A major storm swept across the US north-west, battering the region with strong winds and rain, causing widespread power outages, closing schools and downing trees that killed at least two people.
The Weather Prediction Center issued excessive rainfall risks through Friday, and hurricane-force wind warnings were in effect as the strongest atmospheric river – a large plume of moisture – that California and the Pacific north-west has seen this season overwhelmed the region. The storm system that hit starting Tuesday is considered a “bomb cyclone,” which occurs when a cyclone intensifies rapidly.
Crews were working to restore power to over 650,000 people on Wednesday evening in Washington state. An estimated 100,000 people were without power in British Columbia, as well as 24,000 in northern California.
Falling trees struck homes and littered roads across western Washington. A woman was killed on Tuesday when a tree fell on a homeless encampment in Lynnwood, north of Seattle, local fire department officials said on social media. A second woman was killed near Seattle when a tree fell on her home, Bellevue fire officials said. Two people were injured when a tree fell on their trailer in Maple Valley, south-east of Seattle.
The storm is expected to range for days, unleashing snow, with blizzard and avalanche warnings in the mountains, and hurricane force winds over the region. The intensity of the storm, measured by its minimum central air pressure, was consistent with a category 4 hurricane, the Washington Post reported.
Conditions known as an atmospheric river are also expected to extend from Hawaii to California. Atmospheric rivers are exactly what they sound like. These long streams of overhead moisture – or as the National Oceanic and Atmospheric Association (Noaa) says, the “rivers in the sky” – have delivered both destructive and drought-reducing downpours with alarming intensity.
What is an atmospheric river? And other weather terms explained
Here's a short breakdown of the different kinds of storms that have lashed the west coast of North America this winter.
Atmospheric river
The National Oceanic and Atmospheric Administration refers to these as “rivers in the sky” for good reason. Characterized by long streams of moisture in the atmosphere, the average atmospheric river carries an amount of water vapor that rivals the flow at the mouth of the mighty Mississippi River – and strong ones can hold up to 15 times that amount. That moisture is released as rain or snow when ARs make landfall and typically are accompanied by strong, gusty winds adding to their destructive tendencies.
Pineapple express
These particularly strong atmospheric rivers are named for their origin. Pulling moisture from the Pacific around Hawaii, Pineapple Express storms have been known to unleash torrents of precipitation when they reach the west coast of the US and Canada – and have dumped roughly 5in of rain on California in a single day, according to the National Ocean Service.
Bomb cyclone
These low-pressure storm systems help create atmospheric rivers, pushing them from the Pacific to the coast. Unlike hurricanes or other storms where the center is the strongest, bomb cyclones can generate the worst weather at their edges.
El Niño
This is a climate pattern characterized by unusually warm surface ocean temperatures in the tropical Pacific. Along with its counterpart La Niña – which, in turn, refers to a period of colder-than-average sea surface temperatures – these patterns can impact weather around the world. While the weather doesn’t always align, El Niño is associated with warmer temperatures, and generally delivers drier conditions in the northern US and Canada, and wetter ones – bringing increased flood risks – through the south.
– Gabrielle Canon, US climate and extreme weather correspondent
A low-pressure system, which has helped spur the storm and whip up winds, intensified so quickly it is considered a “bomb cyclone”, explained Richard Bann, a meteorologist with the National Weather Service weather prediction center.
The fire department in Bellevue, Washington, urged people to stay inside on the lowest floor of their homes and away from windows. An Amtrak train was also involved in a collision outside of Seattle and CNN obtained videos of downed trees on power lines.
“Travel could be very difficult to impossible. Strong winds could cause extensive damage to trees and power lines,” the National Weather Service in Seattle posted in a warning.
The storm is expected to slowly travel south and stall over northern California in the next few days. On Friday, rainfall could reach up to 20in (500mm) in parts of south-western Oregon and northern California.
On the east coast, New York City is under its first drought warning in more than 20 years. New York City’s reservoirs are at about 60% capacity, but are usually above 79% capacity at this time of year, Rohit Aggarwala, the commissioner of the city’s department of environmental protection, told NBC News. Over the last 10 weeks, the city has had 8.23in less rain than is typical for the period.
The New York City area is expected to see some rain from Wednesday night through Friday that could total up to 3in. Experts say that will not be enough to overcome the severe drought, but hope it could slow the fires.
“We hope it will be enough to wet dry leaves and pine needles that fuel these fires,” Bill Goodman, a meteorologist for the National Weather Service told the New York Times. “But we’ll just have to see what happens, and take it one storm at a time.”
The fires come as scientists warn that the climate crisis is causing more extreme weather events. Hot air causes more water to evaporate from the earth and can cause extreme flooding. But when the conditions are not there for rain, the water evaporating creates more dry conditions that can dry out the ground.
The Jennings Creek wildfire in New Jersey and New York has affected more than 5,000 acres of land, and more than 160 homes were ordered to evacuate.
The New York fire department has established a brush fire taskforce after they saw 300 brush fires over 18 days, according to ABC7. In a typical year, the department sees half that number. Firefighters put out a brushfire in Highbridge Park in upper Manhattan on Tuesday that burned through 10-15 acres of brush.
Reuters contributed to this report
