December 22, 2010

Perspective on the Winter So Far

Real Northwest winter starts roughly the first week of November and roughly ends the last week of February, so we are now approximately midway. Congratulations! By real winter, I mean the period we typically get serious weather...the big windstorms, rainstorms, flooding, snow events, etc. Yes, I can be cloudy and grungy into June, but if you look at any of the statistics, we rarely get the big stuff after March 1. And as I noted in an earlier blog, the peak of bad weather ON AVERAGE is behind us and ON AVERAGE we start drying out slightly in December. But beware of averages.

So midway, how has the winter panned out? Has the La Nina connection worked out the way we expected so far? The media has been talking about the "wacky" weather and California is experiencing flooding and heavy rains. Lets stand back for a second and review.

Here is the departure of precipitation from normal over the last sixty days. Green and blues are above normal. Bottom line: most of the West Coast has been wetter than normal by 2-8 inches, with the most anomalous wetness over the Sierras of California. In fact, Los Angeles is on track to have their wettest December on record. Is this pattern consistent with La Nina?...not exactly. During La Nina years the NW is usually wetter than normal and central CA is drier than normal. So, the California wetness was not expected. But keep in mind that the La Nina/El Nino correlation to West Coast weather is really only about probabilities....the wet north, dry south pattern is more probable....but other things CAN happen.

Here is the same map for departure of average temperature from normal for the same 60-day period. Temperatures generally near normal. This is what we expect for the first part of La Nina winter...the colder than normal temps generally occur after the New Year. But we have had some short periods of warmer and cooler than normal temperatures.

What about snowpack? Over Washington we are at or a bit BELOW normal right now (see map), and as you go south the snowpack is decidedly above normal..roughly 120% in Oregon and over 200% in the Sierras. California needs all the water it can get, those poor devils! Based on La Nina conditions we would expect the Northwest snowpack to zoom well above normal during the next two months....but again, this is a statistical correlation, not an exact prediction.

Next, here is a plot of temperature at Seattle Tacoma Airport since Nov 1, including the average high and low temperatures. Well above normal in early November and below normal for that week in November. Since then we have been very near normal most of the time, perhaps a bit above normal. Average the whole winter, nothing unusual! You can see how deceiving long-period averages are....we had record highs for a short while and record lows at other times and the seasonal average will be near normal.
And here is the cumulative precipitation at Sea Tac for the same period. Roughly two inches above normal. Long periods of light precipitation, with a big hit earlier in December when we had the flooding.

Has this early winter been wacky and unusual? Not particularly. Pretty much every year there are storms and floods and daily records. Sign of global warming? No reason to think so.

Finally, thanks for all your positive statements from my last blog. Most of you are wonderful and respectful, but there is a very small minority whose comments, both on this blog and in separate emails, range from the bizarre to the mildly threatening.


  1. Do you have any comments on weather Europe is experiencing. I remember hearing a couple of months ago that they were predicting a record cold winter over there & that prediction seems to be coming true. Any thoughts on causes for this?

  2. I so much appreciate this blog. I so would love to have been in the weather business...except for the math, physics and really difficult classroom work. Appreciate all that you do!

  3. Cliff, love your blog and appreciate the regular stats and insight you bring, today's included. Not sure why anyone would be negative in any way towards you are the info. put forth on this blog. If this were a political blog, I could understand, but weather insights??? My only encouragement is that you blog daily! Your regular updates during the Nov. snow event, in particular, were excellent and much appreciated. Long range insights would also be nice. BTW, why are you up blogging at 5am during winter break??? ;)

  4. I've been wondering what the statistics show for how this winter has panned out so far compared to previous ones. Mostly because just through casual observation it does not appear to be turning into the *Disaster* that the local media had hyped it to be - but without actual statistics it's hard to know if that is just in my little pocket of the area or an all over the region reality.

    As for nasty comments on blogs, well, like bullies in the schoolyard there are just some people who will comment nasty things no matter what is written.

  5. Hi Cliff,
    Just remember that ON AVERAGE people who reply to blogs are normal! But with no filter on intelligence, interest, or social skills, those missing the necessary skills to interact with people in everyday life find that they have an outlet on blogs like yours.

    Keep up the good work, your posts are way ABOVE AVERAGE in content, civility and interest.

    Oh since this post has no actual relation to weather, don't approve it. Just wanted to let you know that I appreciate your blogs.

  6. Dear Cliff - Love your Blog, I use it to plan my life! I'm very concerned about the lack of snow in Seattle this winter. Can't something be done?
    We offered animal sacrifices in the form of BBQ Salmon right before Thanksgiving, and look what happened.
    Here's my plan - it's a well established scientific fact that my wife's butt is 5 degrees below freezing right when she gets into bed at night. (it soon heats up to the surface temp of Venus, so don't worry.) A statical sampling of my friends indicated that ALL of their wives had the same condition! By extrapolation, most Women in the world have the same heat-sucking anatomy. If we could ask them to expose just the effective part to the sky, right before bed, for just a few minutes each night, would that lower global tempatures enough to induce more snowfall in Seattle?
    The phenomenon occurs every day, regardless of what time we go to bed. Taken world-wide, it could be very powerful.

  7. Cliff,
    I could hardly be more grateful for your work on this blog. It is compelling to me as a weather buff and science enthusiast, and a ton of fun. I also respect your "other" views on math education. Pay no mind to folks who can't distinguish between the purpose of this blog and the NWS.

    Please keep up the great writing and education you provide here!

  8. This entry is exactly why I read your blog. I actually created an account just to encourage you to keep up the good work. Robt Reed is on to something. I will try and convince my wife to give it a shot tonight.

