This winter's forecast: NOAA vs. the woolly bears
The tropics are quiet again today, so let's follow up on yesterday's discussion about the long range forecast for the coming United States winter. Those of you outside the U.S. will probably be more interested in what the International Research Institute for Climate Prediction has to say for your country, and I encourage you to check out their excellent web site for their seasonal forecasts. Interestingly, they forecast that virtually the entire world will have average to much above average temperatures during the December-February period, with only two tiny pockets of slightly below-average temperatures in Australia and central Asia. This should keep the oceans at the near-record high temperatures for near year's hurricane season, helping fuel another round of more intense than usual hurricanes. In addition, El Nino is expected to remain in a near-neutral phase the next 6-9 months (same as for this year's hurricane season), which should result in a higher than usual number of tropical storms and hurricanes for 2006. Still, I don't think we'll see anything like this year's level of activity, which was a once-in-a-lifetime hurricane season. Dr. Bill Gray's team at Colorado State University issues their first forecast for the 2006 hurricane season on Tuesday, December 6, and we'll talk more about next year's season then.
As we discussed yesterday, the official woolly bear caterpillar forecast for the U.S. mid-Atlantic coast area was for a warmer than average winter. The official NOAA 90-day forecast for the upcoming winter, issued on October 20 by the Climate Prediction Center (CPC), disagrees, calling for equal chances of an above average or below average winter over the eastern half of the country, but a higher than average chance of a warmer than average winter over the western half of the country. How well has the official forecast done in recent years? NOAA rates its forecasts using the Heidke skill score, which is a measure of how well a forecast did relative to a randomly selected forecast. A score of 0 means that the forecast did no better than what would be expected by chance. A score of 100 depicts a "perfect" forecast and a score of -50 depicts the "worst possible" forecast. For the 90-day temperature forecasts issued 1.5 months in advance done in January through May of this year, the Heidke skill score was greater than zero for two of the forecasts, less than zero two of the forecasts, and about zero the other forecast. The Heidke skill score for 90-day temperature forecasts issued 1.5 months in advance has averaged 8 the past ten years (see Figure 1.) So, while there is some skill in forecasting what the winter will be like 1.5 months in advance, this skill is not much better than flipping a coin or relying on woolly bear caterpillars. Let's look at some examples from forecasts for previous winters issued at about this time of year. The 90-day forecast done in mid-October of 1999 for the winter of 2000 was awesome, with a Heidke skill score of 50. However, the 90-day forecast done in mid-October of 2000 for the winter of 2001 was horrible, with a Heidke skill score of -15.
Figure 1. Skill of the official 90-day forecasts issued 1.5 months in advance by NOAA's Climate Prediction Center. Note that the average skill is positive, but has remained flat the past ten years, indicating that our skill in making long-range forecasts has not improved.
Why do seasonal forecasts do so poorly? It's partially because our physical understanding of what controls the climate is so poor. It's also in large part due to the fact that the long-term weather is chaotic and fundamentally unpredictable by nature, and no amount of physical understanding will help us. So, pick your forecast: woolly bear, coin flip, NOAA--the three techniques have similar levels of accuracy. Or you can check out the predictions of Psychic Helane, who wrote me to say she had correctly forecast the impact of Hurricane Wilma on South Florida over one month in advance. Her winter prediction calls for "the north especially St. Paul, Minnesota and Upstate NY will see its worst winter in memory." If I were an energy futures trader, I would wait until I saw a longer track record for Helane's weather predictions. She is also calling for a "huge hurricane in Alabama" this month, which is a virtual impossibility, given that sea surface temperatures in the Gulf of Mexico are now less than 80F (26.5C), which is too cold to support a major hurricane. Go with the official NOAA forecasts, which a have a proven track record of some having a least a little skill compared to chance.
Jeff Masters
Reader Comments
Page: 1 | 2 — Blog Index
As far as the huge hurricane in Alabama in November, normally I would agree with the good doctor, but this is the season of 2005. I still think Delta and Gamma are still out there..
As for your grandmother and father, well, they are wrong. More information leads to better forecasts. No forecast will ever be perfect, of course.
And, yes, same sign blew down during Wilma...guess she is 0 and 3, and I get a laugh every time I pass that sign.
