater than 110 mph, of the season. Forecasters don\u2019t yet know if it will impact any land; we\u2019ll get a better picture next week. (Hurricane Lane was a major hurricane that skirted by Hawaii in August, but atmospheric scientists keep separate records for Pacific hurricanes.)<\/p>\n
At the beginning of the hurricane season in June, forecasters expected an average number of hurricanes (around seven). And it seems like the season is sticking to that mild track. The Atlantic is a bit colder than usual, and atmospheric winds have not been favorable for hurricane formation.<\/p>\n
Now is the historic peak of hurricane season. Via Colorado State
\nStill, the peak of the summer storm season is an unsettling marker because we\u2019re still reckoning with the full impact of the punishing 2017 hurricane season and the three Category 4 storms (Harvey, Irma, and Maria) that hit the US.<\/p>\n
Just recently, the government updated its official death toll from Hurricane Maria in Puerto Rico: 2,975 people died as a result of the hurricane and the subsequent humanitarian crisis. Other reports estimate the death toll could be even higher. In June, the New England Journal of Medicine published a report finding that the death toll from Hurricane Maria could be more than 4,600.<\/p>\n
It\u2019s easy to feel helpless in the face of these storms. But thankfully, atmospheric scientists have made huge strides in forecasting the path of storms and how these storms might grow in a climate-changing world. That helps us prepare for the worst.<\/p>\n
Here\u2019s what we\u2019ve learned in the months since last year\u2019s Atlantic storms and what we can expect in the months ahead.<\/p>\n
The 2018 hurricane outlook looks normal. But there\u2019s much uncertainty.
\nEvery year from June through November, there\u2019s a risk of powerful storms in the Atlantic.<\/p>\n
In late May, forecasters at the National Oceanic and Atmospheric Administration predicted that the season will be average or slightly above the norm. Specifically, the forecast has a 70 percent chance of seeing between five and nine hurricanes, with a total of 10 to 16 named storms. (Some of those named storms would not be strong enough to attain hurricane status.)<\/p>\n
In a more recent analysis, conducted in early August, atmospheric scientists at Colorado State University forecast a below-average season with nine named storms, three becoming hurricanes. \u201cThe tropical Atlantic remains anomalously cool, and vertical wind shear across the Caribbean has been quite strong over the past month,\u201d the report stated. These are conditions not conducive to strong storm formation.<\/p>\n
Indeed, there\u2019s a lot of uncertainty built into seasonal hurricane forecasting. Last May, NOAA predicted an above-normal year for hurricanes. But no one saw the back-to-back-to-back pattern of the storms coming \u2014 a grand total of 17 named storms, 10 of which were hurricanes. No one knew it would be one of the 10 most intense hurricane seasons on record.<\/p>\n
It\u2019s hard to predict the number of hurricanes because they\u2019re formed by a complicated interplay of climate and weather variables. Yes, warm waters are a key ingredient to fuel storms. But hurricanes are also influenced and steered by massive global trends in weather that are hard to predict: The warming or cooling of waters in the Pacific (El Ni\u00f1o and La Ni\u00f1a), patterns like the Madden-Julian oscillation (an eastward-moving weather system that circles the globe every month or so and makes thunderstorms more likely), and temperature differences between the surface and the higher reaches of the atmosphere all play a role.<\/p>\n
Also, NOAA just makes predictions about storm formations, not landfalls. \u201cHurricane landfalls are largely determined by the weather patterns in place as the hurricane approaches,\u201d NOAA noted in its early season forecast. We could have an extremely active hurricane season that never harms a single person on land.<\/p>\n
What we\u2019ve learned: hurricanes are growing wetter and slower
\nLast August, Hurricane Harvey dumped a record-shattering 60 inches of rain over some parts of Texas. Over the course of the storm, it\u2019s estimated 24 trillion to 34 trillion gallons of water fell in the area. And the weight of that water was so heavy, it actually depressed the earth more than half an inch in some spots, according to the Scripps Institution of Oceanography.<\/p>\n
Climate scientists have now determined via two separate research efforts that Hurricane Harvey\u2019s record-blasting rains (best measured in feet for much of Houston) were likely amplified by climate change.<\/p>\n
\u201cHuman-induced climate change likely increased Harvey\u2019s total rainfall around Houston by at least 19 percent, with a best estimate of 37 percent,\u201d Michael Wehner, a co-author on an attribution study recently published in Geophysical Research Letters, said at the American Geophysical Union conference in December. And the corresponding study in Environmental Research Letters concluded that climate change increased flooding by around 15 percent.<\/p>\n
The rainfall increased, in part, because of how abnormally hot the Gulf of Mexico was last summer. Last August, the Gulf reached its highest temperatures on record, a report published by the American Geophysical Union found.<\/p>\n
