Can You Predict the Weather?
- 11.21.2008
- Article Number: 2
| Think better weather forecasting requires a degree in meteorology? Maybe a degree in statistical analysis would help more. Here is a new way to forecast the weather with more accuracy and less knowledge.
February 2, 2007 - Canon City, Colorado. I brought in my Canon City Daily Record from the porch when it arrived, at about 3 in the afternoon. I opened the newspaper to the page with the weather forecast, wondering how cold it would be the following day.
The projected high temperature was 13 degrees Fahrenheit. I knew this was way too low. Forecasts on television and on the internet said that we would reach 23 or 27 degrees the following day. I knew they were also too low, and I told my wife it would be in the 30s at least. The actual high temperature the next day was 53 degrees Fahrenheit.
By the way, that's not a typo. The weather forecasting "experts" were off by as much as 40 degrees - and that was for a simple 24-hour forecast. How could they be so far off? And how could I be better than them at forecasting the weather?
I can't really answer the first question. Weather here is more unpredictable than in most places I've been. And perhaps they follow there computer models too slavishly, even when their experience and intuition tell them to adjust the forecast.
I can answer the second question. I did better than them because they were so consistent in the way they made their errors. Around this time, I remember counting something like 15 out of 20 days when all the various weather forecasts predicted a high temperature that was 5 degrees or more too low. All I had to do was take the highest temperature forecast and add five degrees.
A New Forecasting Model
The consistency in their errors was the key to this. They weren't forecasting too high one day and too low the next. They were wrong in the same ways over and over.
I'm not sure if the errors are as consistent in other parts of the country, but that could be determined by looking at the statistics. Check the forecast highs and lows for the last 365 days, and check the actual temperatures for those days. See what the predicted probabilities of rain or snow were, and what actually happened.
Let's suppose that of the 24 last times a given forecaster predicted a 50% chance of rain, it actually rained 18 times. He may have the best data, but he may be too conservative in how he uses it. Suppose this was not a fluke - which can be determined by doing more statistical analysis. You could know nothing about weather forecasting and provide a more accurate forecast simply by saying "A 75% chance of rain tomorrow" every time he said there was a 50% chance, right?
This is the basis for my new forecasting model. You start by gathering the statistical information on the forecasts of several weather forecasting services or meteorologists. You compare this to the actual weather that happened, and look for any consistencies in the inaccuracies. Then you create a computer program. As you enter each of these forecasts into it, they are adjusted for known tendencies. The result is a more accurate forecast.
For example, if Forecaster A has managed over the last year to forecast a high that averages 4 degrees over the actual high, the computer adjusts for that. More sophisticated analysis might show that Forecaster
B is consistently predicting a higher probability of rain than there is in the fall, but a lower probability of rain than there actually is in the spring. The computer can take this into account. Finally, it may work best if the adjusted forecasts of three or more sources are then averaged.
There is no need to know anything at all about weather forecasting for this to work. It is based on the idea that even when experts have all the best knowledge and data, they sometimes apply it incorrectly, and do so in consistent ways. Don't be surprised if soon some television stations get rid of their meteorologists and take advantage of this new weather forecasting idea.
"And now, your electronic weather forecast, from our Statistical Analysis Weather Machine." |
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How El Nino and La Nina affect U.S. storms
- 10.14.2008
- Article Number: 1
| El Niño and La Niña, the two extremes of the ocean-atmosphere cycle known as the El Niño-Southern Oscillation (ENSO), have a dramatic effect on world weather patterns.
Scientists track the El Niño-Southern Oscillation by watching the temperature of the surface waters of the central and eastern tropical Pacific Ocean. Under normal conditions, easterly trade winds push the warmest surface water of the equatorial Pacific into the western part of the ocean. This westward movement of surface waters allows cold, nutrient-rich water to move from the ocean floor to the surface along the western coast of South America.
During an El Niño event, water temperatures in the central and eastern equatorial Pacific tend to be warmer than normal for an extended period of time — typically at least three to five months. Reduced upwelling can adversely affect local bird and fish populations off the coasts of Ecuador and Peru.
La Niña is sometimes referred to as the "cold phase" of the El Niño-Southern Oscillation, as surface waters in the central and eastern equatorial Pacific tend to be cooler than normal.
Thunderstorms transport heat and moisture from the surface to the upper reaches of the troposphere. The location of thunderstorms across the Pacific basin during El Niño and La Niña events can then influence the west-to-east winds high above the Earth, known as jet streams.
El Niño and La Niña can have noticeable weather impacts in the USA, which vary from season to season. A strong El Niño can result in a stormy winter along the West Coast, a wet winter across the South, and a warmer-than average winter for parts of the North.
During La Niña winters, significant cold-air outbreaks can be more frequent across the northern tier of the USA, while the southern states experience less storminess and precipitation. In the eastern USA, during a La Niñ winter, there are generally fewer coastal storms and more Alberta Clippers than normal.
ALBERTA CLIPPERS: Winter storms that streak across the northern states
In the summer and fall, La Niña can influence hurricane development, often resulting in fewer eastern Pacific hurricanes and more Atlantic hurricanes. El Niño can have the opposite effect, resulting in more eastern Pacific hurricanes and fewer Atlantic hurricanes.
The Climate Prediction Center in Camp Springs, Md., expects that that neither El Niño nor La Niña conditions will dominate through the end of 2008. This "ENSO-neutral pattern" may persist into Spring 2009.
By Bob Swanson and Adrienne Lewis, USA TODAY |
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Updated : Tue, 06 Jan 2009 09:37:01 GMT
AP - Want to hear Cameron Crowe's thoughts on winning an Oscar or see how king-sized movie posters are assembled? How about a sneak peek at some of the exclusive exhibitions held at the film academy's Beverly Hills headquarters?
Publ.Date : Tue, 06 Jan 2009 08:32:50 GMT
AP - President-elect Barack Obama's selection of an old White House hand to head the CIA shows a preference for a strong manager over an intelligence expert.
Publ.Date : Tue, 06 Jan 2009 09:40:49 GMT
AP - Anthrax mailing suspect Bruce Ivins tormented his wife with rudeness and behaved erratically in the weeks before the Army scientist took his own life by overdosing on Tylenol, according to documents released Monday.
Publ.Date : Tue, 06 Jan 2009 02:42:35 GMT
AP - The Texas Longhorns will be No. 1 on at least one ballot. It belongs to coach Mack Brown. Brown said he made up his mind after Colt McCoy hit Quan Cosby for a 26-yard touchdown with 16 seconds to play, lifting the third-ranked Longhorns to a 24-21 Fiesta Bowl victory over No. 10 Ohio State on Monday night. The stunning strike capped an 11-play, 78-yard drive that took only 1:42.
Publ.Date : Tue, 06 Jan 2009 09:11:10 GMT
Reuters - The new U.S. Congress convenes on Tuesday under pressure to deal with a worsening economy by passing a stimulus package that Barack Obama could sign into law soon after being sworn in as president.
Publ.Date : Tue, 06 Jan 2009 06:18:23 GMT
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