Powerful Saturday Storm Headed For Already Wet Seattle Could Make History

Oct 14, 2016

Wet, stormy weather pounded Western Washington Friday morning, with heavy rain and winds gusting from 20- 30 mph in the Puget Sound region, taking out power for several thousand residents, especially along the coast. Oregon was hit even harder.  

“We have a double-barreled low pressure system going through right now,” said knkx weather expert Cliff Mass early Friday. “The weaker one went through last night.”

He says the first wave of wind was “nothing” compared to what’s ahead.

Stronger Wind, More Rain Friday

“The primary low is coming through this afternoon, north of us,” Mass said. “Starting around lunch time, the winds are going to pick up.”

He says those winds will likely be stronger, with gusts reaching 30-40 mph and maybe even a few higher gusts near the water.

The rain has been intense too and it won’t be letting up anytime soon, Mass said.

“It’s been raining a lot. We’ve had 4-6 inches in the mountains and 1-2 inches in the lowlands,” he said. “And we’re going to double that before these events are over.”

Main Event: Saturday Night

As intense as Friday’s weather has been, Mass says it’s just a dress rehearsal for what’s ahead.

“The main concern is what’s going to happen later on Saturday,” he said.  “A powerful storm is going to move up the coast.”

He says it’s the remnants of a typhoon off Asia, called Songda, “which has traveled thousands of miles across the Pacific, retaining some of its inner-core characteristics and with a lot of moisture.”

Mass says that system will start revving up right off the Oregon coast sometime early on Saturday morning. Then it will follow a trajectory that’s “almost ideal to give us wind storms here in Puget Sound.”

He says people in the Puget Sound should expect the strongest winds around dinnertime, with the peak coming sometime between 10 p.m. and midnight. Sunday morning it will still be around, but weakening.

‘Perfect Track’ Means Potential For Historic Winds

The lowest pressure area of Saturday’s storm will move up the coast and then cross the northwest tip of the Olympic Peninsula, then move across Victoria into Canada.

And that measure – how low the pressure registers – is the key comparison meteorologists are looking to as they gage the potential for a historic event.

“This storm is going to be relatively deep,” Mass said. “The potential pressure is forecast to be around 967 millibars. That’s pretty deep – that’s a stronger storm than the Hanukkah Eve Storm or the Inauguration Day Storm , the last two major storms we had here.”  

Mass also says the way this storm is revving up toward the end of its track makes it more dangerous.

“The track is almost perfect, so right now, everything we have available to us, our models, suggest that this is a real threat,” he said.

Forecast Models Now Agree

Mass says up till Thursday, the two primary computer forecast models meteorologists use were in disagreement about which track the storm would take.

“The American GFS model and the vaunted European Center model, which is normally the better model, they didn’t agree,” Mass said.

The European Center had the low going over Seattle or maybe a bit south, while the U.S. model showed a much stronger storm – as strong as the 1962 Columbus Day Storm – but farther off shore.

Mass says they’ve now come together with a solution “somewhere in the middle.”  

“Now they’ve come together to have this intermediate but very powerful storm that’s moving on practically the ideal track,” Mass said. “So our confidence in the forecast is much much higher today than it was only two days ago.”

Saturday’s Storm Weaker Than 1962, But Still Very Powerful

Mass says the storm coming through Saturday won’t be as strong as the notorious Columbus Day Storm, but he expects it will still be one for the record books.

“We’re talking about a storm that probably in the same ballpark as the Hanukah Eve Storm in 2006 that caused hundreds of millions of dollars of damage and 14 lives lost,” Mass said. “So, this could be a powerful storm.”

But Mass says there is still some room for error in the forecasts, so it might not be quite that bad.

“If it goes a little further north or further south than forecast, which could happen, that will change the winds over Puget Sound,” he said. “But right now we know the storm is dangerous and we have to watch it carefully.”

He says in particular, it’s wise to stay away from trees if possible, since falling branches and toppling trunks are the main hazards in these kinds of events.

If the lingering uncertainty about the storm seems strange, given all the technology available, Mass says take a moment to consider exactly what the computers are modeling.

“We have a storm that is starting off of Asia, it’s moving thousands and thousands of miles, over days. So can you imagine?  We have to get the track right to tens of miles; we have to get the intensity right to a few percent. It’s amazing we can even attempt to do this kind of work,” he said.

To hear the forecast and discussion of what could make Saturday’s storm historic, you can click on the “play” icon at the top of this post.The weekly knkx feature 'Weather with Cliff Mass’ airs every Friday at 9 a.m. immediately following ‘BirdNote’, and twice on Friday afternoons during ‘All Things Considered’. The feature is hosted by knkx environment reporter Bellamy Pailthorp. Cliff Mass is a University of Washington professor of atmospheric sciences, a renowned Seattle weather prognosticator, and a popular weather blogger. You can also subscribe to a podcast of ‘Weather with Cliff Mass’ shows.