根据模拟结果，未来的飓风会在美国东北部盘旋并登陆两次，可能会在新英格兰的“脆弱”地区造成严重的洪水和风暴潮。
在一项发表于年的研究中地学一个科学家小组模拟了一场假想的但在物理上看似可信的风暴“罗迪飓风”，它在新英格兰登陆后变慢，形成一个圈，两天后又返回第二次登陆。该模拟部分基于飓风酯(1961年在新英格兰附近形成了一个类似的环，但从未登陆)和其他影响该地区的风暴。
该研究由美国国土安全部资助，旨在调查新英格兰南部海岸极端飓风的潜在影响，以帮助联邦应急管理局(FEMA)和美国海岸警卫队等机构更好地为沿海社区应对未来风险做好准备。
该地区特别容易受到内陆洪水的影响，因为其河流相对较短且较浅，因此在暴雨期间更有可能产生高流量。事实上，该地区被认为是如此容易受到这些强大风暴的袭击，联邦应急管理局之前称之为“东北的致命弱点”。"
作者在研究中写道:“因此，备灾规划者必须意识到强烈飓风对该地区基础设施的潜在影响，以便制定疏散和应对计划。”。
自从欧洲移民到来后，该地区经历了几次极端飓风。然而，最近没有，这使得它对一场大风暴相对没有准备。
科学家们研究的一个问题是飓风越来越倾向于沿着北美海岸“失速”，在一个封闭的区域上空盘旋数小时——就像哈维、佛罗伦萨和最近的多里安那样。先前的研究表明自20世纪中期以来，热带气旋的平均速度已经放缓。
飓风停滞令人担忧，因为它会导致特定地区降雨量增加——导致河流泛滥——同时加剧沿海风暴潮和强风造成的破坏。
目前，还不清楚是什么导致飓风停止。气候变化是一个可能的因素。然而，这一领域的研究不如将气候变化与飓风强度和降雨量增加联系起来的证据那么确定。
在中测试的三种模拟的最坏情况下地学研究表明，罗迪以大约每小时45英里的前进速度和登陆时每小时130英里的最大风速接近新英格兰，使其成为萨菲尔-辛普森飓风等级的4级风暴。登陆后，风暴速度大大减慢，逐渐向南移动，形成一个最终会带来第二次登陆的环。模拟显示，这种情况会给该地区带来严重的洪水和风暴潮。
“因为这项研究的目的是提高当地对新英格兰南部一场大飓风袭击的潜在灾难性影响的认识，罗迪模拟的开始时间被选择为第一次登陆发生在天文涨潮的时候，”该项研究的作者之一、罗德岛大学的艾萨克·吉尼斯说新闻周刊。
“结果，纳拉甘塞特湾的最大风暴潮达到7米，[约23英尺]，导致沿海许多地区发生大面积的陆地洪水。第二次登陆期间高达20英寸的强降雨在罗德岛州引发了严重的内陆洪水，”他说。
研究人员称，这些结果对该地区的应急管理计划具有重要意义。1966年，当局建造了福克斯点飓风屏障，以保护罗德岛普罗维登斯市免受两次大规模破坏性飓风造成的大范围破坏，这两次飓风分别是1938年的新英格兰飓风和1954年的卡罗尔飓风，均在纳拉甘塞特湾以西登陆。
在最坏的情况下，罗迪的模拟表明，如果屏障保持关闭，其泵出故障——例如，由于停电或设备故障——北部将发生严重洪水。研究人员称，这凸显了纳拉甘塞特湾北部易受风暴潮和降雨引发的洪水的影响。
吉尼说:“这次模拟的重要结果是飓风屏障的关闭导致了两天后灾难性的洪水，洪水距离降雨量和河流径流高达5到6米。”。“在与罗德岛应急管理人员讨论后，在一场严重飓风中预期的大规模停电似乎将排除隔离墙的开放。”
吉尼说，伍纳斯夸塔基特河和莫沙斯克河的排放导致封闭屏障以北6米的水位升高。他说:“这些结果强调了在飓风袭击后，需要确保屏障能够打开，或者屏障的泵能够运行，以将河流流入排出屏障。”。
该团队的研究已经在现实世界中投入使用。罗德岛应急管理局和联邦应急管理局最近进行了一次为期四天的全州范围的准备演习，来自各级政府的150多名应急管理人员和其他决策者参加了演习，演习完全基于罗迪飓风模拟。据科学家称，这是第一次将计算机模拟的飓风场景用于应急训练。
吉尼说:“通常情况下，应急管理机构根据历史飓风制定飓风准备和应对计划。”。“但正如我们在最近的风暴中所看到的，比如2017年产生大量降雨的哈维飓风，飓风可能会通过公众和应急管理人员没有预料到的方式造成损害，而且可能与之前经历的风暴大相径庭。”
吉尼说，罗德岛地区早就应该迎来另一场大飓风了，因为上一场大飓风发生在1954年，尽管其影响可能与过去影响该地区的风暴不同。
“影响新英格兰的历史性飓风穿过该地区的速度相对较快，”他说。“但是飓风失速频率的增加和相关降雨量的增加很可能在未来通过与以前经历的风暴截然不同的方式产生影响。我们的研究表明，高分辨率建模可以用来模拟公众和应急管理人员没有预料到的飓风场景，并有助于更好地为未来的风暴做准备。”
研究人员没有计算出罗迪飓风发生的可能性。罗迪制作的环形飓风轨迹在大西洋非常罕见——在太平洋更常见。但基尼认为，它的主要特征，如登陆后减速和降雨量过多，预计在未来会更加频繁。
“罗迪飓风代表着罗德岛州最糟糕的情况，有多种威胁，应急机构需要用有限的资源来应对和管理，”他说。
FUTURE HURRICANE COULD LOOP AROUND AND MAKE LANDFALL TWICE IN THE U.S., CAUSING CATASTROPHIC FLOODING AND STORM SURGES
A future hurricane that loops around and makes landfall twice in the northeastern United States could cause severe flooding and storm surges in a "vulnerable" area of New England, according to modeling simulations.
