YAKIMA, Wash. -- Temperatures may be dropping as fall settles on the Yakima Valley, but climate forecasters say we could be looking at a warmer-than-average winter.
El Niño might warm the Pacific Ocean this winter, which would mean a warmer, possibly drier winter than usual for the area.
“Right now, we’re in a neutral position, which means sea surface temperatures in the equatorial Pacific are normal,” said Karin Bumbaco, assistant state climatologist. “But it is pointing to a development of an El Niño by winter.”
The U.S. Bureau of Reclamation is keeping an eye on the weather as well as reservoir levels, which can be affected by the weather system.
An El Niño occurs when ocean temperatures off South America warm up in the winter. The phenomena gets its name — Spanish for “The Christ Child” — because it occurs around December. The warm water can disrupt weather patterns as a result.
For the Pacific Northwest, El Niño usually means warmer-than-normal temperatures and below-average precipitation.
Yakima typically averages 2 feet of snow a year, with nearly 9 inches of rain, while winter temperatures usually average in the low- to mid-30s, according to data from the National Drought Mitigation Center.
The drought that happened in 2015 was during an El Niño cycle, said Chris Lynch, a hydraulic engineer with the Bureau of Reclamation’s Yakima Field Office.
Forecast data from the National Weather Service shows that there is a 40 percent chance that temperatures between now and December will be above normal, with the likelihood going up to the 53-54 percent range during winter.
Bumbaco said El Niño may not necessarily affect early season snowfall, which ski resorts depend on, but it has the possibility of cutting into the late-season snow, which helps build up the snowpack and the reservoirs for the coming year.
And with this year’s dry summer, Bumbaco said it can be a concern as there might not be sufficient carryover for the next year.
Bureau of Reclamation data shows that Rimrock Lake is 30 percent full, with Bumping Lake at 24 percent capacity. Water storage is 97 percent of average, according to daily status reports for the Yakima Project.
Lynch said the agency is waiting to see how things develop.
“We pay attention to the snow, and the development of reservoirs,” Lynch said. “We’ve kind of learned that even if it is an El Niño, we might get normal or close to normal precipitation.”
He said the bureau monitors rainfall, snowpack and reservoir levels to determine how much water needs to be held back from streamflow.