Wild West Coast Weekend; Possible Windstorm Saturday Evening In Valley

January 4, 2019

10:30am Friday…

I’ve mentioned numerous times this cool season has been a real dud for weather excitement, and we’re more than halfway through it.  Well now we are in early January and for the first time we have the possibility of a significant wind event or even an actual wind storm here in the western valleys of Oregon and southwest Washington.  It’s only a possibility for now, but I figure it’s my job to keep you updated!

 

What’s happening?

Models all show that two deep low pressure systems will move onto the West Coast about 24 hours apart.  Those weather forecast models have come together quite a bit this morning showing the first moving north up the Oregon/Washington coastline Saturday evening/night, then a 2nd through southern Oregon and northern California Sunday evening/night.  The first is the one we are most interested in because this could be a strong wind producer.  The second gives southern Oregon a big snowstorm and strong wind down into California but few effects in our viewing area.

Here’s a slideshow from the WRF-GFS model showing the general idea…4pm Saturday a deep low pressure area is off the southern Oregon coast, then it progresses/swings north as an elongated “dip” in the atmosphere.  By 10pm it’s up off the Washington coast.  Air rushes in to fill that “dip” and we get a strong southerly wind as the low passes by.  A “classic” wind storm setup.

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If this exact setup occurs, we’d have a brief but intense windstorm on the coastline AND in the Willamette Valley/Metro as pressure rises rapidly behind the low.  With a strong wind field overhead plus those isobars oriented directly west/east perpendicular to the valley, we would be set for a big wind event.  This is the type of setup that gives us widespread 50-65 mph gusts in the valley; we haven’t seen that for a few years.

Now it’s important to note this is the most “intense looking model”, others are a bit weaker, or have the low almost directly overhead (far less wind).  It’s still 30 hours away so we’ll see what changes with evening and Saturday AM model runs.

A good example is the morning Euro (ECMWF) model run.  It is significantly weaker with a weaker low pressure center, which is barely a center at all.  More of a wind surge coming up the valley at a later time.  It shows more like 30-45 mph gusts, what we’ve already seen this season and no big deal.

WHAT COULD CHANGE IN THE NEXT 24 HOURS?

  • If the low moves directly over the Portland Metro Area, all strong wind would be to the south = no wind storm
  • Models could decide low will be much weaker as the ECMWF does = we just get a regular breezy Saturday evening = no wind storm
  • Models hold the same course and we actually get a widespread strong southerly windstorm in the Willamette Valley, we haven’t seen that in a few years.

SHOULD I DO ANYTHING DIFFERENT BASED ON THIS OUTLOOK?

No, don’t cancel anything or alter your plans this weekend; that would be silly at this point.  Maybe have some candles/flashlights ready in case the power goes out.  Or if you live in a rural area make sure your generator is working.  That should always be the case in our November-February storm season anyway.  Other than that there’s nothing you can do to “prepare” for a wind storm.  It gets windy for a few hours and then it dies down.

SUMMARY

  1. Through 4pm Saturday nothing interesting happens, except for the usual gusty east wind developing through the Gorge and into east metro area
  2. Strong southerly wind is POSSIBLE around sunset and into the evening hours  Saturday throughout our viewing area (especially west of the Cascades) but by no means a guarantee at this point
  3. Get ready for power outages and downed trees if we do get strong wind

Stay Tuned!

 

Chief Meteorologist Mark Nelsen