Once I dipt into the future far as human eye could see, / And I saw the Chief Forecaster, dead as any one can be - / Dead and damned and shut in Hades as a liar from his birth, / With a record of unreason seldom paralleled on earth. / While I looked he reared him solemnly, that incandescent youth, / From the coals that he'd preferred to the advantages of truth. / He cast his eyes about him and above him; then he wrote / On a slab of thin asbestos what I venture here to quote - / For I read it in the rose-light of the everlasting glow: / "Cloudy; variable winds, with local showers; cooler; snow."
It seems that in the eyes of most of the weather forcasting community Global Warming is a Fait ac compli. However, what I have always found curious is this same group (weather forcasters and climatologists) have not improved their forcasting - prediction accuracy beyond about 10 days. Dispite the aid of an ever increasing data base, more and more accurate data, satellites and the advent of powerfull computers, the forcasting abilities beyond a couple of weeks have not improved at all!
Of coarse, in observational science large scale changes (such as the proposed Global Warming) can be more obvious than mid and small scale changes. Even if you give significant weight to the potential large scale observability premise, it is still diffucult (for me) to belive or find the Global Warming predictions as credible.
If we look at past climate trends, say over the past 500 years we have seen several significant anominalies with life spans in the 20-50 year or longer range. The Maunder minimum of the late 1600's is a classic example.
What if such an event were to occur today? Would the techno crowd and politicians be forging policies to increase CO2 gasses? How about space missions to the sun designed to increase sun spot activity? Or declaring certain geographic areas as off limits?
I, am of coarse over simplifying and over stating the obvious. But if you apply the basic scientific cause - effect rules to the Global Warming predictions and assumptions it is easy to call the whole premise in to question. That is because of the near total failure in the fields of medium term weather forcasting accuracy and the very poor current understanding of long term climatology. The forcasting summary that Dr. Masters provides near the end of his blog today is amazing. Forcasting beyond a few days is no better than a flip of a coin. Think about that!
That reality is difficult to ignore. It make me really nervous to see Global Warming become a major political issue and see it accepted as truth. Caution and perspective are needed on this issue, not blind acceptance.
Dr. Masters ending comments and prediction acuracy comparisions, to me, really drive this point home. Interested in hearing comments.
Speakerman
see what my colleague Joachim Goes and his team have to say about a particular instance: http://www.bigelow.org/climatechange/.
total agreement here. i've argued this point on an individual basis and in letters to editors in local papers in response to alarmist global warming articles. i've come to the unpleasant conclusion that people have short memories and long political agendas, and rational thought is out of fashion. (another phd here, but plasma physics, not weather related).
Here's a theory: perhaps when forecasts are doing well, the forecasters tend to stick with the model (or set of models) that is working well at the time. Then, as climate patterns shift, the forecasters stick with that model too long, resulting in negative skill. Eventually the forecasters figure it out, and start relying on a different model, and the skill goes back up again. And the cycle goes on and on.
Cat 1 "You're such a wimp." Fake coat (i.e, passes for a coat in other parts
of the country), although it looks real enough.
Good for chilly days.
Cat 2 "OK, so I need a coat." It got below freezing. You'll be sorry if you
get caught waiting for a bus without this, even
though most of the time you'll be wearing it open.
Cat 3 "Oooh, it's chilly." But...it's still above zero.
Cat 4 "Bring out the down." In the minus digits, and Weatherpeople are
overemphasizing the wind chill factor.
Cat 5 "It's finally winter." The winter festival...timed to coincide with the
ten days it never gets above -15. Alternate
between that and refusing to go out (after all,
it does hurt to breathe).
I don't want to see a record winter, but I'd be happy with more good cross-country ski days than we had last year.
However I bet they wouldn't have those problems if they'd relocate to Kansas. Then they could blame delays like that as the side effects of heathen folks watching TeleTubbies. A school board there just redefined the term "science" so that "it’s not limited to the search for natural explanations of phenomena."
I'm going to encourage science teachers in kansas to start teaching that lightning is a result of Thor throwing bolts around. No need to limit ourselves to natural explanations. And who here has ever seen an "ion"?
Airlines should start charging what it actually costs to fly, then they wouldn't be going bankrupt.
No, wait...I'll leave being critial to you.
The fun stat is the one that says of the 120 years of recorded temperatures in Chicago, only about 50 days had the "average" high and low. So if the average high/low was 66/37 for today, the long-term odds of that temperature being reached today is about .10%. I personally know of one date in the last 4-5 years that was completely, totally normal.
Just an interesting fact.
See everyone tomorrow!
