October 31, 2013

Major Blow On Saturday

 Storm Update at 10 PM Friday..

(Special announcement at the bottom of this blog.)

If you were thinking of raking the leaves tomorrow, don't.

If you were considering an outdoor activity on Saturday, find a good movie.

Winds are coming on Saturday...yes, with some rain as well.  And something else, something white.

The models are all pretty much in agreement: a strong low pressure center will swing across southern Vancouver Island and then across southern B.C. on Saturday, with some serious wind and rain for the region. Here is the UW WRF model forecast for sea level pressure (solid lines), winds (barbs), and temperature (shading) for 5 AM Saturday.  An elongated low center is just offshore, with very large pressure differences behind it.

 Nine hours later the low is centered over Vancouver, BC with a very large pressure gradient over western Washington and the coastal waters...these will bring big winds, gusting to 50-70 mph along the coast and 30-60 mph over inland areas.

The sustained wind forecasts are shown below (gusts are stronger).   At 5 AM, when the low is still offshore, the strongest winds (30 knots and more) will be along the coast and the inland waters of western Washington.

By 11 AM, sustained winds of 35-40 knots will dominate the coast and winds in the interior (like Seattle) will greatly strengthen....stronger along the water.

 But the real excitement will occur as the low moves to the northeast (5 PM).  Winds along the coast will strengthen and a strong westerly wind surge will move eastward down the Strait, raking northern Whidbey Island, with sustained winds of around 40 kts.

Here is a chart of the predicted gusts at that time.  Impressive--60 kt gusts over the eastern Strait.  Expect some power outages on Whidbey and along the coast.

This system will be a wet one.  For example, the 24-h totals ending 5 AM on Sunday reach 2-5 inches of liquid water on the highest peaks, and 1-2 inches of water on most of the windward slopes. 
 But a lot of that water will not fall as rain in the mountains, but SNOW.  Lots of snow.
This will be the first big snow event in the Cascades this season--the predicted 24-h snow totals ending 5 AM on Sunday are over a foot in favored locations.

The first major wind/rain/snowstorm of the season...its been about time.  Enjoy.

Announcement Ivar's Mukilteo Landing restaurant (my favorite weather-themed eating establishment) will have a special dinner and a presentation (by me) to commemorate the tenth anniversary of the on storm that destroyed the restaurant in 2003.  It will take place next Thursday, November 7.  More information here.  Limited to 40 people.

Seattle Residents:   Please consider voting for Sue Peters for School Board. Check out my previous blog for more information. 


  1. Now is when I should be at my in law's time share at long beach

  2. Heh...so much for my hike to Granite Mountain on Saturday.

  3. I see that the National Buoy Center has deferred all maintenance until further notice. I also see that buoys off our coast are no functioning. How does this impact the work of meteorologists in the region not having this data source?

  4. Sounds like fun! lol I'll be traveling in the Columbia Gorge to The Dalles tomorrow. I surely hope to see some of that impressive weather--but it varies, of course, in that part of the world. Thanks for your posts!

  5. oh boy..... Could you give us a game time forecast for the Sounders conference semi-final against Portland, 7pm Saturday at Century-Link field? Or maybe I can do that myself - wet and windy!!! (Go Sounders)

  6. I live right smack on the west side of whidbey. So I guess I will be taking down my hanging baskets today!

  7. We're planning a flag football game mid day Saturday in Seattle. We don't mind wind or wet ground, but falling rain would be a bummer. The latest GFS 4km run shows rainshadowing over Seattle with 0 rain from daybreak till after sunset. Why does the NWS graphical forecast and hourly weather graph (focused on 2pm i.e. not the whole day) show 100% chance of precip? Seems like postfrontal Olympic rainshadow in Seattle (followed eventually by a convergence zone) is relatively common and not difficult to predict given strong west winds at the mid level. It seems like 100% chance of rain vs dry all day is a pretty important difference in sensible weather for the region's biggest city.


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