Long-range weather forecasts are based in part on past records of wind, rainfall, sunshine, and temperature. But they also use surface conditions of the earth.
- Step 1: Use the current and forecast sea surface temperatures to run computer-based atmospheric models. The models will predict surface air temperature and precipitation patterns.
- Step 2: Supplement your forecast with a purely statistical one if you have a well defined climate event, such as El Nino, to work with. Then don't forget to take your umbrella with you.
- FACT: The Farmer's Almanac bases its long-range weather forecasts on the position of the planets, tidal action, and sunspots.
- TIP: Dynamical models relate physical properties, for example, sea surface temperature and precipitation, by mathematical equations. Statistical models look at probabilities based on such trends as weather patterns over the past few years.
- Step 3: Predict sea surface anomalies for the coming 3-month season and for the 3-month season that follows it based on the observed anomalies and a combination of dynamical and statistical models.
- TIP: The most important surface condition affecting climate is the sea surface temperature. Others are soil wetness and snow cover.
- Step 4: Observe anomalies in the sea surface temperature in a part of the ocean that influences the part of the world you are interested in. For example, look at the Pacific Ocean for North America.
- Step 5: Recognize that slowly changing conditions at the earth's surface can influence climate. When the sea surface temperature is higher than normal, it usually remains that way for several months and can affect weather patterns.