Baker County’s abnormally long spring dry spell likely will end this weekend.
A month has passed with no measurable rain at the Baker City Airport.
And the most recent “rainy” day scarcely deserved that adjective, as a meager 0.01 of an inch moistened the rain gauge at the airport on March 22.
That’s the smallest volume that qualifies as “measurable” by National Weather Service standards. A trace of rain fell at the airport on two days earlier in April.
The persistent weather pattern that has brought mostly clear skies, along with an awful lot of wind, to Baker County since early March will give way this weekend to a more typical — and potentially damp — spring pattern, said Jay Breidenbach, warning coordination meteorologist at the National Weather Service’s Boise office, which issues forecasts for Baker County.
A storm will move from the Pacific Ocean into Oregon with widespread rain showers, snow in the mountains and cooler temperatures, Breidenbach said.
“The pattern looks like it’s finally going to break down a little bit this weekend,” he said. “It’s not a big storm, but it should bring some moisture.”
A National Weather Service model forecast calls for about 0.21 of an inch of rain in Baker City from Saturday through Monday.
That’s more rain than has fallen here since late February. The March total at the airport was 0.14. It was the second-driest March at the airport since at least 1943, the first year for which records are available. The driest March was 1969, with a total of 0.13.
Both March and April average about 0.80 of an inch of rain.
The driest April was 2020, with a rainfall total of 0.20.
The dry spring has been a surprise, Breidenbach said. With relatively colder surface water in parts of the Pacific Ocean — what’s known as a La Nina pattern — weather typically is wetter and cooler than average in the Northwest, he said.
“Except for February it didn’t work out that way,” Breidenbach said.
Although cold fronts have frequently swept through the region since early March, the storms contained little if any precipitation.
The reason, Breidenbach said, is that the winds in the upper atmosphere, which in effect “steer” storms, have been from the north and northwest, meaning the storms travel not over the Pacific, an obviously ample source of moisture, but over land.
Storms that originate over land are much less likely to bring precipitation to Eastern Oregon and Idaho, Breidenbach said.
This weekend’s storm, by contrast, is the first in more than a month that will blow across a long fetch of the ocean, allowing it to entrain enough moisture to deliver rain and mountain snow far inland, he said.
The recent dry stretch, combined with Phillips Reservoir being well below its capacity, prompted the Baker County Board of Commissioners to approve a drought emergency declaration on April 7.
Although the mountain snowpack is above average, much of Baker County is in a moderate or severe drought as of April 13, according to the U.S. Drought Monitor.
Baker Valley is in extreme drought, the second-highest of the four levels behind only exceptional drought.
Typically the wettest period in Baker County is May and June.
May ranks as the wettest month at the Baker City Airport, with an average rainfall of 1.43 inches, and June ranks second with an average of 1.28 inches.
Those are the only two months with an average rainfall of more than one inch. The yearly average at the airport is about 10 inches.