September 16, 2021

The Winds and the Rain. Plus, My Atmospheric Sciences 101 Class this Fall

 I have talked about the rains in my previous blogs and everything is pretty much on track.

I do not want to overhype the event:  it will be roughly the same as one of our typical vigorous winter weather systems.  

This is not a major atmospheric river event that produces flooding.   And that is particularly true because our rivers are starting at relatively low flows.  Not a major windstorm. But it will be a shock to many because we haven't experienced a real storm in a long time.

But all said and done, the water vapor satellite imagery is quite impressive this morning (see below).  A huge plume of water vapor is heading our way and is now right off the coast.

The rain sequence from the last European Center Forecast is shown below.

The accumulated precipitation through Friday a 2 PM shows the rain shield spreading over northwestern Washington

By 11 AM Saturday, the rain has really piled up, particularly over the Olympics, North Cascades the southern BC.  Roughly an inch over the lowlands and several inches in the mountains.

And by11 AM Sunday, substantial precipitation has spread into Oregon.  You note the rainshadowing to the east of the coastal mountains and Olympics.

And there will be some substantial localized winds, particularly on Friday.   As the system approaches Friday morning (11 AM shown below) strong pressure differences will drive strong winds (gusts of 40-50 mph) along the coast and over the waters of Northwest Washington, and locally winds could be even stronger.
Later during the afternoon (below), the winds will weaken in those areas and strengthen over Puget Sound, with some gusts over the water to 40-50 mph.  Some exciting ferry rides are in store.
With a lot of summer growth and leaves on the trees, there will be some branches down and scattered power outages.


Atmospheric Sciences 101

Like last year, I am teaching atmospheric sciences 101:  a general introduction to weather and climate, this fall.  You can learn more about the class on the class website.  I talk about everything from the basics of the atmosphere, to weather prediction, thunderstorms, hurricanes, and local weather to global warming and climate.

I will be teaching the class in person at the UW, but will also make it available over zoom.  Thus, folks can take it remotely.

If you are over 60, you can take the class through the ACCESS program for a very nominal charge (something like $15).   Last year I had over 125 folks do so.

So if you are a UW student looking to learn about weather or a non-student interested in the topic, I welcome you to join me this fall.


  1. Thank you as always for taking the time to do this.
    I have one question. At the end of the 4th paragraph, it reads: "A huge plume of water vapor is heading our way and is not right off the coast."
    You mean now instead of not, yes?

  2. I loved Cliff Mass’s class last year. Highly recommended!

  3. I took your class through the Access program last year and really enjoyed it. Highly recommended!!!!

  4. Kind of starting to look like a bust for a meaningful amount of rain fall for the other Western Washington,(South of Tacoma) just looking at the Sat loop it looks like to me the huge plume of water vapor is heading toward Vancouver island, the rainfall forecast for Olympia area has dwindled from 3/4 to 1" to 1/10th to a 1/4" for Friday kind of disappointing, I'm not putting my sprinklers away just yet.

    1. Now as of 9AM were down to a forecast "Less then a tenth of and inch of rain for Friday, I'm expecting some sunshine later today LOL

  5. Cliff will your classes be recorded on zoom so if I have a morning conflict I can watch the class later in the day?

  6. Hi Cliff, great podcast this week, I can tell you are excited about fall and some weather to speak of :) I noticed from around 6pm today (9/17) in N. Bend the wind became very warm, almost like someone turned on a hair dryer and I can smell faint smoke in the air. If I look on I can see the winds are blowing from the SE and converging with SW winds over Tanner, can you explain what is happening here? Im assuming there is a pressure gradient thats causing air east of the Cascades to make its way easterly and pulling in wildfire smoke from Yakima?

    Separately I was in the mountains yesterday and the fire east of Glacier Peak seemed to really rev up yesterday afternoon after 1pm after winds started to increase, hopefully the rain deluge will dampen things down later this weekend.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

Is Global Warming Causing Aircraft Turbulence to Increase?

 After the turbulence encounter by a Singapore Airlines aircraft,  there has been a slew of articles claiming that severe turbulence inciden...