Windy Christmas Eve

 It's gonna get windy tomorrow. How windy? Well that's the sixty seven thousand dollar question we've all been asking.

The Setup

An area of low pressure of the California coast will begin to consolidate and strengthen over the next 12 hours. As it does so, it will be moving north towards Washington and Oregon. The exact track and strength of the low pressure system will determine the magnitude of the winds tomorrow. So let's break down all the possibilities.

1. The EURO 

The EURO has been portraying the weakest outcome for this system. The low strengthens down to the about 987 millibars, but the it moves inland over Oregon and Washington, resulting in gusts up to 45 MPH for most of the region. Windy? Sure, but nothing crazy. This would be our "run of the mill" wind event with some tree damage and scattered power outages. 


2. Historic Windstorm (NAM)

Moving on, the NAM, a mesoscale model that is used for forecasting in the US, has been portraying a particularly concerning solution. The low pressure system begins to rapidly intensify into the 970s (millibars) as it moves almost due north, hugging the Oregon and Washington coasts. It casts an intense pressure gradient over Western Oregon and Washington, bringing widespread gusts of over 60 MPH to the region. This would be an intense windstorm, the likes of which we have not witnessed here in a long time. This solution would bring widespread damage, especially due to the saturated soil. 

Now these solutions are the two extreme ends of the possibilities for tomorrow. The most likely outcome would probably be a hybrid of both solutions. I think the low will take the track that the NAM model has been showing, moving north while staying offshore. However, I highly doubt it gets as strong as modeled in the NAM. Given the significant uncertainty between the models, I would say that we will see a windstorm tomorrow with gusts up to 50-55 MPH for most of the region. Maybe even into the 60s in the Willamette Valley. The saturated nature of the soil is also concerning. Tree damage may be more widespread and frequent. The timing of these winds would be 7 AM through noon for Oregon and noon through 4 PM for Washington. Given the possibility of rapid pressure rising from this storm, winds could hit with no warning rather suddenly. 

This is a very complicated forecast. Tomorrow could end up just being a breezy day rather than strong winds. On one hand I want everyone to be prepared but on the other I don't want to sound the alarm given the high degree of uncertainty we have.

At this point I would say keep an eye on the weather, and have a plan if power goes out. Charge phones and other electronic devices. Remain aware!

NWS Seattle has a high wind watch out for the Puget sound lowlands, this will likely be upgraded to a warning soon. 

Stay safe and I will try and keep you guys updated through this!!

I will try and update 

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