Potential for a Major Windstorm on Friday/Saturday

There is potential for a major windstorm late Friday and early Saturday. Let's take a look at the latest information as of Tuesday evening.

As of Tuesday evening, there is still a lot of uncertainty about the impacts of this potential storm.

Here's what is more certain:

• A strong storm will make landfall on the Pacific Northwest Coast late Friday/early Saturday
• The storm will pack strong winds, but the placement and impacts of the wind are unknown
• More details will be refined in the coming days

Let's dive into the data. Below is the UW WRF forecast model for 10 PM Friday. 

See the 977 mb (millibar) low center off Vancouver Island? That is the possible major storm. The UW model brings this storm ashore in southern Vancouver Island, an ideal track for strong winds over Puget Sound.

Since winds are caused by difference in pressure, the closer the pressure lines means stronger winds. 

With this storm, the strongest winds will be found south of the low center.

Below is the forecast for 4 AM Saturday. The low center has moved northeast and is now over southern BC. Look at how tight the pressure gradient (change) is over Western WA! That signals strong winds during this time (should this forecast verify).

Of course, this is just one forecast model. A forecast is most reliable when multiple solutions are used.

The GFS (American) model brings a slightly weaker (981 mb) low into the NW tip of the Olympic Peninsula, a bit farther south of the UW model.

Below is the ECMWF (European) model, one of the most accurate forecast models. It brings a strong 975 mb low into the north-central Washington coast.

The European model also brings the storm ashore 5-10 hours ahead of the other forecasts, trending towards Friday afternoon, not late Friday night. The Euro’s landfall is on the borderline of strong winds or minimal winds over Puget Sound. Remember, the strongest winds are south of the low center, where the pressure change is strongest.

The small but significant differences in the forecasts above show that there is still uncertainty regarding what could happen.

Something you need to know is that the track of the windstorm will determine a lot about what happens. Here are the current approximate forecast model tracks.

Red is the European model. Blue is the GFS model. Purple is the UW model.

There is over 130 miles of spread between the forecasts. Far too much uncertainty to make a confident forecast.

If you were wondering:

• A landfall near the tip of the Olympic Peninsula or over Southern Vancouver Island produces the strongest winds for Puget Sound and all of Western WA
• A landfall south of the Euro model's track produces lesser winds for Puget Sound and stronger winds for Oregon and SW Washington
• A landfall north of the UW model's track produces lesser winds for Puget Sound and stronger winds north of Everett and on the coast

Also...wind speeds are still quite uncertain. As of now, I’d expect gusts in the Puget Sound area of anywhere between 35 and 65 mph. (That’s a very large spread...so nothing is for sure...but it’s always wise to be prepared).

Nothing is certain yet...but more details & forecasts will be refined in the coming days.