June 08, 2011

Why we suffer with low clouds

Take a look at the visible satellite picture today and something strikes you: most of the eastern Pacific is covered with clouds! The majority of these are shallow stratus or stratocumulus clouds found within the lower few thousand feet.

During this time of the year the atmospheric structure of the eastern Pacific is often characterized by a relatively shallow moist layer, with dry air overhead. Want to see a sample of this? Here is the sounding of temperature, wind, and dewpoint at Forks on the WA coast. Such soundings are produced by launching radiosondes--instrumented weather balloons. Remember when the temperature (red line) and the dewpoint (blue line) are close together, the air is saturated (100% relative humidity). The height is in pressure (1000 mb is near sea level, 900 mb is around 3000 ft). Temperature is in centigrade.You see that the low-level air is moist and saturated in the lower few thousand feet and very dry aloft. In fact, capping the moist layer there is a very stable layer--an inversion where temperature increases with height. Want to know why we are so persistently cloudy during late spring and early summer?---blame that moist layer and inversion!

Now why do we get this infernal atmospheric structure? Ironically, it is due to high pressure over the eastern Pacific this time of the year! Here is the pressure pattern this morning (Wednesday) at 5 AM. You see the big high? That is the culprit. High pressure areas produce sinking motion, particularly on their eastern sides. The sinking decreases towards the surface (since air can't do through it). Sinking produces warming. Thus, there is more warming aloft. That produces a an inversion or stable layer! Think of it this way....warm, less dense air, with cold denser air below does not like to mix, since the cold air is heavier. With a stable atmosphere there is not a lot of mixing, so the lowest portion of the atmosphere in contact with the ocean get moister and moister...and you can imagine what that produces....low clouds.

So high pressure gives us June gloom, Juneuary, or tomato hell...whatever your favorite terms for this dismal situation is. But you can escape it! The marine air is shallow and doesn't get across the Cascades...so head over the pass and you can enjoy sun and warmth...that is what I did last week when I went mountain-biking near Thorp with a friend.

But take a look at that satellite image again..you see the really clear area over the northern CA coast? What causes that? Any meteorologist worth his/her salt knows---offshore flow. If you look at the surface map above (which also has low level winds, click to make big) you will note the pressure lines (isobars) and winds suggest an offshore component of the wind across northern CA...those offshore winds are driving warm, dry continental air over the ocean, producing the clearing.

It looks like we are going into a period of absolutely boring weather. A lot of days with low clouds in the morning, some sunbreaks, temperatures near or bit below normal in general. But no tornadoes, windstorms, wildfires, flooding, or anything that will distract us from complaining about the low clouds. And you may have to start watering your garden.

Other news:

I will try another videopodcast Friday morning to replace my KUOW segment.

I left a detailed commentary about the KUOW situation at:

And PLEASE, will someone run for the district one Seattle School Board position against Peter Maier! Many of us really are hoping that we can turn the Seattle school district around, but we have to replace a few of the poor members that allowed things to get so bad.


  1. "Centigrade?" What's that? Why don't you use an SI unit?


  2. Care to comment?

    Seattle Residents Exposed to 10 Radioactive "Hot Particles" Per Day


  3. I just received the following message from KUOW in response to my email complaint about Cliff's firing:
    We appreciate you taking the time to send us an email regarding Weekday and Cliff Mass. I’ve attached a letter here from our Program Director, Jeff Hansen, concerning the program changes with the weather segment on Weekday. You can also find a Q&A and letter from the Board on our website. I hope that you’ll find them useful.

    Thank you for your support of public radio, it makes all of KUOW’s programming possible.

    Matt Albertson
    Membership Services Coordinator

    June 2, 2011

    Dear Listeners,

    At KUOW, our audience is our greatest single resource. We value your intelligence, your passion, your commitment and your curiosity.

    Our programming attempts to inform, inspire, challenge and touch you. We listen to and value every voice. And we believe the reason that you come to KUOW is because we stand for something. You come to us because we attempt to be fair and balanced, and to reflect the complexities of the world in an intelligent way.

    So for us, the way we program the station is not done through a series of random acts. There are rules that we follow, and there are standards of behavior that we expect of our guests.

    For a long time, Cliff Mass has been a valued contributor to KUOW. His knowledge and passion about the weather is something that we have appreciated, and that a portion of our audience has appreciated as well. But as is probably clear to most of you by now, we have not had the easiest of relationships.

    Over the years, Cliff has wanted greater freedom to say more on a variety of topics and was often bothered by the limitations of the weekend weather segment. Until recently, Cliff has also been involved in a lawsuit against the Seattle School District over their adoption of their current math curriculum.

    Given this involvement in that litigation we felt it was even more important that Cliff not stray into that very controversial territory during his regular weekly appearances.

