We encourage your correspondence, and although we cannot print all that we receive, we will include at least one short, perhaps edited, letter per issue.

Dear WeatherZine

Regarding your article about prediction and forecast (see February 2001 WeatherZine Guest Editorial) several authors have dealt with these concepts. For example, the next issue of "La houille blanche" will publish a French version of my last article about these concepts. I will provide the abstract in English.

Title: "About some definitions of risk and its consequences for forecasting, prediction, and prevention". Abstract: "Among numerous definitions of natural risk, this article examines the most widespread. Only three definitions attract attention; the first was provided by Diderot and D'Alembert between 1751 and 1772. Later the jurists described acts of God as unforeseeable and compelling. Nowadays UNESCO defines natural risk as the intersection of natural hazard and vulnerability. Definitions provided by dictionaries or insurance companies are either inadequate or morally unacceptable and should be ignored. These three definitions address foreseeability/forecast, foretelling/prediction, and prevention. In addition, this article points out the role of historical studies in natural hazards and vulnerability."

Notions such as forecast, prediction, and prevention have been tackled by Cinna Lomnitz in "Fundamentals of earthquake predictions" (John Wiley and Sons). To proceed from forecast to prediction several questions have to be asked:

1. What is the waiting period? (When?)
2. What will be the intensity of the hazard? (How?)
3. What area will be devastated? (Where?)

The conditions for achieving a true prediction are rarely met.

— Lucien Coste
Risk and environment attache (retired)
Senior lecturer in natural risks
Saint Etienne National School of Mines
lcoste@asi.fr

Comments? thunder@ucar.edu

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