An atmospheric river storm raged across the Pacific Northwest on Sunday, bringing several days of heavy rain that likely ended wildfire season in many areas and provided a small respite to a region suffering from extreme drought.
Nearly an inch of rain fell in the Seattle area in 24 hours, according to Dev McMillian, a meteorologist with the National Weather Service. The rain comes just a few days later The city utility asked 1.5 million customers to save water as its supply declined due to drought across the region.
According to a forecast from the US state of Oregon, flash flooding is possible near the Oregon-California border Center for Western Water and Extremes. Because the drought in the Pacific Northwest is so severe, the center is not forecasting river flooding.
According to the U.S. Drought Monitor, more than 43% of Washington state was in “severe drought” or worse. In Oregon, 27% of the state qualified for this category.
Several days of persistent rain are expected to end wildfire season in the western part of both states, said Matthew Dehr, a meteorologist with the Washington Department of Natural Resources’ fire division.
“It’s a pretty big feeling of relief,” Dehr said. “This will negate the likelihood of large wood fires in Washington that cause our major smoke events.”
In August, several wildfires broke out near the city of Spokane in extremely dry and windy conditions, killing two people and burning hundreds of homes.
Dehr said a tragic wildfire season could have been far worse. Fire danger reached its highest level in history in parts of the North Cascades and Olympic Mountains because the landscape was so parched.
“It was actually a powder keg ready to go, and we just got lucky,” Dehr said, adding that there were relatively few lightning strikes that started fires this year.
Dehr said grass fires could occur in the northwest of the country in October, but the risk was greatly reduced by this storm.
The rainfall should help ease the drought, Dehr said, but forecasters remain concerned, especially as an El Niño winter approaches. The El Nino pattern is associated with dry winters in the Pacific Northwest and has contributed to poor snowpacks in the past.
Atmospheric rivers are plumes of moisture that originate in the tropics. They often extend thousands of miles across the Pacific Ocean and can cause extreme weather events in California, Oregon and Washington.
Climate change is increasing the impact of these storms because a warmer atmosphere can hold and transport a greater amount of water vapor. Last winter, California was hit by a series of more than a dozen atmospheric river storms that caused landslides and extreme flooding.
The Center for Western Water and Extremeswhich closely tracks atmospheric rivers, forecast the series of storms as a Category 4 storm. Category 4 storms are considered extreme and are expected to create dangerous conditions with positive impacts on water supplies.