Why Irma is so strong and other questions about hurricanes
Why Irma is so strong and other questions about hurricanes Winds brought by Hurricane Irma blow palm trees lining the seawall in Caibarien, Cuba, Friday, Sept. 8, 2017. (AP Photo/Desmond Boylan/Ian Brown)
Why Irma is so strong and other questions about hurricanes
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A powerful Hurricane Irma is threatening millions of people in the Caribbean and Florida, so here are answers to questions about Irma and hurricanes.


Irma is a classic Cape Verde storm, which begin near the islands off the west coast of Africa. Some of the worst hurricanes start as puffs of unstable air and storminess there and chug west, gaining strength over the warm open Atlantic. Another storm, Jose, has followed in Irma's footsteps. Some of those storms fizzle from wind shear or other weather conditions, while still others curve harmlessly north into the mid-North Atlantic and are called "fish storms." Storms also start in the Gulf of Mexico, like Katia which formed off Mexico and was declared a hurricane on Wednesday.


Hurricane season starts June 1 and ends Nov. 30, usually when the water is warm enough and other weather conditions are conducive to storm formation. Hurricanes need water that's at least 79 degrees (26 degrees Celsius). Peak hurricane season is from mid-August to mid-October with the peak of the peak being Sept. 10 or 11.


An average season produces 12 named storms, according to the National Weather Service. Wednesday's Katia is the 11th this season. Storms get names when winds reach 39 mph. The average season produces six hurricanes and three of those become major at 111 mph winds or higher. So far this year, there have been six hurricanes: two major ones, Harvey and Irma; two new ones Wednesday, Katia and Jose; and Franklin and Gert.


Yes. In May, the weather service predicted a 70 percent likelihood of 11 to 17 named storms with 5 to 9 becoming hurricanes, predicting 2 to 4 major hurricanes. In early August, it was changed to a 60 percent chance of 14 to 19 named storms, 5 to 9 hurricanes and 2 to 5 major hurricanes.


Major storms can and do form back-to-back and did so last year with Matthew and Nicole, but having more than one hit the U.S. in a season is strange. If Irma hits Florida as a category 4 or 5 storm, it will be the first time in historical record that the U.S. was hit by two category 4 or 5 storms in one year, said Colorado State University meteorology professor Phil Klotzbach.


Hurricanes use warm water as fuel. Irma has been over water that is 1.2 to 1.8 degrees (0.7 to 1 degree Celsius) warmer than normal and that warm water goes deeper than usual. High altitude winds, which can fight or even decapitate storms, are not strong, also helping Irma. While over the open Atlantic Ocean on Tuesday, Irma's 185 mph winds set a record for that region. In the entire Atlantic, Caribbean, and Gulf of Mexico, only Hurricane Allen in 1980 was stronger with 190 mph winds; others with 185 mph winds: a 1935 Florida storm, 1988's Gilbert, and 2005's Wilma.


This is only the second time since satellite-tracking began about 40 years ago that one maintained 185 mph winds for more than 24 hours, said Klotzbach, and the other was the massive killer typhoon Haiyan that killed more than 6,000 people in the Philippines in 2013.


Scientists take weeks or months to conduct intricate studies, using computer simulations, to see if a storm was worsened by man-made climate change. There have been a limited number of hurricanes since record-keeping began in 1851, which makes it difficult to do robust statistical analyses. However, scientists have long said future global warming would make some of the worst storms stronger and wetter and recently have linked climate change to future rapid intensification of storms -  this has led to scientific debate over whether global warming means more storms, but the stronger and wetter is generally accepted by scientists.


In the U.S., yes, until Harvey last month, no major hurricane had hit the United States since Wilma - that 2005 storm also was the last major hurricane to hit Florida. Scientists say the 12-year landfall drought was likely chance, but there were still the same number of hurricanes brewing, they just missed the United States or were not major hurricanes. During that span, Superstorm Sandy was a minor hurricane in terms of wind speed but catastrophic in damage when it hit in 2012.


Forecasters at the National Hurricane Center rely on dozens of computer simulations and their own expert experience, using real-time readings of wind, temperature, air pressure, humidity and more, but those real-time readings are sparse and spread out and figuring out a storm's path and strength is tricky and usually forecasts do not go out further than five days.

Source URL: https://www.tweentribune.com/article/teen/why-irma-so-strong-and-other-questions-about-hurricanes/

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Why have predictions become more accurate?
Write your answers in the comments section below

  • madysonw-cel
    9/13/2017 - 12:03 p.m.

    The National Hurricane Society relies on many different computer simulations and their own experience with hurricanes. To predict how strong the storm is and the path of the storm is difficult.They use real-time readings of wind, temperature, air pressure, and humidity to make predictions, but the predictions usually change and forecasts do not go out further than five days.

  • ionicaj-cel
    9/13/2017 - 12:22 p.m.

    This hurricane had everyone in my town shook and we don't even live in Florida. Every store was out of cases of water, flashlights, candles, and basically every type of "survival" supply. I don't know how it went from a category 5 to a category 1 in the matter of days but I'm glad it did. It just rained a little bit. This hurricane was over exaggerated in my area.

  • victoriai-hol
    9/15/2017 - 10:03 a.m.

    Predictions have become more accurate buy using computer simulations, expert experience, and live-time readings of wind, temperature, air pressure, and humidity, when all of those combined and you can tell whats going to happen and when.

  • CJ@Arnn-dav
    9/21/2017 - 01:12 a.m.

    I think that part of the reason why the the predictions have become more accurate are because they are studying deeper into Hurricanes and I think that when they study the Hurricanes more they will be able to guess better about what's going to happen according other hurricanes in the past.That is why I think predictions are becoming more accurate.

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