Scientific Forecasting Capabilities

MYTH #3: "These meteorologists, they're all just guessing. They don't really know."

Although some may still believe more in pre-scientific types of weather forecasts, including predictions far into the future, than in the ability of present-day meteorologists, predictions not based in scientific methods cannot be described as science-based predictions. Any attempt to draw conclusions about nature not based in scientific methods is by definition making use of remedial methods, as were used in the centuries that preceded the scientific revolution.

An example of a remedial method for predicting the weather is pattern analysis. It was discovered as long ago as the 19th century that pattern analysis was not an effective method for predicting the day-to-day weather. This understanding was reinforced by the advent of chaos theory in the 1960s.

Chaos theory was first proposed by a meteorologist but later expanded to include all the natural sciences; it has since found its way even into the social sciences. It puts forth an explanation for the difficulties in predicting the future states of complex systems like the weather, namely, that the future evolution of such systems is highly sensitive to the initial conditions (the values of the system's variables at the initial time). Change one small characteristic about the initial state, seemingly unimportant by itself, and the long-term outcome will likely be the evolution of the system into something vastly different from what it would otherwise have been.

Lorenz attractor

The main consequence for meteorologists and other scientists is that small errors have a way of becoming magnified as the system evolves, and that it is not long before the system achieves a state that is totally unrecognizable from what was originally predicted. Chaos theory has therefore imposed a short natural limit to weather forecasts, one that is measured in days, not weeks, months, or years.

Ancient cultures thought the weather was determined by the moods of the gods. Astrology pretended to connect the futures of human beings to the motion of celestial bodies. Modern science has taken our civilization out of the Dark Ages. It has liberated us from superstition and other subjective modes of thought by providing an objective basis for the acquisition of knowledge about the workings of nature, and for the making of predictions about its future states, albeit with a measure of uncertainty.

It is not reasonable in our post-modern 21st century world to even compare subjective weather predictions not based in the scientific method to meteorological forecasts based on advanced, objective scientific methods.

The limits of the science today are such that ten days' lead time is presently considered to be the outer limit for day-to-day weather forecasting skill. The outer limit for hurricanes is about five days. Twenty-first century hurricane track forecasts inside of three days show considerable skill and continue to improve steadily, whereas intensity forecasts demonstrate some skill through about two days. Statistical long-range forecasting efforts, such as the seasonal hurricane outlooks, are highly experimental, their skill level as yet undetermined. Those outlooks, addressed in the previous section, are based on the observed states of large-scale atmospheric phenomena that don't change much from one day to the next, but shift from one recognizable state to the next according to seasonal, annual, multiyear, or even multidecadal cycles. A very important example of such a multiyear cycle with a large-scale influence on the Atlantic hurricane environment is El Nino.

In contrast to all these weather forecasting efforts based on science, predictions about weather and climate without scientific foundations have not been shown to exhibit any skill beyond what would be expected from throwing dice.

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