Jet stream pushes storm to north

Clark County dodged the brunt of a storm that caused widespread flooding across Western Washington on Wednesday.

The storm that roared through Washington dumped 5.79 inches on Cougar and 2.34 inches on Kelso from 4 p.m. Tuesday to 10 a.m. Wednesday.

Only 0.27 of an inch fell at Vancouver’s Pearson Field during that same 18-hour period.

“We expected the bull’s-eye of rainfall to be farther north, across Western Washington,” said Chris Collins, a forecaster with the National Weather Service in Portland.

Credit the jet stream with keeping much of Clark County reasonably dry while Western Washington struggled under a deluge.

“The jet stream directs storms to different locations on the coast,” Collins said. “High pressure, low pressure, those follow the jet stream. So the jet stream is the main player here.”

Collins said it’s not uncommon for higher elevations to receive heavier rainfall when they are at the edge of a major storm.

For example, Battle Ground recorded .44 of an inch of rain during the 24-hour period ending at 5 p.m. Wednesday. Yacolt, only about four miles to the northeast, received 1.81 inches, more than four times as much.

Rain in the Portland-Vancouver area was expected to increase Wednesday night and into this morning, tapering to showers tonight.

“We certainly will quiet down as the day wears on,” Collins said. “This whole system will be sliding to our east.”

Collins said he wouldn’t be surprised if this storm dumps as much as 10 inches of rain on Cougar, a Cowlitz County town about 20 miles northeast of Woodland.

With heavy rains and low-level snowmelt comes the threat of flooding. Pacific Power increased water spillage from Merwin Dam on Wednesday, causing the National Weather Service to predict the Lewis River to reach levels that will exceed the 1996 flood.

“We do have a flood warning for small streams in urban areas,” Collins said. “Because this heavy rain will shift back over us.”

No flooding is expected along the Columbia River, which was at 11.32 feet in Vancouver on Wednesday afternoon.

“Certainly we are on the rise,” Collins said late Wednesday afternoon. “We are scheduled to go up just a touch below 14 (feet) by tomorrow at this time.”

That’s still below flood stage of 16 feet — and considerably below the 1996 flood, when the Columbia crested at 27.15 feet.

“The difference between this and the ’96 type of flood is the ’96 flood involved more of our rivers,” Collins said.