Saturday, February 4, 2023

Scientists theorize about the “storm of the century” in the United States

Las Heavy snowfall and polar temperatures in the United States Near Christmas is caused by a weather phenomenon called a “bomb low”, caused by a depression that is rapidly intensifying, but whose historical intensity is due to cold arctic air.

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This type of storm occurs only “once in a generation”, according to the US National Weather Service in Buffalo.

Photo: AFP

We are facing a “historic cold wave”, explained Cyril Duchesne, a meteorologist for the French television channel, Chan Meteo.

With the presence of this storm, several cold records were broken: -53 °C in western Canada, -38 °C in Minnesota, but also further south, where temperatures are lower at this time of year. , -13°C in Dallas and -8°C in Houston.

The cause is a low pressure system caused by a “powerful struggle between two air masses”, one very cold from the Arctic and the other tropical from the Gulf of Mexico.

A depression is a system of low atmospheric pressure, often indicating bad weather, as it causes updrafts that lead to clouds and precipitation.

What makes the present case exceptional is that on this occasion the atmospheric pressure dropped very quickly (less than 24 hours).

This is called “explosive origin”. It occurs when the pressure in the mid-latitudes exceeds 20 hectopascals (hPa) in 24 hours.

In the case of the United States, atmospheric pressure dropped 40 hPa in 24 hours, according to Weather’n’Co meteorologist Yann Amis.

Duchesne said this led to extreme storm conditions near the center of the depression, with particularly severe conditions bringing very strong winds, blizzards and snowfall.

To him, the rarity of this storm is explained not by its cause—a “low-pressure bomb”—but by its intensity and extremely low temperature levels. “That’s what makes it extraordinary.”

What is it about? Only due to the fact that the storm causes a collapse in the polar vortex, that is, a particularly cold air mass coming from the Arctic, drawn by fluctuations of the jet stream (high altitude current), towards temperate latitudes is and is favored by anticyclonic. conditions in the Pacific.

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The result: Sometimes sharp temperature drops have been observed, such as in Denver where the thermometer dropped 33 degrees in just 7 hours on Thursday, bringing the temperature to minus 31, the coldest since 1990.

With blizzards and snowfall, the wind chill in the plains can drop as low as -55 degrees.

Cold of this magnitude can cause frostbite on exposed skin in a matter of minutes, as well as hypothermia and death if exposure is prolonged,” warned the United States National Weather Service. Makes the movement “dangerous or even at times impossible.”

By the end of this week, the depression, currently located over the Great Plains and Great Lakes levels, should move toward Quebec, which risks being “hard hit” with especially violent winds and heavy snow. and to a lesser extent towards the northeastern United States called Duchesne.

Pleca Ultima Hora


Nation World News Desk
Nation World News Desk
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