Why the Weather on the Great Plains Is So Extreme

Brandi Simons/Getty Images
Brandi Simons/Getty Images

It can be tough to live on the Great Plains. The flat terrain gives way to breathtaking views of both land and sky, but the smooth, fertile land is both good fortune and a curse when it comes to the weather. Whether it's an enormous thunderstorm or a ferocious blizzard, there's rarely a dull day when it comes to weather in the middle of the country. Just what is it about the central United States that makes the weather there so extreme?

The unique geography that makes this part of the country so grand is what exposes it to some of the most extreme weather nature can produce. The Plains are bounded by the Rocky Mountains to the west, the Canadian Prairies to the north, and the Gulf of Mexico to the south. The tall, jagged mountains of the Rockies act like an atmospheric dam, forcing hot air from the south and cold air from the north to pool up over the Plains. This helps to trigger some of the most interesting weather in the world.

Most major weather events around the world are set in motion by jet streams, which are fast-moving currents of air that wrap around the planet. Straight, rigid jet streams don't result in much interesting weather, but things can get wild when the jet stream grows wavy. Sharp dips in the jet stream, called troughs, can cause low-pressure systems to develop at the surface.

When these troughs clear the Rocky Mountains in the western U.S., diverging winds in the upper atmosphere cause air to rise from the surface, leading to the development of a low-pressure system over the Plains. These lows can be the size of a single state or sprawl across the entire country from north to south. We see these storm systems most often during the winter and spring, when the jet stream is most active over the United States.

The flat land acts like an expressway, helping these fledgling low-pressure systems draw enormous amounts of tropical air from the south and, during the winter, extremely cold air from deep in the Arctic. The lack of natural obstacles allows this air to flow toward storm systems virtually unimpeded, which can lead to explosive thunderstorms during the warm months and powerful and bone-chilling blizzards during the winter.

This atmospheric expressway doesn't stop at precipitation; it's also why the central Plains can have brutal heat waves and bitter cold snaps. It's not uncommon for areas in the north-central United States to struggle to climb above 0°F for days at a time during the dead of winter, and it's similarly common for places like Oklahoma and Texas to see temperatures above 100°F for a week or longer during the summer's worst heat.

What Is a Bomb Cyclone?

Maddie Meyer/Getty Images
Maddie Meyer/Getty Images

The phrase bomb cyclone has re-entered the news this week as parts of the central U.S. face severe weather. Mountain and Midwestern states, including Colorado, Nebraska, Wyoming, and South Dakota, all fall in the path of a winter storm expected to deliver tornadoes, hail, heavy snow, flooding, and hurricane-force winds on Wednesday, March 13 into Thursday. It seems appropriate for a storm that strong to have bomb in its name, but the word actually refers to a meteorological phenomenon and not the cyclone's explosive intensity.

According to The Denver Post, the bomb in bomb cyclone stands for bombogenesis. Bombogenesis occurs when a non-tropical storm experiences at least a 24 millibar (the unit used to measure barometric pressure) drop within 24 hours. Low pressure makes for intense storms, so a bomb cyclone is a system that's built up a significant amount strength in a short length of time.

This type of storm usually depends on the ocean or another large body of water for its power. During the winter, the relatively warm air coming off the ocean and the cold air above land can collide to create a sharp drop in atmospheric pressure. Also known as a winter hurricane, this effect has produced some of the worst snowstorms to ever hit the U.S.

The fact that this latest bomb cyclone has formed nowhere near the coast makes it even more remarkable. Rather, a warm, subtropical air mass and a cold, Arctic air mass crossed paths, creating the perfect conditions for a rare bombogenesis over the Rockies and Great Plains states.

Central U.S. residents in the bomb cyclone's path have taken great precautions ahead of the storm. Over 1000 flights have been canceled for Wednesday and schools throughout Colorado have closed.

[h/t The Denver Post]

Watch a Rare ‘Ice Tsunami’ Slam Lake Erie

Clean Lakes Alliance, Flickr // CC BY 2.0
Clean Lakes Alliance, Flickr // CC BY 2.0

A combination of freezing cold temperatures and high winds is creating an unusual phenomenon along Lake Erie. As KDKA reports, ice tsunamis are toppling onto lake shores, and many locals have been asked to stay inside and even evacuate their homes.

On February 24, 2019, the National Weather Service in Buffalo, New York issued a warning about dangerous wind gusts in the Lake Erie area. The service urged citizens to seek shelter indoors and avoid traveling if possible. Winds peaked at 74 mph earlier this week, the level of a Category 1 hurricane, and tore down trees and power lines throughout the region.

People who got close to Lake Erie during the windstorm witnessed a rare event known as an ice tsunami. When wind pushed ice on the lake's surface toward the retaining wall, the sheet broke apart and dumped massive ice chunks on the shore. The video below captures the phenomenon.

In some areas, the ice piles grew so large that roadways had to be closed. Residents of Hamburg, New York's Hoover Beach area were asked to voluntarily evacuate due to the encroaching ice.

Ice tsunamis, or ice shoves, are rare, but in some cases they can be life-threatening. In 2013, waves of ice shards from a Minnesota lake destroyed people's homes.

[h/t KDKA]

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