In a study published in Geosciences, a team of scientists simulated a hypothetical but physically plausible storm dubbed "Hurricane Rhody" that slows down after making landfall in New England, makes a loop and returns for a second landfall two days later. The simulation was partly based on Hurricane Ester—which made a similar loop near New England in 1961, but never made landfall—and other storms that have affected the region.
The research was funded by the U.S. Department of Homeland Security and aimed to investigate the potential effects of extreme hurricanes on the coast of southern New England in order to help agencies such as the Federal Emergency Management Agency (FEMA) and the U.S. Coast Guard to better prepare coastal communities for future risks.
The area is especially vulnerable to inland flooding because its rivers are relatively short and shallow, and therefore more likely to produce high discharge during heavy rain. In fact, the region is considered so vulnerable to these powerful storms that FEMA has previously dubbed it the "Achilles' heel of the Northeast."
"Thus, it is important for preparedness planners to be aware of the potential impacts of intense hurricanes on the infrastructure of the region so that evacuation and response plans can be developed," the authors wrote in the study.
The region has experienced several extreme hurricanes since the arrival of European settlers. However, there have been none in recent times, leaving it relatively unprepared for a major storm.
One of the issues that the scientists researched is the growing tendency of hurricanes to "stall" along the North American coast, hovering above a confined region for many hours—as occurred with Harvey, Florence and, most recently, Dorian. Previous research has shown that the average speed of tropical cyclones has slowed since the mid-20th century.
Hurricane stalling is concerning because it can lead to increased rainfall over a given area—causing rivers to overflow and flood—while exacerbating coastal storm surges and the damage caused by strong winds.
At present, it is not clear what is causing hurricanes to stall. Climate change is a possible factor. However, the research in this area is not as definitive as the evidence linking climate change to an increase in hurricane intensity and quantity of rainfall produced.
