Fujiwhara effect<\/a>. This phenomenon is named for Sakuhei Fujiwhara, a scientist who studied how vortices in fluid interact. The effect occurs when tropical cyclones come within about 850 miles of each other, although the distance at which it kicks in\u2014and its end result\u2014depends on the size of each storm.<\/p>\n\u201cThey could dance around each other, and if one hurricane is a lot stronger than the other, then the smaller one will orbit around the stronger one and eventually crash into the stronger one,\u201d says Haiyan Jiang, an atmospheric scientist at Florida International University. \u201cIf the two hurricanes are closer in strength, they can just rotate around a common point.\u201d<\/p>\n
A recent example of the Fujiwhara effect occurred between Hurricanes Hilary and Irwin in the eastern Pacific in 2017; the storms eventually combined. And a rare Caribbean occurrence happened between Hurricanes Connie and Diane in 1955.<\/p>\n
Whether Humberto and the possible storm Imelda experience the Fujiwhara effect remains to be seen. First, of course, Imelda must develop into a true cyclone rather than the mess of thunderstorms that it currently is. Then it\u2019s a matter of the comparative speeds and directions of that storm and Humberto, Jiang says.<\/p>\n
Forecasting in the Face of Uncertainty<\/p>\n
Even if the storms remain too distant for the Fujiwhara effect to occur, they have already interacted, Gerard notes. On September 25 winds churned up by the developing system were caught up and blown toward Hurricane Humberto, where it became wind shear, a mess of wind that can tear apart a storm or slow its strengthening.<\/p>\n
That sort of effect from what meteorologists call outflow could be a confounding factor as the situation unfolds because existing forecast models don\u2019t re-create it realistically, Gerard says. \u201cThat certainly will be something that we\u2019ll be watching pretty closely with these two systems,\u201d he says.<\/p>\n
The two storms could also influence each others\u2019 paths, even without the Fujiwhara effect coming to pass, Gerard says. That\u2019s because, as Humberto shifts to steer northeast, its effect on the atmosphere around it may leave a trail that could attract the would-be storm Imelda, keeping the latter away from the East Coast.<\/p>\n
A key challenge of forecasting what will happen in the next couple of days is that the storm that could become Imelda does not yet have a clearly defined center around which winds rotate. Where the center develops will affect how the storm moves and reacts to the larger atmospheric environment around it. \u201cUntil we get a better handle on that, it\u2019s hard to know which of these scenarios is more likely to occur,\u201d Gerard says, noting that the system could develop a center by midday on September 27.<\/p>\n
And even beyond the storms themselves, meteorologists face additional uncertainty in drawing up a forecast. That\u2019s because of the atmospheric dynamics in the larger region, Gerard says: a pattern in the upper atmosphere over the East Coast is breaking up in an unpredictable way. How exactly this occurs will shape the way the atmosphere steers the developing storm.<\/p>\n
To a degree, meteorologists simply need time to pass in order to develop a better sense of what these storms will bring. They\u2019re also expecting data from research flights around the storm that could become Imelda, however, as well as from extra launches of weather balloons across the East Coast to understand the broader atmosphere.<\/p>\n
\u201cAll of that combined should help us get a better picture,\u201d Gerard says. \u201cHopefully, by the end of the weekend, we\u2019ll have a much better expectation of what\u2019s going to happen with all of this.\u201d<\/p>\n
In the meantime, meteorologists are already flagging that the developing storm system may push heavy rains ahead of it into the eastern Carolinas in what is formally dubbed a \u201cpredecessor rain event.\u201d Such events can leave the ground waterlogged by the time a tropical cyclone\u2019s rain arrives, making flooding more likely. The system may also approach the coastline as a Category 1 hurricane, forecasters worry.<\/p>\n
Federal Shutdown Looms<\/p>\n
Even as meteorologists wait to understand these systems better, the federal government seems to be racing toward a shutdown, which will occur on October 1 if congressional leaders cannot agree on a funding measure before then. Gerard worked for NOAA through several governmental shutdowns and worries what might happen if a shutdown and a threatening storm overlap.<\/p>\n
In terms of what might directly affect the forecast, Gerard notes that if the system that could become Imelda advances slowly, meteorologists may need data from research flights in order to understand how it will behave\u2014and it isn\u2019t clear whether such flights would take off under a shutdown.<\/p>\n
An additional concern is that reporting has suggested that President Donald Trump\u2019s administration may use a federal shutdown to initiate broadscale \u201creductions in force,\u201d as governmental layoffs are euphemistically dubbed.<\/p>\n
\u201cIt could be a much more disruptive situation\u201d than Gerard experienced during one active hurricane season he worked during a shutdown.<\/p>\n
\u201cIt\u2019s certainly not like everything just runs normally,\u201d he says of shutdown operations. \u201cThe meteorologists will still be working; the forecasts will still be going out. But there will certainly be additional complications if it\u2019s happening during a shutdown.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Editor\u2019s Note (9\/28\/25): As of 2 P.M. EDT, Potential Tropical Cyclone Nine had become Tropical Storm Imelda in…\n","protected":false},"author":2,"featured_media":52585,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[273,111,139,69,147],"class_list":{"0":"post-52584","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-environment","9":"tag-new-zealand","10":"tag-newzealand","11":"tag-nz","12":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/52584","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=52584"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/52584\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/52585"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=52584"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=52584"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=52584"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}