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Look for a near-normal Atlantic hurricane season this year. That's the outlook from several groups who produce seasonalforecasts for the Atlantic hurricane season, which began Friday. Here's a sampler: The National Oceanic and Atmospheric Administrationanticipates a 70 percent chance that from nine to 15 storms willreach tropical-storm status and earn names. Between four and eightwill become hurricanes. Of those, from one to three are expected tobecome major hurricanes, where maximum sustained winds top 111miles an hour. At Colorado State University, where atmospheric scientistWilliam Gray pioneered seasonal tropical cyclone forecasts, he andcolleague Philip Klotzbach anticipate 13 named storms, fivehurricanes, and two major hurricanes. Researchers at Florida State University give the season a 70percent chance of producing 10 to 16 named storms, and from five tonine hurricanes. Tropical Storm Risk.com, a consortium of scientists andinsurance-industry specialists based in Britain, is anticipating(in round numbers) 13 tropical storms, six hurricanes, and threemajor hurricanes. The average between 1981 and 2010, the base period federalforecasters now use for determining above- or below-normalconditions, is 12 named storms a year, of which half reachhurricane status. Several factors are contributing to the near-normal outlook. Amongthem, sea-surface temperatures in regions where the Atlantic'stropical cyclones form, and conditions in the tropical Pacific thathave an extended influence over weather patterns elsewhere. Tropical cyclones form over and feed off of warm surface waters.And while still warm by snow-bird standards, waters across thetropical Atlantic from Africa to Central America have posted theirthird-coolest May readings since 1995, when the current, relativelyintense long-term period of tropical-cyclone activity began, notesJeff Masters, a meteorologist and co-founder of the website WeatherUnderground. Sea surface temperatures are running only about a halfa degree Fahrenheit above normal, suggesting that it may takelonger for waters to warm enough to fuel tropical cyclones. But he also points to a broad patch of unusually warm water runningup the East Coast from Virginia through southern New England.There, average surface temperatures are running up to 7 degrees ormore Fahrenheit above normal perhaps setting the stage forsustaining or intensifying the strength of any hurricane thattravels up the eastern seaboard. Another key factor is the state of the tropical Pacific's ElNi o-La Ni a cycle. Over the past two hurricane seasons, La Ni a has held sway characterized by cooler than normal sea-surface temperatures in theeastern tropical Pacific and warmer than normal temperatures in thewestern tropical Pacific. These conditions flip-flop under ElNi o. Each phase of this cycle alters wind patterns in ways thatinhibit tropical-cyclone formation in the Atlantic during an ElNi o and favor cyclone formation during a La Ni a. La Ni a fizzled in April, leaving current conditions in aneutral phase some forecasters whimsically refer to as La Nada.Some models are forecasting the development of a weak El Ni obetween July and August, but for now it's unclear whether it wouldlast much beyond that. Indeed, the season's two early storms in May, Alberto and Beryl,highlight the influence wind conditions have. Both strengthened totropical-storm levels over warm Gulf Stream waters off the coastsof Florida and the Carolinas. But they did so because the system ofcloudiness they grew from traveled into a gap between twohigh-altitude rivers of air flowing west to east the polar andsubtropical jet streams, Dr. Masters explains on his WeatherUnderground blog. Both can meander over the area where the two storms intensified. Ifthe storms had encountered either, the high winds would havesheared off cloud-tops and prevented intensification. I am an expert from roll-formingmachinery.com, while we provides the quality product, such as Wind Tower Production Line , China Tank Welding Machine, H Beam Welding,and more.
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