A La Niña that brought a healthy snowpack to Washington has ended, but may return later this year for a another winter, the National Oceanic and Atmospheric Administration said May 13.
NOAA’s Climate Prediction Center reported that Pacific Ocean temperatures have warmed to normal and likely will stay that way through the summer.
The warming broke a link between the sea and atmosphere that had created a La Niña since last fall. La Niña winters are generally cool and wet in Washington, but are warm and dry farther south.
Forecasters at NOAA and Columbia University’s Climate Institute placed a 53% chance on La Niña prevailing again next winter, compared to 40% for neutral conditions and 7% for an El Niño.
Some past El Niño winters have led to low snowpacks and summer droughts in Washington, including in 2015. This year, the state’s La Niña-swollen snowpack has held up through a dry, but not hot, spring.
Washington Department of Ecology drought coordinator Jeff Marti said May 13 that conditions are looking favorable for irrigated farmland, but not so for unirrigated farmland.
“It’s an interesting set of conditions right now. We had a really good snowpack and still do for most of the state, but we’ve had a really dry spring, especially in the Columbia Basin,” he said.
Several weather stations in the basin had their driest April on record, following a dry March, according to the Office of the Washington State Climatologist.
The U.S. Drought Monitor last week classified 20% of Washington in a “severe drought,” the second driest of four drought categories.
Another 33% of the state is in “moderate drought,” including all of Pacific and Wahkiakum counties. In this context, “drought” doesn’t mean these places are literally bone dry, but instead that overall soil-moisture levels in the region are considerably less than normal for this time of year.
In Western Washington, parts of Clark and Cowlitz counties are in a severe drought. The dry spring, however, has made farming conditions good west of the Cascades, according to the USDA’s weekly crop report.
Drought conditions are more widespread in Central and Eastern Washington. All or portions of Adams, Benton, Columbia, Franklin, Garfield, Grant, Klickitat, Kittitas, Lincoln, Walla Walla, Whitman and Yakima counties are in severe drought.
Nevertheless, snowpacks in most basins were well above normal Thursday for this time of year, according to the Natural Resources Conservation Commission.
The U.S. Bureau of Reclamation forecasts that senior and junior water right holders in the Yakima Valley will receive their full allotments for irrigation.
Consistent with a La Niña winter, drought conditions are worse farther south.
Drought covers 91% of Oregon. Portions of Deschutes, Klamath and Lake counties, making up 3.5% of the state, are in “exceptional drought,” the worst drought category,
Drought prevails in 47% of Idaho. A small area straddling Blaine and Custer counties has developed an “extreme drought.”
Drought blanketed 94% of California. The state’s two largest reservoirs, Lake Shasta and Lake Oroville, were 48% and 41%, respectively, of average, according to the Drought Monitor.