STORM SCOURGE 

UPDATE: More than 130 tornadoes were reported across the U.S. Southeast Wednesday, including several linked to large numbers of deaths in Mississippi, Alabama, Georgia, Tennessee and Virginia. See NOAA's Storm Prediction Center and stay tuned to MNN's severe weather updates for more details. 

Another "explosive" storm system is plowing through the eastern third of the U.S. today, bringing with it heavy rain, howling winds, violent tornadoes and baseball-sized hail, the National Weather Service warns. These thunderstorms are the remnants of a system that killed at least one person in Arkansas Tuesday night, raising that state's two-day death toll to 11, and also wreaked havoc in Missouri, Tennessee and East Texas. It's all part of a broader weather pattern that's plagued the central U.S. for weeks, fueled by moisture from the Gulf of Mexico and a low-slung jet stream. "The storms are just amazingly explosive and they're covering a very large area," NWS meteorologist Greg Carbin tells CNN. "We may finish out April with more than 300 tornadoes. It looks like it will be a record-breaker as far as sheer numbers go."

[skipwords]In addition to all the tornadoes, the storms have dumped huge amounts of rain across the region, pushing several rivers well beyond their banks. Missouri's Black River broke through earthen levees in multiple places Tuesday, while the Ohio River in Kentucky swelled "like an ocean," a local farmer tells the Wall Street Journal. In Natchez, Miss., the NWS predicts the Mississippi River will crest at 60 feet next month, surpassing its record high of 56.6 feet set in 1927 — a devastating flood that swamped 26,000 square miles and killed more than 200 people. The Mississippi is so out of control, in fact, the U.S. Army Corps of Engineers is mulling a controversial plan to blow up a levee at Birds Point, Mo., in hopes of preventing more severe flooding downstream, where the Ohio and Mississippi rivers intersect. The plan would send floodwaters gushing across 130,000 acres of Missouri farmland before they rejoin the Mississippi 35 miles to the south, near New Madrid, Mo. That strategy was approved back in the 1920s, the WSJ notes, but has been used only once since then. Missouri officials are trying to block the move in federal court, arguing it will ruin too much prime farmland. 

Meanwhile, the destruction from Monday's and Tuesday's tornadoes has left much of Arkansas and East Texas in shambles, and foreshadows a similar fate for much of the Tennessee Valley today, AccuWeather reports. The storms have already reached parts of northern Mississippi, Alabama, west Tennessee and southern Kentucky, and are forecast to continue radiating across the Eastern Seaboard through tonight. The danger of severe weather extends from the Mississippi River to Appalachia, with powerful tornadoes expected around many populated areas, including Greenwood, Miss.; Tupelo, Miss.; Birmingham, Ala.; Huntsville, Ala.; Nashville, Tenn.; Chattanooga, Tenn.; and Rome, Ga. "If strong tornadoes like this hit any populated area, they could result in complete destruction," AccuWeather meteorologist Heather Buchman warns.[/skipwords]

(Sources: National Weather Service, CNN, AccuWeather, Wall Street Journal, Associated Press, Reuters)

SCORCHED EARTH 

While this week's thunderstorms have brought badly needed rain to parts of East Texas, much of the state is still mired in a crippling drought, ClimateWire reports, and remains engulfed in some of the worst wildfires in its modern history. Roughly 1.5 million acres have already burned so far this year, the Texas Forest Service estimates, and even the thunderstorms present a double-edged sword, since lightning strikes can ignite new fires. With strong winds expected to gust into Texas at 50 mph in the coming days, the forest service warns of "sleepers," or smoldering embers first lit by lightning and later swept into full-fledged wildfires by wind.

Temperatures are also soaring into the 90s and even 100s in South Texas, where AccuWeather forecasts an "extreme" fire danger today before the area gets a brief break Thursday. There are 11 large, uncontained fires still burning in western, northern and eastern Texas, as well as many smaller fires scattered throughout the state, and the region's long-running drought isn't expected to let up anytime soon. Most of the state is gripped by droughts ranking either "severe," "extreme" or "exceptional," and drier-than-normal conditions are forecast to continue through the summer. Firefighters from 43 states are battling the blazes in Texas, and almost all of the U.S. air tankers available to fight wildfires nationwide are now being used in the state, ClimateWire reports. With warm, dry conditions also likely to persist for months in Florida, southern Georgia, southeastern South Carolina, Oklahoma, New Mexico, Arizona and southern Colorado, that could stretch the country's firefighting resources.

