Natalie Hanson

SACRAMENTO, Calif. (CN) — Much of the West Coast is experiencing a welcome break from years of historic drought due to an unexpected, remarkably wet winter, even as an extraordinary snowpack begins to melt.

California was the first to receive a series of strong storms starting in December, defying predictions that the winter would be another dry one. According to a new report Thursday from the National Integrated Drought Information System, parts of the Sierra Nevada, Great Basin, Utah, Arizona and western Colorado saw snow water equivalent levels reach 200% to 300% above normal – and they even set new records.

During the winter, anomalously cold temperatures were persistent and widespread, with November to March temperatures measuring among the lowest third of all years since 1895 across much of the West.

Unlike the 2021–2022 water year, in which snowfall appeared early but was scarce after early January, the strong storm train continued through mid-March. By April 1, snowpack was above normal across nearly the entire West, with few areas of snow drought.

April brought a drying and warming trend to the Southwest and above-average precipitation and cooler temperatures to Oregon and Washington, reducing some of the snowpack deficits in the Cascade Range.

However, throughout May and into early June temperatures across the Pacific Northwest and northern Rocky Mountains were above normal. May snowmelt reached record highs across many western regions.

Rapid snow loss, low winter precipitation and forecasted below-average summer runoff have renewed concerns about drought in the Pacific Northwest. Experts report that abnormal dryness and moderate drought have reappeared in western Washington and Oregon over the past three weeks.

For California, the Great Basi and the Colorado River Basin, the cool, wet and snowy year brought major drought relief after three consecutive dry years. Snowpack remains remarkably deep for mid-June in parts of the Sierra Nevada and southern Cascade Range. Observed water year runoff in these regions was above normal through early June, and the forecasts indicate above-average flows persisting throughout summer.

Most of California’s major reservoirs, with the exception of lakes Powell and Mead, have filled or are expected to fill by the end of summer. The U.S. Bureau of Reclamation reported on June 12 that Lake Powell was at 37% of capacity and Lake Mead was at 31% of capacity, with forecasted inflows into Powell at 167% of normal.

However, experts say it will take much more than one wet year to refill the two largest reservoirs in the country, after over 20 years of decreasing water levels.

El Niño conditions have already developed and are expected to gradually strengthen into winter. A stronger El Niño likely means wetter conditions in the southern U.S. and warmer conditions in the north. Scientists expect impacts from the projected transition to El Niño conditions to begin to be felt by early fall.