A December day with 0.43 inch of rain normally wouldn’t raise many eyebrows in the Northwest.
This December? Even an unspectacular rainfall total represents the exception, not the rule.
After flirting with its driest December on record, the 0.43 inch of rainfall Vancouver saw Tuesday was enough to double the monthly total so far — eclipsing the previous 26 days combined. That kicked off a more typical winter weather pattern that’s expected to keep the Portland area wet through the start of 2012.
On Wednesday, both Vancouver and Portland finally surpassed 1 inch of rain for the entire month. This week’s wet surge means the area will avoid setting a new mark for December dryness, and could even see another 2 to 4 inches of rain by this weekend, according to the National Weather Service.
“Really what we’re going to see for the next several days is pretty typical conditions,” said Andy Bryant, a hydrologist with the weather service.
The Portland-Vancouver area tallies well over 5 inches of rain in December on average. This week’s rain won’t be enough to even come close to that.
And relatively warm temperatures will do little to help an already ailing snowpack in the Cascade Mountains.
Snowpack now stands at about half of average for this time of year, Bryant said. That could mean low river flows in the spring if the pattern keeps up, he said, but there’s a lot of winter left. The La Niña weather pattern that’s characterized by wet, cool winters in the Northwest — and remains active this year, Bryant said — piled up huge mountain snowfall totals last year.
“We have three or four months of potential accumulation time,” Bryant said.
For much of December, a stubbornly persistent weather pattern pushed moisture well north of the Portland area, keeping conditions here largely cold, foggy and dry. That followed a wetter-than-usual November, which saw more than 6.5 inches of rain.
National Weather Service forecasters expect wet and windy weather in Vancouver for the rest of this week, possibly leading to flooding in places. On Wednesday, Vancouver had recorded 0.52 inch of rain as of 5 p.m.
Some small streams and creeks were expected to rise rapidly by Wednesday and Thursday, while larger rivers could respond with “significant” rises Thursday and Friday, according to a special statement from the weather service.
Stormy conditions caused at least one power outage in the Vancouver area Wednesday. A tree limb on a power line left 1,745 homes in the Salmon Creek area in the dark for just under an hour early Wednesday evening, according to Clark Public Utilities. Crews restored power by about 6:30 p.m.