An atmospheric Category 5 river – extending 2,700 miles across the Pacific – is flooding the northwestern United States.

An atmospheric Category 5 river – extending 2,700 miles across the Pacific – is flooding the northwestern United States.

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This year, Seattle had almost 6.5 “of rain. With an additional forecast of 5 to 10 cm, the city can receive about 25% of its annual precipitation until January 15, coming from the atmospheric river that is flooding the region.

“This soggy start could propel Seattle to its wetest start of any year on record. The previous wetest period from January 1 to 15 occurred in January 1956, when nearly 18 centimeters fell in the first half of the month,” said the CNN meteorologist Pedram Javaheri.

Atmospheric rivers are long, narrow regions in the atmosphere – like rivers in the sky – that carry water vapor, according to the National Oceanic and Atmospheric Administration.

This atmospheric river event is being classified as Category 5 – the highest level – of the Western Water and Climate Center. The potential for flooding is enormous, with about 15 million people under some form of surveillance or counseling. Western parts of Washington can see 300% of normal rainfall, according to the Weather Forecast Center.
“Soil saturation levels are ranging from 75-95% over the western third of the region now. It won’t take much rain to lead to surface flooding, ”says Javaheri.
Check the forecast across the countryy

There is also a lot of heat in the medium levels of the atmosphere during this specific atmospheric fluvial event. This will increase snow levels at altitudes above 6,000 feet across much of the Cascades, with rain falling below that level.

“This will further exacerbate concerns about flooding, as heavy rains fall on heavy snow. The threat of rapid thaw, increased runoff and flooding downstream is something that everyone in western Oregon and Washington should do. be alert, “said Javaheri.

Higher elevations in Washington can cause 5 to 10 cm of rain during the next 24 hours, increasing the risk of floods and landslides.

The forecast models show the humidity - shown in blue - extending for thousands of kilometers.

Precipitation at lower altitudes should be between 1 and 2 inches during that time.

In Portland, Oregon, the National Weather Service Office predicted up to 7 inches of rain on higher ground and up to 2 inches for the lowlands by Wednesday morning. Along with that, there is a strong wind alert in place.

Five to ten centimeters of additional rain is possible for the Pacific Northwest

Wind warnings extend across the entire Oregon coast, where gusts can reach up to 75 mph. This raises concerns about felled trees, power outages and possible dangers along Interstate 5.

Record-breaking impacts of forest fires are also increasing the threat of flooding in Oregon. According to the Oregon Forestry Department, more than 1 million acres burned. These scars from burns that remain make the threat of flooding even greater, due to the carbonized soil and without vegetation to absorb rainwater. This increases the possibility of flash floods and landslides due to loose terrain.

The culprit

The climatic phenomenon that causes all this rain is called the atmospheric river. They are basically rivers of high humidity in the atmosphere. They carry abundant moisture from tropical regions and release it to other areas in the form of rain or snow.

According to NOAA: “These vapor columns move with the climate, carrying an amount of water vapor approximately equivalent to the average flow of water at the mouth of the Mississippi River.”

Not all atmospheric rivers are bad. Often, they carry very beneficial rain for areas that need it. Many areas along the West Coast will have 30% -50% of their annual rainfall in just a few of these events.

However, with a stronger event, it can lead to dangerous floods and life-threatening landslides. The atmospheric river that stretches from Hawaii to the West Coast was coined as “Pineapple Express” and is one of the most well-known atmospheric rivers.
A December 2019 study published by researchers at the Scripps Institution of Oceanography suggests that, over the past 40 years, atmospheric rivers have posed a $ 1.1 billion flood risk for each of those years along the west coast.

This river with a particular atmosphere is 2,700 miles long with a target in the northwest. This is equivalent to the distance from Seattle to Miami in a straight line, and the humidity it carries can put January 2021 in the record books.

Hurricane hunters arrive on the West Coast

This atmospheric event on the river is so significant that hurricane hunters will be flying through it, launching buoys.

“To really understand how significant an atmospheric event on a river will be, you need to get close to it. Hurricane hunters fly inside them and collect valuable data that meteorologists use to determine how a given atmospheric river will affect the Pacific coast region. “says CNN meteorologist Allison Chinchar.

This is the second flight of the season and something they do regularly.

“The Hurricane Hunters started flying in atmospheric rivers for the first time in February 2016 and have been sending 6 to 12 flights from January to March since then. It is not uncommon for them to be flying at this event, although it is a popular misconception that as soon as the hurricane season winds die, so does your role, “says Javaheri.

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