Record-Breaking, Hurricane-Force Storm to Approach Pacific Northwest

 FastCast—Friday, Oct. 22 to Sunday, Oct. 24: 

Most of Western Washington has picked up 0.4-0.8 inches of rain since late Thursday. A break in the rain is expected through from late Friday to very early Saturday. By Saturday morning, expect a cold front to move through, with 0.1-0.25” of rain and winds up to 25 mph. Showers are expected through the day Saturday. The next front arrives on Sunday, with up to 0.5” of rain by Sunday evening. On Sunday, an incredible storm will approach the Pacific Northwest, forecast to have the deepest pressure ever recorded in our regional waters, equivalent to the pressure of a Category 3 hurricane. The storm will weaken as it moves toward land late Sunday into Monday, and its track is very uncertain. It is expected that winds will gust 50-60 mph north of Everett and on the Coast, as well as 35-50 mph near the Cascade gaps. Timing of winds is expected to be from midday Sunday into Monday, but even that is still uncertain. Stay tuned for more information regarding this storm!

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Continue reading the full blog below!

On Sunday, a hurricane force low pressure system is expected to move near the Pacific Northwest. 

This storm, forecast to deepen to 940-947 millibars, will likely be the deepest storm ever in Pacific Northwest waters. (For comparison, the previous deepest storm in our region was around 950 millibars). Below is the European (Euro) model forecast for the storm’s peak at 11 AM Sunday.

This is where the uncertainty comes in to play, as the storm weakens on its approach to land. The Euro is bringing the storm ashore on Northern Vancouver Island around 976 millibars. However, the GFS (American) model weakens the storm to 987 millibars and moves it ashore as a weak storm near Central Vancouver Island. 

What is certain is that the storm will generate massive waves on the coast, with up to 35 foot waves and tidal overflow up to 1 foot.

For more information about the storm, visit Cliff Mass’s weather blog & podcast:

https://cliffmass.blogspot.com/2021/10/update-on-strongest-coastal-cyclone-in.html?m=1

Due to the incredible strength of the low pressure offshore, strong gap winds are likely on Sunday. Forecasts indicate gusts of 35-55+ mph in foothill communities such as North Bend and Enumclaw. These gap winds could cause E-SE gusts of 25-35 mph in the metro area as well. My graphic below shows how winds blow through the Cascade gaps.

The E-SE gap winds will shift to southerly winds as the storm moves north. 

As of Friday evening, High Wind Watches have been posted for areas north of Everett and on the Washington Coast. Gusts up to 60 mph are possible in those areas. In the interior, the forecast largely depends on the placement of the storm. It’s a safe bet to have gusts of 30-40 mph at times from Sunday to late Monday, potentially in to Tuesday. Beyond that, we’ll have to wait and see what the forecast models predict.

The other aspect of the upcoming weather is rain. A front moving through on Saturday will bring up to 0.25” to most of the region, more on the coast and in the mountains. More rain arrives Sunday, up to 0.5”. 

Below is the UW forecast for total rain through 5 AM Monday.

Expect 0.3-0.75” all along Puget Sound. 1-3 inches are possible on the coast and in the mountains.

This is far from the end of the rain, and an additional 2+ inches are possible by the end of next week.

I will try my best to have an update by 10 PM Sunday, but my home is currently under an internet outage, so that’s not a guarantee.

Stay tuned for more information about the major storm offshore. More details will come into focus as we get closer to Sunday.