First of two potent storms strikes Northwest

First of two potent storms strikes Northwest
SEATTLE - Western Washington residents awoke Monday morning to a blustery, rainy day, and the first of two storms rolled into the Pacific Northwest. Winds gusted as high as 60 mph in some spots, knocking over at least one tree and causing a few, scattered power outages.

And this just might be the rehearsal for Tuesday morning when a second storm will come barreling into the region, and fresh High Wind Warnings were reissued Monday afternoon for Tuesday.

Here are some peak gusts with the wind from overnight through the late morning:

  • Bellingham: 61 mph
  • Oak Harbor: 56 mph
  • Hoquiam: 53 mph
  • Anacortes: 52 mph
  • Alki Beach (West Seattle): 51 mph
  • Friday Harbor: 49 mph
  • Astoria, OR: 48 mph
  • Forks: 46 mph
  • Seattle: 43 mph
  • Everett: 43 mph
  • Boeing Field (Seattle): 42 mph
  • Tacoma: 38 mph

In Bellingham, Western Washington University said its campus would be closed until noon due to power outages. The city had 10 consecutive hours (and 11 of 12) of gusts higher than 40 mph, and a four hour period with gusts over 50 mph. The wind has been even more relentless at the Naval Air Station on Whidbey Island, where they have had 26 hours of gusts over 40 mph with occasional gusts over 50 mph.

The wind was strong enough to knock a tree over in Seattle's Greenwood neighborhood:

Al Noriega heard a large crack around 3 a.m. at his house in the 100 block of NW 78th Street. He went outside to find a large cedar tree had broken, sending one heavy branch across his roof. He wasn't injured.

The peak of this first storm has passed, and all wind warnings and advisories with this storm expired at noon. Winds will slowly calm through the afternoon and evening.

Meanwhile, rain will continue to fall, causing flooding on some rivers -- even some major flooding in Mason County.

Flood Warnings are now in effect for the Skokomish River, Bogachiel, and Satsop Rivers. The Skokomish is expected to have major flooding, while the other two are in the minor flooding category for now.

Flood Watches are in effect for all other rivers that feed off the Olympic Mountains, as well as rivers in Whatcom, Skagit, Snohomish, Lewis and Thurston Counties. (Lewis and Thurston are new to the list as of 10:30 a.m.)

More Wind On The Way

We'll actually get a lull now into Monday evening as the first storm passes. In fact, winds may significantly calm, but don't think the event is over. We'll still see rain at times though.

The second storm rolls in Monday night into Tuesday. However, newest forecasting models are now weakening the storm just a touch. I still get the sense it'll be on par to maybe a slight bit stronger than the one Monday morning, but if the Monday forecasting models are correct, it's not as dire as Sunday's forecast was looking.

Still, High Wind Warnings have now been reissued for the coast and Northwest Interior from 6 p.m. Monday through noon Tuesday, meaning winds with potential to be damaging are imminent. In this case, winds could gust as high as 55-60 mph -- about on par with the first storm.

A lesser Wind Advisory has been issued for the same time frame for most of the rest of Western Washington, including the greater Seattle Metro area, but excluding the greater Sequim/Port Angeles area. In the advisory areas, gusts will once again be between 40-50 mph.

We expect winds to quickly increase just after midnight Tuesday morning along the coast, and Northwest Interior a couple hours later (1-3 a.m.) reaching the Puget Sound area around daybreak.

(Update for the weather geeks. In Sundays' story, I wrote about how to put in perspective, we try to gauge wind speeds based on differences in pressure, as the greater the difference, the stronger the wind speeds. One meter is the difference in pressure between Bellingham and Portland. During typical November wind events (like we've seen a few times this month), this number usually gets around 8-10 milibars difference. The Inauguration Day storm of 1993 was a 21.5 and the Dec. 2006 storm was 23.2.

Mondays' storm peaked at 12.3. Newest forecast models have Tuesday's storm now in the same realm with the greater wind field up in southern B.C. )

Winds will calm Tuesday afternoon.

What's going on?

We have a very strong jet stream that is pointing right at the north coast and into southern B.C. and inside the jet is a very active series of storms rolling along the path. Put another way, think of the jet stream as the bowling alley, storms as bowling balls, and we stand right about where the "3" or "6" pin sits ... and Mother Nature is a fairly decent bowler.

As to why it's been so persistently windy up north and along the coast, the storm tracks have been to our northwest and north, carrying large areas of low pressure along for the ride. Air flows from higher pressure to lower pressure and so air is trying to race offshore to meet up with the lower pressure out there.

With little terrain on the coast, air flows unimpeded toward the storm, so wind speeds can get really going. As lower pressure moves north of Forks, air will also shoot out the Straits of Juan de Fuca, Georgia, and across Vancouver Island. The "Northwest Interior", as well call it, has an open path for southeasterly winds to race toward the lower pressure offshore. But for areas south of Everett, the Olympic Mountains are a big wall and prevent a southeast wind from garnering up much steam to head to the northwest. That's why it can be really windy on Whidbey Island for hours on end, but just down the road in Seattle, winds are weaker and don't last near as long.

However, once the storm center moves due north of the region, now instead of a southeast wind, we have a south wind and the Olympics are no longer a factor as the air can just race straight up the I-5 corridor. This wind also affects the Northwest Interior, so it's a double whammy for you and another reason why wind events last so much longer up there.

Flooding a concern, too

Aside from the wind, rain will be a factor in the mountains. These storms have quite a bit of moisture embedded and with the strong winds aloft slamming that moisture into the mountainsides, the process will wring out a lot of rain.

The Olympic Mountains and Northern Cascades will take the brunt of the rain, which is where the Flood Warnings and Watches are located, and lesser amounts are expected in the Central and Southern Cascades. The Green River looks like it'll be OK.

The greatest flooding threat lies on the Skokomish River, which is seeing major flooding. A Flood Warning is in effect here. The Bogachiel and Satsop are also on Flood Warning for minor flooding. Other Olympic Rivers are also under the gun for some sort of flooding.

In the Cascades, the Nooksack is probably the greatest threat to flood, although at this time not expected to be major. Rivers in Snohomish and Skagit County will get close to flood banks and might go over, but they are more uncertain.

Over on the coast, a Coastal Flood Watch is in effect Tuesday for the effects from persistent strong south winds, combined with high tide, 20-foot waves, and low atmospheric pressure to cause coastal flooding. The predicted high tide Tuesday is 11.1 feet.

Minor tidal overflow occurs around 13.5 feet, with coastal flooding in Aberdeen at 14.0 feet. These conditions are ripe to add about 2-3 feet to tide table predictions, so thus, the watch. Those along the coast should be prepared for some tidal flooding.

Rain will taper off to showers Tuesday night and Wednesday, but more rain and wind is expected Thursday. In fact, early forecast models suggest that storm could bring another round of wind on par with this storm, although it is expected to be shorter in duration.