    There was a 2 1/2 hour face–to–face meeting between KUOW producers and Professor Mass to try to resolve the issue, and there was an agreement for a time. But now we find ourselves back to square one.

    In the last few weeks, Cliff has made some fairly serious accusations against KUOW. He has written that the decision to drop him from "Weekday" is "ominous and disturbing." He has accused the station of being deceptive, and he has insinuated that our programming decisions are being dictated by the "local education orthodoxy" at the University of Washington, the institution which holds KUOW's license.

    This is strong language, and it does not sound like it is coming from a person who either respects KUOW or who wants to continue to have a relationship with the station. Cliff says there are other places that have asked him to become a weekly guest and that would welcome his wide ranging comments on other topics. That sounds like it would be a better fit for him all around.

    We will absolutely consider inviting Cliff back to be a guest on other shows, if for example, we were to put together an hour on science or math education. But for now, our decision not to book Cliff on a weather segment stands.

    To Cliff's fans, we're really sorry we couldn't make this work. For us it comes down to principle. We will not cede our programming decisions to any guest, even one as popular as Cliff. That's where we draw the line.

    Jeff Hansen
    Program Director

  4. I believe "radiosonde" refers to the essentially disposable instrumentation package, not to the balloon, nor to the combination of instrumentation and vehicle.

    The radiosonde is most often returned to earth via parachute after the balloon ruptures; if you find a radiosonde on the ground, there's likely no balloon anywhere near it.

    Also, one of my favorite words.

  5. Why do most weather plots/graphs lack axis labels and units? It makes interpreting graphs like this one nearly impossible to the newcomer:


    To be perfectly honest, this has been a major pet peeve. And since It's finals season on campus, if one of my students gave me a figure lacking a key/axis labels/units, I'd say this would lose at least 1/2 credit.

  6. Just got an email from Washington Online Weather's Michael Fagen - seems KUOW has hired him to do the weekend weather segment.

  7. Regarding the statement from KUOW's Jeff Hansen: he really said nothing other than they want to control what is said on their station - is that what "Public Radio" is - censorship? The man clearly needs a course in 'debate' to offer up some real meat on this other than the 'souse meat' he gave.

  8. Cliff,

    Not all of your admirers can access facebook. Will you be posting the same info you reference about the KUOW situation on this blog?


  9. Just received: KUOW is going to have Michael Fagin on Friday at 9:45 to forecast the weather and give hiking suggestions. He has a weather web page: http://www.wowweather.com/

    I've gone to a talk he gave on the weather. I'm not sure what his qualifications are, but he's definitely no Cliff Mass!

  10. Michael Fagin's probably an OK guy, and it seems many people find his mountain weather forecasts useful. However, he has nowhere near the credentials that Cliff does, and I have to admit, I'm strongly biased against anyone who has major misspellings on their home page! Here are his credentials, as he posted them on Washington Online Weather. I note NO degree, just advanced coursework in Cliff's program.

    Michael Fagin

    Weather forecasting for the major expedition groups that climb Mt. Everest and other major climbing venues.
    Lead forecaster for West Coast Weather, LLC dba Washington Online Weather.
    Mountain weather forecasting for leaders of the Seattle Mountaineers.
    Forecasting for the entire Western U.S.
    Climate data analysis

    University of Washington. Upper level courses in Atmospheric Sciences.
    Workshops and seminars through the AMS

    American Meteorological Society, associate member.
    Past president of the Puget Sound Chapter, American Meteorological Society
    National Weather Association member

    "Best Rain Shadow Hikes: Western Washington". Book on mountain weather and on hikes.
    "Washington Online Weather". Publishes mountain weather web site

  11. All,
    Michael Fagin is a very nice guy, but he is not a meteorologist and doesn't have a degree in the field. A very interested amateur, who sat in my weather forecasting class...cliff

  12. Anne,
    I will do a major blog about the KUOW situation in a few days which will summarize what is going on....thanks for being interested..cliff

  13. Cliff, are you going to help him out by posting updates to the blog Thursday night and/or by posting your video blog early enough Friday for him to cadge from it? Poor guy, there's no way he can compete.

    And there are several regular commenters on the blog here that can probably also formulate a reasonable weekend forecast on Friday morning. Not excited to listen to them on KUOW either. I want to learn the HOW and WHY that you so often provided.


  14. I told my tomato plants to go take a hike! (Over the pass, that is.)

  15. "And PLEASE, will someone run for the district one Seattle School Board position against Peter Maier! Many of us really are hoping that we can turn the Seattle school district around, but we have to replace a few of the poor members that allowed things to get so bad."


  16. I'm seriously missing my weekend weather update here Cliff .... I hope you can continue to post your videos here. Thanks!


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

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