Bye =)
I have been lurking on this blog for a while, but am finally inspired to comment. Happy weather watching to you all!
Both are limited by lack of initial data, but more importantly, both are also limited by the chaotic nature of the processes that are being modeled.
You use three key words in your comments, "Long term Trends". That is also key point in my original comments. What is long term? The Maunder minimum lasted 60-70 years, depending on the criteria used to mark the beginning and end of that particular weather cycle. Hurricane cycles can be 30-40 years in duration. Ice ages and tropical periods and so on can persist for thousands of years.
I have been looking at sea surface anomaly temp data from the US Navy and other source for several years and can not find any consistant, long term patterns or differentials supporting sustained temp increases. I realize data averaging, detection methods, anlytical standards - algorithums and so on can distort the concluding data. Nothing is perfect.
If you take every thing all one way (in support of increasing temps) you are hard pressed to see even a 1 deg C average increase on the earths oceans during the past 50 years. The atmosphere, of coarse is far more volatile due to it being a significantly less dense media. Again, looking at the data you are hard pressed to see a 2 deg C increase and much of that,in my opinion is suspect. Satellite temp data for the last 30 years or so is so flat I wonder if the atmosphere could be that consistent.
At the risk of being overly metaphorical, true, unbiased long term evidence is thin and the jury is still out.
Caution and adherence to good science and data interpretation practices applied over a appropriate time period are absolutely essential before reasonalbe conclutsons can be made. As of now I personally do not think this criteria has been met.
I am seeing way too many folks sign on to the Global Warming theory with out having a clue as to what, if anything may be going on. As legend from the late 1920's goes, when the big money in the stock market starting getting unsolicited stock tips from elevator operators it was time to get out of the market.
Some things, particularly doom and gloom or something for nothing are easily over sold.
Speakerman
I'm feeling rather afraid that it might have been just a warm-up for what is to come. Is there any scientific reason to think this year was some kind of anomaly, given the accepted assumption that we are in for a trend of severe and frequent storms in the next couple of decades?
LpAngel.... I sure hope the de-icing doesn't stop working at -10 to -15 or us in Alaska would be homebound till Spring. The airlines still fly even at -40 and -50 below. Its a little longer process, but we still fly. I always get nervous because at those temps you see Ice on the wings, but the guys and gals do an awesome, thorough job to keep the planes ready and able to fly without incident.
Global warming? Even since I have been here in Alaska, I've seen changes in the terrain up here. The Tundra isn't so barron anymore, there is actually growth of vegetation that normally isn't there and species of sealife found in waters way further north than usual. You should see what happens when Ice Fog takes over Fairbanks. Its nothing more than emmisions from exhaust being held down to the ground by the cold above it. Its painful to breath outside and you can literally move the fog with your hands. You cant drive without having your car IM'd in the winter up here and the fine is stiff. If what we see in this small place is an example of what effect global warming is having on the planet, I can only imagine what it would be like to combine it all across the planet. I shutter to think about what it would be like in a place like Los Angeles at 30 below zero. YUCK!
- global warming from greenhouse gas emissions;
- global cooling due to the dust thrown up into the atmosphere from above ground nuclear testing
If you look at the surface temperature trends of the last 150 years you will see rising temps from the start of the industrial age through to the 1950s, a cooling trend lasting well into the 1970s, and a continuation of the warming trend since then. The cooling trend was due to the nuclear testing.
Take out that cooling effect from the bomb testing, and you have a steady rise in temps over 150 years with no end in sight. Our future climate will be very different from the one we grew up with, and many people are very concerned that it will be much less hospitable to human life.
I remember one snowstorm I was on a plane where we had to go through the deicing more than once before takeoff. That was a little unnerving. Now, luckily, I don't have to travel every week.
Are you noticing this odd little swirly low thing off the Pacific Coast west of Los Angeles? See
http://www.atmos.washington.edu/cgi-bin/latest.cgi?ir
I've been watching this all day and it looks gradually better organized and somewhat stationary. Occasionally we do get whopper storms on the Pacific Coast here in the fall and winter (Inaugural Day Storm of 1992, another one on Nov 5 1982 and the 1962 Columbus Day Storm) - thus the interest in this thing.
Casey
insignificant little mouse? hmmmm... i should take exception to that, knowing what i do about mice, but i enjoy your intelligent comments too much to be bothered by an unintended slur...
with a wink and a nod,
mouseybabe
Viewing: 1 - 51
Page: 1 | 2 — Blog Index