Wimpy winter weather followed by a near-record dry spell this summer created one of the top 10 driest Rogue Valley water years on record, and the prospect of a warm and dry El Nino pattern doesn’t bode well for parched reservoirs.
The 11.47 inches of rain measured at the Medford airport in the 12 months ending Sept. 30 — the end of the official water year — was the ninth driest of all time and the most parched since the 2000-01 drought, according to the National Weather Service office in Medford.
The rain total was 6.88 inches below the 18.35-inch average, or almost one-third less than normal over more than 100 years of measurements here, according to the weather service.
The lack of precipitation has left key irrigation reservoirs in the South Cascades at or near their lowest levels heading into the rain and snow season.
Hyatt Lake was listed Friday at 4 percent full, the lowest on record and its surface elevation is 2 feet lower than in the 2014-15 drought, according to the federal Bureau of Reclamation. Hyatt’s sister reservoir, Howard Prairie, was the South Cascades’ best at 35 percent of capacity.
And forecasters say not to expect any particularly wet or snowy Christmas presents.
The federal Climate Prediction Center has forecast El Nino conditions now through December, calling for above-normal temperatures and below-normal precipitation in the Pacific Northwest.
“It’s so early, but so far it sure doesn’t look great,” said hydrologist Julie Koeberle of the Oregon Snow Survey program of the Natural Resources Conservation Service.
“El Nino normally equates to warmer and drier conditions in the Pacific Northwest, but in other years we’ve seen it not follow the rules,” Koeberle said. “We can hope for the best.”
Koeberle said November and early December rains are key after a drought year to saturate soils and set the stage for storing more water in the ensuing snowpack.
The water year started Oct. 1, 2017, with normal rainfall measurements in October and November, but just over 2 inches of rain fell from Dec. 1 through late February — a stretch that generates 8 inches of precipitation in normal years, weather service statistics show.
“That’s our wheelhouse,” said Marc Spilde, a weather service meteorologist in Medford. “Two inches of rain in that time period is a vast deficit.”
After somewhat normal spring rains, the valley was hit with what became the fifth-worst dry spell since the weather service started logging rainfall data in 1911.
June 17 started a 103-day run during which there was no measurable precipitation above 0.01 inches at the Medford airport, which is one of the valley’s drier spots. Only the July 15 thunder and lightning storm that ignited 145 wildfires in Jackson County came with measurable rain in that stretch, and that measured just 0.01 inch, statistics show.
“It was insane how many days in a row without rain, but it wasn’t a record,” Spilde said.
The record was 114 days at or under the 0.01-inch threshold in 1921.
Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or firstname.lastname@example.org. Follow him on Twitter at www.twitter.com/MTwriterFreeman.