Vancouver’s wet January bucked El Niño trend
Most of Northwest has been drier than average this winter
Wednesday, February 3, 2010
Don’t be fooled by January’s wetter-than-normal rainfall total at Pearson Field in Vancouver: We’re still firmly in the grip of El Niño.
At 6.54 inches of precipitation for the month, Vancouver’s rainfall total was about three-quarters of an inch greater than normal. El Niño, characterized by warm sea surface temperatures in the Pacific Ocean, generally results in warmer and drier conditions in the Northwest.
In that sense, Vancouver bucked the trend.
“During an El Niño event, the storms tend to track to the south,” said Jon Lea, hydrologist with the U.S. Natural Resources Conservation Service in Portland. “And the Northwest tends to stay relatively dry.”
Vancouver’s relatively abundant January rainfall is the exception to the rule.
Seasonal snowpack is lagging way below average across the Columbia River basin as a whole. Lea said the basin’s snowpack as of Monday amounted to 70 percent of normal, according to almost 240 automated gauges spread across Washington, Oregon and Idaho.
Most of the water that drives hydroelectric turbines in the Columbia basin first clings to the mountains as snow. A healthy snowpack means more water for irrigators growing crops and juvenile salmon migrating to the ocean. It also translates to a surplus of electricity when it runs off during the late spring and summer.
So why was it so wet last month in Vancouver?
In a word: microclimates.
Portland’s official weather station recorded 4.94 inches for the month — about a tenth of an inch below normal. That station is just a couple of miles from Vancouver’s, just across the Columbia River at Portland International Airport.
Lea, who lives in the Fargher Lake area of north Clark County, recorded just over 9 inches of rain at his house — about 3 inches below average over the past 15 years.
Even so, Lea noticed it was definitely grayer than normal this month.
In Vancouver, Pearson Field recorded only four days without any precipitation at all. The regular presence of clouds seemed to warm the area like a blanket. It never dropped below freezing in Vancouver, bottoming out at 34 degrees on Jan. 10.
Lea noticed spring-like rain showers.
“It would be raining in Portland but not Vancouver,” he said. “Or, it would be pouring in Vancouver and Portland — and when I get home, the pavement was dry from Battle Ground up.”
Erik Robinson: 360-735-4551 or firstname.lastname@example.org.