January 15, 2014

Spring Warmth Arrives in the Northwest

First, the good news.  Warm air will flood over the Northwest during the next few days.   Air reminiscent of spring or summer. 

The bad news?  For many of you, this warmth will be several thousand feet away...above your heads.

Currently, a high amplitude ridge is building aloft over the eastern Pacific (see map at 500 hPa, around 18,000 ft at 4 PM Thursday).  No polar vortex worries for us!

 With strong sinking motion in the ridge and the northward movement of warm air on its western side, air temperatures aloft will soar.  To illustrate this, here are the temperatures at 850 hPa (about 5000 ft above sea level).  This is a good level to look at since it is high enough to get above most surface complications.  This sequence is from 10 PM, Tuesday evening through 1 PM on Friday.  The darker the orange/red the warmer it gets.  During the period temperatures over Seattle warm about 8C (14F).

Here are the forecast surface (2-meters) air temperatures on Thursday and Friday at 1 PM.  The warmest temperatures are over the foothills of the Cascades, along the coast and in the Willamette Valley...getting into the 60s!   Much cooler at lower elevations near the water.  But why?

We can plot the model forecasts for temperature (red) and dew point (blue) over Seattle for the next two days and see the air is drying (dew point is becoming much less than the temperature) and warming aloft, producing a strong low level inversion.  Very typical behavior when a ridge of high pressure develops overhead.  So there will be cooler air and probably fog/low clouds at very low levels, but if you go up a few thousand feet, it will get toasty.

The upper foothills will be much warmer...so take a hike up Tiger Mt. (2500 ft) near Issaquah and expect sun and warmth.  Air descending down the coastal mountains will bring warmth to the coast

And as you can expect, no additional snow.    Thankfully, this week has brought our snow pack up substantially:  to roughly 80% of normal in the North Cascades to 50% of normal near Mt. Adams.  Things rapidly worsen in Oregon to roughly one-third of normal and California Sierra Nevada is a disaster at around 25%.  They have a serious problem.

We are now back in a persistent ridge pattern, with the NOAA Climate Prediction Center going for much drier and warmer than normal over the next week (see graphics:  brown is dry, red is warm)

Fracking and Ozone

UW Professor Becky Alexander has established a page on the Microoryza crowdfunding web site that outlines her project  to understand why natural gas fracking often leads to high ozone values over snow (go here to see it). If you want to learn more about this important project and how you can help it happen, check out the web site.  Or take a look at the video below explaining the project.


  1. i've been to your friend's website about doing a fracking study.

    it says "log in with facebook" but then it just hangs. There is no way to even send her an email to let her know we can't get through. I really don't want to sign up for yet another website so i thought signing up with FB would be the way to go.

    Please let her know she is losing customers since her website is not working right.

    ps while i'm at it, i am failing your spelling test. i really am not a robot..it is more and more difficult just to communicate with hurdles like these.

  2. Understandable not to want to create YAL (Yet Another Login) but going directly through Microryza takes only an extra minute or two. Dr. Alexander is a mere few hundred dollars from completing the fundraising goal and it's an all-or-nothing deal; her team is awarded nothing if that last little bit of daylight is not crossed.

    I'm hoping I have to 'fess up. :-)

  3. "The bad news? For many of you, this warmth will be several thousand feet away...above your heads."

    Fortunately, I am very tall.

  4. Hi Cliff,

    When I lived in the East we had sunny winter days (highs?) that were often breezy. I presume that the temperature-altitude curve was therefore probably adiabatic right from sea-level... What is it about the West that makes it more prone to inversions?


  5. My corn is already a foot tall. And, the tomatoes are just starting to set...

  6. The Oregon coast has been basking in sunshine (like we often do in the late fall/winter when an inversion is in place and the Willamette Valley is socked in low clouds, fog and cold temperatures). Much of the coast in the low 60s and Brookings hit 73 today. I understand why the Cascades stay clear and warmer in an inversion (higher altitude and warmer air aloft), but why does the coast, even though not at a high elevation? Is it because of the high pressure which compresses the air and warms it up as it moves down the coast range? Either way, I'll take it!

  7. Do we get to say "w00t" on Cliff's blog?

    From Microryza:

    "Thanks to you and 153 other backers, the How does natural gas fracking contribute to air pollution? project raised $12,000 and is now fully funded."

    I suspect Cliff's promotion has helped with this. Yay, us-all!

  8. The fracking campaign has funded but there are still a few days to over-fund and help the science move along. @MimiTabby, the scientists don't own the site; it's like Kickstarter for science. I'm glad that you brought this to our attention, Cliff, though my wallet is sad that I know about a new crowdfunding site. LOL

  9. Dear Cliff,
    I base my weekend hiking plans on your forecasts! Is this inversion going to persist at least through Saturday? Would a snowshoe trek up to Camp Muir be a good idea for Saturday do you think?

  10. Will this inversion layer persist through the weekend? In other words do you recommend seeking higher altitudes for sunshine and blue skies? Maybe a snowshoe trek up to Camp Muir would be a good idea?

    We're waiting for your words of wisdom to plan our outdoor adventures this weekend!

  11. Ansel, the reason the Northwest, and in fact much of the western US, is because of the mountains around us. All of the cold air sinks down below the elevation of the Coast Range Mountains and acts like a lid keeping out any warmer air. Then, to answer Ryan's question, offshore flow or the east wind, which is common in high, comes off the warm air over the mountains and goes over top the inversion in the valleys and slides over the Coast Range and into the coastal region, usually at its warmest temperature.

  12. Thanks Jack, yes, and I note that by mid-February, highs are usually sunny- unlike now, and there is a lot less fog. I presume the somewhat more direct sunlight creates enough heat to "mix out" inversions. Here's to February...

  13. Thank you Jack Bloss. I understand that when high pressure is overhead it often creates offshore flow (east wind) but on some of the warmer, clear days here on the coast the wind is very light (albeit from the east).

    Perhaps Cliff can further explain the phenomena, but is it more likely the compressed air as it descends the coast range (that warms up as result) rather than warm air from the inversion layer above the Cascades and gets carried by the east wind that creates the sunny and warm conditions at the coast?


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

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