While neither the recent string of severe thunderstorms or severe wildfires can be traced directly to broader climate trends, scientists widely expect global warming to make such extreme weather more common. And as Texas state climatologist John Nielson-Gammon tells ClimateWire, climate change likely did help create the conditions behind Texas' current infernos. "Global warming probably produced a slight enhancement of the rainfall, leading to a little extra plant growth," he says. "Also, the warm temperatures during the past couple of months are probably a degree or two warmer than they would have been without the rise in global temperatures, thereby increasing the dryness."

(Sources: ClimateWire, AccuWeather, U.S. Drought Monitor)

BIRD BRAINS 

[skipwords]Lots of animals have proved themselves capable of adapting to city life, from squirrels and pigeons to coyotes and cockroaches. But according to a new study in the journal Biology Letters, some urban birds actually have bigger brains relative to their body size than their country cousins, suggesting they're more adaptable to the chaotic conditions of city living. The discovery may also shed light on how human civilization influences natural selection among city-dwelling animals, the researchers say.

The study focused on 12 cities in France and Switzerland, with the researchers hoping to better understand why certain bird species are more successful in urban environments than others. "We were interested whether behavioral flexibility can increase the chance of a given species to successfully colonize cities," evolutionary biologist Alexei Maklakov tells the BBC. "After all, a center of a modern city is a novel and rather harsh environment for most species, and the ability to sustain a varied diet or develop novel foraging techniques, and perhaps utilize non-standard nesting places, can be beneficial." By examining family trees of several bird species — including crows, nuthatches, tits and wrens — the researchers found one key similarity among all the "urban adapters": larger brains. 

Previous studies have linked brain size to behavioral innovations in birds and mammals, and the authors of the new study say their findings show how bigger brains and increased creativity can help species survive in cities. They might also prove helpful for efforts to conserve less urban-adapted species, the researchers add. "[The study] suggests that some species and even whole families of birds are less likely to adapt to novel conditions," Maklakov says, "and if we want to see them in the cities we will have to create patches of their original habitat."[/skipwords]

(Source: BBC News)

CLEARING THE AIR 

The air is getting cleaner in most of the dirtiest U.S. cities, according to a new report from the American Lung Association, but about half of all Americans still live in places where breathing is often a health hazard. As USA Today points out, the ALA's 12th annual "State of the Air" report comes at a pivotal time for U.S. air quality, as Congress strips millions of dollars from the EPA's budget and continues efforts to prevent the agency from regulating air pollutants, including greenhouse gases, under the Clean Air Act. 

"We're very pleased to report great progress," ALA President Charles Connor said in a statement accompanying the report, which is based on the most recently released EPA data. Still, he adds, "Air pollution remains a very real health threat." The EPA data reflect pollution levels from 2009, and show a 6.1 percent drop in greenhouse gas emissions from 2008, the largest decline in at least five years, USA Today reports. The agency cites the recent recession as well as a gradual switch to less polluting fuels as likely causes for the decline, while the ALA's Janice Nolan adds that improvements under the Clean Air Act had already begun to bear fruit even before the economic downturn. 

The report shows that all 25 cities with the most ground-level ozone saw their air quality improve between '08 and '09, while all but two with the worst year-round particle pollution also saw improvements (but only 12 of the 28 cities with the worst short-term levels of particulate matter enjoyed similar trends). The Los Angeles metro area is still the country's smoggiest, although it has reduced smog levels significantly in recent years, and Bakersfield, Calif., remains No. 1 for particulates. Meanwhile, more than 154 million Americans live in counties with dangerous levels of either ozone or particle pollution, the ALA notes.

(Sources: USA Today, American Lung Association)

THIS DAY IN HISTORY

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Photo (thunderstorm over Dallas on April 23): David Berkowitz/Flickr

Photo (wildfire near Swenson, Texas, on April 8): Texas Governor's Office

Photo (pigeon overlooking New York City): Ava Lowery/Flickr

Photo (smog over Los Angeles): Steven Buss/Flickr

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