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How Wind Can Change the Danger Level of a Thunderstorm

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A shelf cloud looms over the Alberta landscape during a storm in 2014. Shelf clouds are common along the leading edge of a squall line. Image credit: Jeff Wallace via Flickr // CC BY-NC 2.0

If you’re lucky, you live in a part of the world where you’ve never had to deal with damage from a nasty thunderstorm. The occasional downed tree branch or loosened piece of vinyl siding is common with even a stiff breeze, but a real bear of a storm—the kind that makes you afraid to gawk at it from your living room window—can do some serious damage in a hurry. Not all thunderstorm winds are created equal, and it’s important to know the difference between the types of winds a severe torrent can throw your way.

The two types of damaging winds you’ll experience in a thunderstorm are called straight-line winds and tornadoes. The latter doesn’t need much explanation—a tornado is a rapidly rotating column of air that stretches from the base of a thunderstorm to the ground. The United States sees about 1000 tornadoes a year, the vast majority of which touch down in the central and southern parts of the country. A decent number of those tornadoes are relatively weak, but a couple of them each year grow powerful enough to scrub even a well-built home clean from its foundation.

Odds are you’ll never see a tornado in your life, let alone find yourself in one’s path. Straight-line winds, on the other hand, are present in just about every thunderstorm, and sometimes they can cause just as much damage as a tornado.

Unlike the swirling winds of a tornado, straight-line winds all blow in the same direction. We experience these gusts every time there’s a thunderstorm; the cool burst of air you feel ahead of a storm’s arrival is the outflow produced by the storm’s downdraft, which is the rain-cooled air that sinks out of a storm and rushes out ahead of it. However, we typically reserve the term “straight-line winds” for gusts that reach severe limits, which in the United States is defined as 58 mph or stronger.

The most common types of straight-line winds you’ll encounter are downbursts, microbursts, and squall lines.

 

A microburst—the bulbous area of rain and hail beneath the base of the storm—speeding toward the ground during a thunderstorm. Image credit: NOAA via Flickr // CC BY 2.0

A downburst is a storm’s downdraft that’s strong enough to cause damage. Downbursts can be as large as a small town, covering an area a couple of miles in diameter. Microbursts are smaller, more localized downbursts that can be as small as a couple of city blocks. The strongest microbursts can reach speeds in excess of 100 mph when they slam into the ground and radiate away from the point of impact.

The abruptness of a microburst can rip roofs off of homes, mow down acres of trees in seconds, and cause arriving and departing aircraft to lose altitude and crash. Thankfully, like downbursts, we usually have the ability to detect them with enough time to warn folks to get out of harm’s way.

Squall lines occur almost every day during the warm season. If upper-level winds and instability levels are just right, single thunderstorms can congeal into a line that shares an updraft and a downdraft, moving as one entity that takes on the appearance of a semi-circle or an archery bow on weather radar (hence the squall line’s other common name, a “bow echo”).

A weather radar image shows an immense squall line stretching across Kansas on June 15, 2012. Image credit: Gibson Ridge

A squall line can be just as dangerous, if not more dangerous, than a tornado. These lines of storms can grow hundreds of miles long and stream along a path that stretches more than 1000 miles in extreme instances; these long-lived squall lines are called derechos. That’s a whole lot of real estate that’s exposed to destructive winds, with damaging gusts so intense that some people swear that they were hit by a tornado or a freak hurricane.

It’s important to know the difference between these types of damaging wind events because it reinforces how serious a severe thunderstorm is, even if there’s no threat of a tornado. Severe thunderstorms with destructive straight-line winds can cause extreme damage with a scope that goes beyond anything a tornado could ever hope to destroy.

Consider the ferocious derecho that ripped through the Great Lakes region on July 4, 1999, resulting in a massive forest blowdown; people caught in the path captured a small portion of the horrifying storm on video, showing the winds snapping tall pine trees with ease. Or the derecho in Kansas back in May 2009, which produced such strong winds that they punched a dent in the side of an 80,000-gallon barrel at an oil refinery. In addition to the rare derecho, the National Weather Service receives thousands of reports of wind damage every year from thunderstorms, ranging from downed trees and power lines to mobile homes tossed and structures shorn of their roofs.

Every severe thunderstorm is dangerous. If you ever find yourself in the path of one and hear that damaging winds are on their way, treat it as seriously as a tornado. While not as pretty or photogenic as a tornado, other winds can cause damage that is just as severe. 

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Food
Thanks to a Wet Winter, New Zealand Faces a Potential Potato Chip Shortage
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New Zealand has plenty of unique and tasty snacks, but kiwis also love potato chips. The universal comfort food is in danger Down Under, however, as an unusually wet winter has devastated the island country’s tuber crops, according to BBC News.

Twenty percent of New Zealand’s annual potato crop was wiped out from a series of major storms and floods that ravaged the nation’s North and South Islands, The Guardian reports. In some regions, up to 30 percent of potato crops were affected, with the varieties used to make chips bearing the brunt of the damage.

Potato prices spiked as farmers struggled, but the crisis—now dubbed “chipocalypse” by media outlets—didn't really make the mainstream news until supermarket chain Pak’nSave posted announcements in potato chip aisles that warned customers of a salty snack shortage until the New Year.

Pak’nSave has since rescinded this explanation, claiming instead that they made an ordering error. However, other supermarket chains say they’re working directly with potato chip suppliers to avoid any potential shortfalls, and are aware that supplies might be limited for the foreseeable future.

New Zealand’s potato farming crisis extends far beyond the snack bars at rugby matches and vending machines. Last year’s potato crops either rotted or remained un-harvested, and the ground is still too wet to plant new ones. This hurts New Zealand’s economy: The nation is the world’s ninth-largest exporter of potatoes.