In the worst case scenario of three simulations tested in the Geosciences study, Rhody approached New England with a forward speed of approximately 45 miles per hour and a maximum wind speed of 130 miles per hour at landfall, making it a Category 4 storm on the Saffir-Simpson Hurricane Wind Scale. After landfall, the storm slowed considerably, moving gradually to the south and making the loop that would eventually bring a second landfall. The simulation showed that this scenario would bring severe flooding and storm surges to the region.
"Because the aim of the study was to raise local awareness of the potentially catastrophic impacts of a major hurricane strike in southern New England, the start time of the Rhody simulation was selected such that the first landfall would occur at the time of astronomical high tide," Isaac Ginis of the University of Rhode Island, who was one of the authors of the study, told Newsweek.
"As a result, the maximum storm surge in the Narragansett Bay reached 7 meters [around 23 feet] causing extensive overland flooding in many areas along the coast. The intense rainfall—up to 20 inches—during the second landfall produced severe inland flooding throughout the state of Rhode Island," he said.
These results have significant implications for emergency management plans in the area, according to the researchers. In 1966, authorities constructed the Fox Point Hurricane Barrier to protect the city of Providence, Rhode Island, from storm surges following the extensive damage caused by two major destructive hurricanes—the Great New England Hurricane of 1938 and Hurricane Carol in 1954—which both made landfall to the west of Narragansett Bay.
In the worst-case Rhody scenario, the simulation indicated that if the barrier remains closed and its pumps fail—because of a power outage or equipment failure, for example—severe flooding would occur to the north. This highlights he vulnerability of northern Narragansett Bay to storm surges and rainfall-driven flooding, the researchers say.
"The important result of this simulation is that the closing of the hurricane barrier led to catastrophic flooding two days later of up to 5 to 6 meters from rainfall and river run-off," Ginis said. "After discussions with Rhode Island emergency managers, it appears the large-scale power outages expected in a severe hurricane will preclude the opening of the barrier."
Ginis said the discharge of the Woonasquatucket and Moshassuck rivers caused elevated waters over 6 meters north of the closed barrier. "These results emphasized the need to ensure that, after a hurricane strike, either the barrier can be opened or the barrier's pumps can be operated to discharge the river inflow across the barrier," he said.
The team's research is already being put to use in the real world. The Rhode Island Emergency Management Agency and FEMA recently conducted a four-day, statewide preparedness exercise attended by more than 150 emergency managers and other decision-makers from all levels of government, solely based on the Hurricane Rhody simulations. According to the scientists, this is the first time that a computer-simulated hurricane scenario has been used for emergency response training.
"Typically, emergency management agencies develop hurricane preparedness and response plans based on historic hurricanes," Ginis said. "But as we have seen in recent storms, such as Hurricane Harvey in 2017 that produced enormous rainfall, a hurricane may do damage through means that are not anticipated by the public and emergency managers and may be very different from previously experienced storms."
Ginis said the Rhode Island area is overdue for another big hurricane, given that the last major one took place in 1954, although the impacts will likely differ from storms that have affected the area in the past.
"The historic hurricanes that affected New England passed through the region relatively fast," he said. "But the increased frequency in hurricane stalling and the associated increase in rainfall will most likely produce in the future the impacts through means very different from previously experienced storms. Our research shows that high-resolution modeling can be used to simulate hurricane scenarios that are not anticipated by the public and emergency managers and help better prepare for future storms."
The researchers did not work out the probability of a Hurricane Rhody scenario occurring. A looping hurricane track like the one made by Rhody is quite rare in the Atlantic ocean—it's more common in the Pacific Ocean. But its main features such as slowing down after the landfall and excessive rainfall are expected to occur more often in the future, according to Ginis.
"Hurricane Rhody represents close to the worst-case scenario for Rhode Island with multiple threats that the emergency agencies need to prepare for and manage with limited resources," he said.