  9. I just came from Seattle to visit family in San Diego, and Oh My! was it raining last night! It was very interesting because in the PNW, our weather seems so dynamic - even driving around town you will experience different weather in, for example, ballard than in bothell (now you know my commute). But when I got to So.Cal last night, it was just *raining* - hard, everywhere, relentlessly. I drove 40 minutes from the airport without even a slight deviation in the amount of rain. It was striking, and so different from back home.
    {Is "showers" the term for traveling rain that hits different areas intermittently?}
    I just wanted to share! It has stopped raining this morning, and I can see blue sky off in the west. Can't wait to get home, though.

  10. The Seattle NWS came out with a brief year in review article. It was good.

    Keep it going, you were a great professor and have a great book. I most appreciate your post storm reviews. What happened, how it happened, and any crazy observations. You've taught us in this blog how to create our own forecast so we'll stop complaining.

    We've had a wildly benign, most snow without receiving snow here on the lower Eslopes. Approx. 20 days of physical snowfall already! I can recount the days last EL Nino on one hand! But the thing is, 18 days ranged from trace to 1" so we don't have much snow on the ground but we will have a White Christmas!!!

  11. It is rather interesting to note how similar this winter has been to the La Nina winter of 1955-56 so far.That winter featured extraordinarily strong arctic outbreaks in the middle of November and February. However, the December and January period was uneventful;it had pretty much normal temps with above normal precip.And also there was record rainfall and major flooding in (northern) California that December, too.It appears that the anomalous blocking high pressure ridge in the Bering Sea is disappearing, and that we will soon be in a more typical zonal flow lasting until at least mid January, which should ensure more uneventful, perhaps wet,weather here.So the 1955-56 parallel should continue.I`m waiting to see whether we experience the coldest and possibly snowiest weather of this winter in the late January and February period like in 1956, and also some other past La Nina years.If not,then this winter may have to be considered another "bust" La Nina, like the 1999-2000 winter.

  12. Just don't get why some folks would need to comment in a disrespectful and threatening way. I appreciate your blog, although I live in Portland I do regularly check in to see what's happening up North (I am a Washingtonian at heart, having lived most of my life there) and what you have to say about our Oregon weather. Happy Holidays to you.

  13. "the peak of bad weather ON AVERAGE is behind us and ON AVERAGE"

    How is that calculated? Does the criteria for bad weather only include rainfall, or are other factors such as temperature, snowfall, and wind speed accounted for? It's my personal feeling that the peak of bad weather is right around Christmas, considering all of the above criteria. I would also add that the short amount of daylight at this time of the year, while not technically weather, means less sunlight.

  14. Thanks, Cliff. Always a pleasure. As one who has lived in the NW for 60 of my 62 years (with a sidebar to the interesting weather of tropical South Vietnam - Mekong delta, rubber plantations, and jungle) I can say, as objectively as my amateur scientific interest is allowed to by my inherent subjectivity, that this winter doesn't really standout much.

    The winters that I remember best are the one of 1955-56 (first grade), and 1968-69 (should have been a sophomore in college). The former I once in awhile spent trudging to school buses that never showed up because of snow (YA!!!) and the latter I spent trudging on marches, under wire, drilling, and to firing ranges at Fort Lewis (overall still much better than what followed).

    Personally, I admit a bias for wet and cloudy, windy and brisk, and against drought. The NW suits me.

    Thanks Cliff.

  15. Cliff, I am a avid reader of your blog and appreciate the effort you put in to write it. I love how you explain complex information so that the average person can understand and gain valuable information on NW weather.
    Keep up the good work!

  16. Just wanted to convey how much I apprecaite this blog and that I recognize the work that goes into creating it. This blog is part of my daily reading and you have taught me much about the Science of meteorology.

    As for negative comments, as always with subjective data, remember to throw out the lows and the highs :)

  17. brrader asked "Do you have any comments on weather Europe is experiencing."

    There was a nice piece on one of the national news sources, I forget which one (maybe USA Today?) which said that strong high pressure had parked over the North Atlantic and was diverting the jet stream, which normally brings milder weather to mid-Europe, into two streams, one going north and one going south. The northern stream allowed cold arctic air to flow down into Europe which would normally be staying up there. There was a graphic showing that both north and south of central Europe were warmer than normal, and Europe was getting the brunt of that arctic air being allowed to flow in without restraint.

    I'm no meteorologist, but this made sense to me.

  18. Update: here's the story I alluded to about the reasons for Europe's horrible very bad no good winter.

    Or if that doesn't come through okay, here's the TinyURL version:

  19. I check this blog regularly but not to get the basic weather forecast. Really appreciate the extras you deliver. You have a knack for putting the complex stuff into language regular folk can understand. Keep it up!

  20. Love the blog and the great graphics you present here. I'm a bit curious about the quick statement regarding global warming at the end of this last post. Why even draw conclusions on such a large scale change after discussing patterns from this winter, only a 60 day period? If you're trying to judge if your kid is becoming ill, would you interpret the first half a breath you see him draw in the morning and conclude how me might be getting ill over the day??

  21. Cliff,

    Did you ever get the information you were looking for RE: Olympic National Park Science Coordinator?

    Just checking. Let me know if I can be of assistance.


  22. Dr. Mass-

    You might refer your users to the main atmospheric science website for more weather data.

    merry "wet" Christmas

    Bert Wyman

  23. Merry Christmas, Cliff, and thank you for all your hard work. We appreciate it very much.

    As for the mean comments - my dad used to say: "The world needs a certain number of a^&holes - it's like the law of thermodynamics."

  24. Snow lovers are getting excited about the chance of lowland snow coming back next Wednesday night and Thursday morning.


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

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