Plus, potatoes “are a food staple, and this is becoming a food security issue as the effects of climate change take their toll on our potato crop,” says Chris Claridge, the chief executive of industry group Potatoes New Zealand, according to The Guardian.

In the meantime, New Zealanders are preparing to hunker down for a few long months of potential potato peril—and according to some social media users, kale chips are not a suitable alternative. “Chipocalypse” indeed.

[h/t BBC News]

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Bess Lovejoy
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Weird
The Legend (and Truth) of the Voodoo Priestess Who Haunts a Louisiana Swamp
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Bess Lovejoy

The Manchac wetlands, about a half hour northwest of New Orleans, are thick with swamp ooze. In the summer the water is pea-green, covered in tiny leaves and crawling with insects that hide in the shadows of the ancient, ghost-gray cypress trees. The boaters who enter the swamps face two main threats, aside from sunstroke and dehydration: the alligators, who mostly lurk just out of view, and the broken logs that float through the muck, remnants of the days when the swamp was home to the now-abandoned logging town of Ruddock.

But some say that anyone entering the swamp should beware a more supernatural threat—the curse of local voodoo queen Julia Brown. Brown, sometimes also called Julie White or Julia Black, is described in local legend as a voodoo priestess who lived at the edge of the swamp and worked with residents of the town of Frenier. She was known for her charms and her curses, as well as for singing eerie songs with her guitar on her porch. One of the most memorable (and disturbing) went: "One day I’m going to die and take the whole town with me."

Back when Brown was alive at the turn of the 20th century, the towns of Ruddock, Frenier, and Napton were prosperous settlements clustered on the edge of Lake Pontchartrain, sustained by logging the centuries-old cypress trees and farming cabbages in the thick black soil. The railroad was the towns' lifeline, bringing groceries from New Orleans and hauling away the logs and cabbages as far as Chicago. They had no roads, no doctors, and no electricity, but had managed to carve out cohesive and self-reliant communities.

That all changed on September 29, 1915, when a massive hurricane swept in from the Caribbean. In Frenier, where Julia lived, the storm surge rose 13 feet, and the winds howled at 125 miles an hour. Many of the townsfolk sought refuge in the railroad depot, which collapsed and killed 25 people. Altogether, close to 300 people in Louisiana died, with almost 60 in Frenier and Ruddock alone. When the storm cleared on October 1, Frenier, Ruddock, and Napton had been entirely destroyed—homes flattened, buildings demolished, and miles of railway tracks washed away. One of the few survivors later described how he’d clung to an upturned cypress tree and shut his ears against the screams of those drowning in the swamp.

The hurricane seemed to come out of nowhere. But if you listen to the guides who take tourists into the Manchac swamp, the storm was the result of the wrath of Julia Brown. Brown, they say, laid a curse on the town because she felt taken for granted—a curse that came true when the storm swept through on the day of her funeral and killed everyone around. On certain tours, the guides take people past a run-down swamp graveyard marked "1915"—it’s a prop, but a good place to tell people that Brown’s ghost still haunts the swamp, as do the souls of those who perished in the hurricane. The legend of Julia Brown has become the area's most popular ghost story, spreading to paranormal shows and even Reddit, where some claim to have seen Brown cackling at the edge of the water.

After I visited the swamp earlier this year and heard Julia Brown's story, I got curious about separating fact from fiction. It turns out Julia Brown was a real person: Census records suggest she was born Julia Bernard in Louisiana around 1845, then married a laborer named Celestin Brown in 1880. About 20 years later, the federal government gave her husband a 40-acre homestead plot to farm, property that likely passed on to Julia after her husband’s death around 1914.

Official census and property records don’t make any mention of Brown’s voodoo work, but that's not especially surprising. A modern New Orleans voodoo priestess, Bloody Mary, told Mental Floss she has found references to a voodoo priestess or queen by the name of Brown who worked in New Orleans around the 1860s before moving out to Frenier. Mary notes that because the towns had no doctors, Brown likely served as the local healer (or traiteur, a folk healer in Louisiana tradition) and midwife, using whatever knowledge and materials she could find to care for local residents.

Brown’s song is documented, too. An oral history account from long-time area resident Helen Schlosser Burg records that "Aunt Julia Brown … always sat on her front porch and played her guitar and sang songs that she would make up. The words to one of the songs she sang said that one day, she would die and everything would die with her."

There’s even one newspaper account from 1915 that describes Brown's funeral on the day of the storm. In the words of the New Orleans Times-Picayune from October 2, 1915 (warning: offensive language ahead):

Many pranks were played by wind and tide. Negroes had gathered for miles around to attend the funeral of ‘Aunt’ Julia Brown, an old negress who was well known in that section, and was a big property owner. The funeral was scheduled … and ‘Aunt’ Julia had been placed in her casket and the casket in turn had been placed in the customary wooden box and sealed. At 4 o’clock, however, the storm had become so violent that the negroes left the house in a stampede, abandoning the corpse. The corpse was found Thursday and so was the wooden box, but the casket never has been found.

Bloody Mary, however, doesn’t think Brown laid any kind of curse on the town. "Voodoo isn’t as much about curses as it is about healing," she says. The locals she has spoken to remember Julia as a beloved local healer, not a revengeful type. In fact, Mary suggests that Julia’s song may have been more warning to the townsfolk than a curse against them. Perhaps Brown even tried to perform an anti-storm ritual and was unable to stop the hurricane before it was too late. Whatever she did, Mary says, it wasn’t out of malevolence. And if she’s still in the swamp, you have less to fear from her than from the alligators.

This story originally ran in 2016.

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