May 30, 2011

Thunderstorms on the Eastern Slopes of the Cascades

With southeasterly flow aloft and modestly unstable air over eastern Washington, thunderstorms are breaking out on the eastern slopes of the Cascades right now (2 PM on Monday). This convection occurs as the lifting caused by the eastern Cascade slopes releases the convection. On days like today, the atmosphere is in a state where thunderstorms only break out where air is lifted sufficiently so that the air becomes warmer than its environment and thus buoyant (the level of free convection).

Condensation of water vapor and the release of latent heat is an important part of this destabilization process. To put it simply, the heat released by condensation of water vapor into liquid water helps provide the heat that makes the rising air parcel warmer than its environment. We all think about the cooling that occurs when water evaporates, but we often forget that warming occurs when water condenses.

I have a colleague that has a wonderful lab in which students measure the rate of warming for cold coke cans in a dry or wet environment (this works for beer cans too!). In a moist environment, where condensation occurs on the cans, the contents warm up more quickly due to the condensation! So either drink your favorite brew quickly or keep them in a dry place.

Here are some images from the UW composite radar site (multiple radar images combined) and the Camano Island radar.

Some of the showers are reaching the Cascade crest and moving over to the western slopes--lets see if they die as they descend! The lightning detection network is picking up strikes from these systems (30 minutes ending 2 PM):

KUOW Situation

Current number of signers of the petition: 4037
If you are interesting in supporting this request for them to reinstate my weather segment here is the petition site:

Current friend on the Facebook Web Page to bring back the weather segment: 2093
Facebook web site:

I sent KUOW an email proposing a compromise that many of you suggested: a weather only segment and their establishment of other periods allowing discussion of other issues.


  1. How about they just give you your own segment -- say 10 minutes when Steve can go out for a coffee or doughnut. He is pretty clearly uninterested in scientific matters.

    That is the only way that I can imagine it working at this point; it has become too personal with the interviewer.

    You can say what you want and they (management, not Steve) can decide whether to continue your segment.

  2. Cliff, There's an on-air home for you at KBCS should things not work out at KUOW.

  3. Hello Cliff

    Today (and yesterday too), I note the sunlight has a distinct reddish cast- a sure sign of high-altitude particulates. But this isn't fire season! So the only other thing I can think of is that unless there's a volcanic eruption somewhere, there is a major dust storm in Eastern Asia, or majar pollution from China (let's hope not). So- what is causing it?



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

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