Even with climate change, Harvey\u2019s rain was an extremely rare event, expected not to return for thousands of years, Karin van der Wiel, another author of the Environmental Research Letters study, said. Still, the odds of seeing such an extreme event have changed, she says. \u201cIt\u2019s between 1.5 and 5 times more likely now than in preindustrial times.\u201d<\/p>\n
And research suggests wetter storms are in our future. More recently, the National Center for Atmospheric Research published a study in the Journal of Climate simulating a what-if scenario on 22 recent hurricanes. The question: What if these storms formed at the end of the 21st century, in a warmer world?<\/p>\n
The hurricanes didn\u2019t grow that much more intense in the simulated model. But they almost all became wetter, spewing more rain. On average, the model found a 25 percent increase in rainfall across the storms \u2014 enough to make the difference between a bad flood and a catastrophe.<\/p>\n
Climate change science also predicts that storms might grow bigger and more frequent in a warming world, but it\u2019s not quite yet clear if that trend has begun in earnest.<\/p>\n
And not only are hurricanes getting wetter, there\u2019s some new evidence that the rate they travel across the globe is slowing down. A new study in Nature finds that hurricanes, on average, moved 1.2 mph slower in 2016 than they did in 1949.<\/p>\n
This isn\u2019t about wind speed; rather, it means hurricanes could spend more time lingering over a particular area. And the more time a hurricane spends over an area, the more wind, rain, and damage can be expected. The researchers aren\u2019t entirely sure what\u2019s causing the slowdown, but climate change is a prime suspect. There\u2019s some evidence that climate change is contributing to a weakening of atmospheric circulation in tropical regions. And that could be a reason hurricanes are in less of a hurry.<\/p>\n
Good news: hurricane tracking and forecasts keep getting better
\nHere\u2019s some good news: In 2017, the NHC\u2019s predictions 72 hours in advance of a storm were more accurate than its predictions 24 hours in advance of a storm in 1990. Last year, we saw an incredibly active hurricane season. But we also saw the most accurate storm-path predictions on record, according to a recent NOAA report. That helps communities prepare and potentially saves lives.<\/p>\n
Consider what happened with Hurricane Irma last year. That storm skirted through the Caribbean and then took a nearly 90-degree turn northward toward Florida. The NHC predicted this northward turn would happen four days out. There was some uncertainty if the storm was going to impact the Gulf Coast or the Atlantic Coast. \u201cBut the fact it was known a few days in advance that the storm was likely to do that was an incredible feat of tech and science,\u201d Rebecca Morss, a scientist at the National Center for Atmospheric Research, said in an interview last year.<\/p>\n
Improvements in computer models, computer processors, and data collection (obtained via actually flying planes through hurricanes) all contribute to this great increase in predictive power.<\/p>\n
But challenges in forecasting still remain. The chart above shows advances in predicting the path a hurricane will take. Predicting intensity \u2014 how strong its winds will be \u2014 is a much harder thing to do, and 2017\u2019s intensity forecasts didn\u2019t show much improvement compared to the past several years.<\/p>\n
It\u2019s harder because there are so many factors that go into a hurricane\u2019s intensity: ocean temperatures, wind shear higher up in the atmosphere, interactions with land. Atmospheric scientists don\u2019t yet have the density of data or the computer models to make huge improvements in this area.<\/p>\n
Recently, forecasters were caught off guard by the sudden intensification of Hurricane Florence, a case in point of how tricky forecasting hurricane intensity can be.<\/p>\n
View image on TwitterView image on TwitterView image on Twitter<\/p>\n
Michael Lowry
\n\u2714
\n@MichaelRLowry
\n#Florence is now a borderline Category 4 #hurricane. None of our forecast models saw this sort of strengthening in the face of 20-25 kt shear. We’ve made great strides in forecasting, but still a lot left to learn. (satellite via @UWSSEC, plots via @HurricaneModels)<\/p>\n
12:26 PM – Sep 5, 2018
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\nBut overall, the trend of increasingly accurate forecasts is likely to continue. NOAA has launched two new satellites monitoring into our atmosphere this year. And it continues to update its computer models to make forecasts.<\/p>\n
There may be destructive storms, but we\u2019ll see them coming.<\/p>","protected":false},"excerpt":{"rendered":"
Article repost from https:\/\/www.vox.com\/science-and-health\/2018\/5\/31\/17406078\/hurricane-season-2018-what-to-expect This is one of the most incredible images of 2017. It\u2019s the view from a satellite from the National Oceanic and Atmospheric Administration of Hurricanes Katia and Irma and Tropical Storm Jose (from left to right) on September 8. NOAA\/NASA Right now, it\u2019s the peak of hurricane season. In September, the […]<\/p>\n","protected":false},"author":2,"featured_media":17103,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_angie_page":false,"page_builder":"","footnotes":""},"categories":[78],"tags":[179,61],"class_list":["post-14989","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-caribbean","tag-news"],"yoast_head":"\n