Drought will worsen or develop in Oregon, Idaho and Washington over the next three months, according to the National Oceanic and Atmospheric Administration’s spring outlook issued March 16.

Waves of atmospheric rivers tracked to the south this winter, soaking California but largely missing the Northwest, according to NOAA.

California and the Great Basin should see drought conditions improve because of large snowpacks, said Ed Clark, director of NOAA’s National Water Center.

“In contrast, across the Pacific Northwest, normal to below-normal snowpack conditions lead to average to below-average water-supply forecasts,” he said.

Only 1% of Washington, the northeast corner, is in drought, the U.S. Drought Monitor reported March 16. NOAA forecasts drought will develop throughout the Cascade Range.

Some 77% of Oregon is in drought, and NOAA sees that worsening. Drought covers 76% of Idaho. NOAA forecasts drought ending in southeast Idaho, but worsening elsewhere.

NOAA forecasts that spring rains will be below-average in all of Washington, the top of the Idaho Panhandle and about half of Oregon.

By “normal,” NOAA means what was normal between 1991-2020. The trend over the past decade in the Northwest has been less rainfall, a factor in NOAA’s forecast for a dry spring.

A La Nina that reigned over the past three winters ended this month. La Ninas are linked to wet and cold winters in the northern U.S. and warm and dry winters in the southern U.S.

This past winter, the impact of La Nina was “flipped,” said John Gottschlack, operations branch chief of NOAA’s Climate Prediction Center.

An “astonishing” amount of rain and snow fell in California, he said. NOAA forecasts spring flooding in the Golden State as snow melts.

“The Pacific Northwest this year was generally drier than normal,” Gottschlack said. “A lot of the storm tracks were shifted farther south.”

The La Nina was not strong. It’s not unusual for the affects of a moderate La Nina to vary, Gottschlack said.

“In fact, if you look at moderate La Nina events over the record we having going back to 1948 or so, there is the potential for above-normal precipitation, near-normal precipitation or below-normal precipitation almost equally on the West Coast and parts of the West,” he said.

NOAA forecasts a cool spring for southeast Oregon and Idaho below the Panhandle. For Washington, California and most of Oregon, NOAA forecasts normal temperatures.

La Nina has given way to “neutral” conditions. Later in the summer, the odds favor the Pacific Ocean along the equator warming up and forming an El Nino.

El Ninos are linked to warm and dry Northwest winters, possibly worsening any drought conditions that develop before then.

Forecasters can’t be too confident in predicting an El Nino will form, Gottschlack said. “We have to wait a few more months before we’re sure we’ll go into an El Nino,” he said.