January 25, 2009

Humility

Well, one thing a forecaster learns quckly is humility. There is a weak upper level disturbances that is causing this light precipitation. The heaviest precipitation is on the eastern side of the Sound. Take a look at the radar animation to see the details ( http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?atx_n0r+/2h/ ). The models did not handle this light precipitation well...in most of the region there is no accumulation...but some of you are getting up to around an inch (Woodinville and Snohomish seem to be ground zero for the worst). It WILL end later this afternoon and early evening....guaranteed.

Light precipitation is a clear weakness of our current models...working on this issue is definitely on my to-do list....cliff

20 comments:

  1. When I said that models weren't "rocket science," I meant that the precision isn't there.

    Models aren't precise, cannot account for every event. I have a friend who is a modeler in another industry. He says that if his error percentage is less than 10% that is purely accident. There is only so much you can model.

    The rest you have to leave to chance.

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  2. Out here on Ring Hill/East Woodinville, it is 32 F with 2" of snow on the ground and still snowing.

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  3. Science isn't science! This is just flickery and white and pretty. Besides, it's Sunday.

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  4. Here in City Center Lynnwood, it's been snowing lightly all day, temps hovering right around freezing, but there's only a trace of accumulation on cars and occasionally on bare ground. The roads are just wet, which means there might be a problem once the super-cold air gets here.

    I just looked up the King-5 online forecast, and they seem to think that the precipitation has already stopped, and that the skies are clear. Funny! I, for one, appreciate the fact that I can come here and get a more accurate forecast! Lyn in Lynnwood

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  5. Being a meteorologist is like being a Stockbroker.
    You are never faced with long periods of uninterrupted success.

    Have been do this since 1974 and my forecasts are better than my investments.
    Cheers!

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  6. If you're looking for something else to do besides mope about science and models, take a look outside. In Shoreline we have flakes a half a centimeter in diameter with six point symmetry.

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  7. It seems like the best way to avoid "humility", is to not "guarantee"!

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  8. Anonymous (at 5:51 pm) makes an interesting observation: the flakes are very symmetrical this time. I don't think I've ever seen such perfectly stereotypical snowflakes. Is there something special about the conditions which gives us these beautiful snow crystals?

    Thanks for everything Cliff!
    -- Bruce Kelley in Redmond

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  9. Bruce...I noticed that too! And they are extra sparkly! I'm in Eatonville....Usually when they say snow, we get rain....when they say no snow, we get it....It's been snowing all day...very light and almost misty until around 1:00 pm, then the flakes got bigger....The temp. never got above freezing all day (31.1 - 32)....It's 8:30 and still snowing....about 1 1/2 inches so far....school is already 2 hours late for tomorrow....I wonder how long we'll have to wait for spring to arrive this year?

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  10. Snowed lightly here all day with temp of 31, 32 degrees. The snow picked up just a tad during the afternoon hours, but became flurries by evening. Picked up a half inch of snow today here on hollywood hill.

    Right now it`s 28 with dp of 25.

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  11. Today's flakes are beautiful. I studied them in my "lab" (black jacket sleeve) this afternoon. Kenneth Libbrecht at Cal Tech has a website with a morphology diagram at http://www.its.caltech.edu/~atomic/
    snowcrystals/primer/primer.htm that might explain some of the conditions that produce different flakes. He's got a few books on the subject, too.

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  12. I'm at 850 feet on Cougar Mountain. Roads are covered with thin layer of ice. Extremely slippery.

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  13. How much snow did you get on Cougar mountain?

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  14. Wow, dendritic snowflakes here, too. I hadn't noticed, so thanks for the tip. A few years ago I took some macro photos of snowflakes that fell.

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  15. I think your models are more accurate than most! Keep 'em coming!

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  16. Thank you Liembo for passing along photos of dendtritic snowflakes. How nice to be in the company of folks who take the time to notice the special qualities of a snowflake.

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  17. Hi Cliff, you've probably already heard this but there was lots of snow on Cougar mountain, probably and inch or two on top at 1 or so and it was still snowing. I had taken your word for it that the snow would stop by afternoon and though it was a good day for a run!

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  18. Its all right Cliff. The HAL 9000 got the Fraser Valley outflow nailed yesterday up here in Bellingham

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  19. Don't you mean Woodinville and Snohomish were ground zero for the BEST?

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  20. IMHO, it boils down to psychology. Going back and doing a post-mortem we can kind of see what goes wrong: An approaching "arctic" boundary driving a wedge of cold, dry air underneath a surface layer that's still fairly moist (80-85% RH); a vort max at H500 sliding down the coast adding a little instability and there you've got some SW-. But occasionally forecasters see a dry QPF panel and, because the overall trend is toward drying and clearing, all that science in our head goes bye-bye and we get Sunday afternoon. Not a HUGE error but one that makes people think we're off our rockers. Our hearts are in the right place though.

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