Weather watchers forecast better forecasts

Brian Farrell, the Robert P. Burden Professor of Meteorology, is spearheading a project that is part of a five-year initiative funded by the National Science Foundation and the Office of Naval Research to spark progress in the general area of predictability of the atmosphere and oceans. "Right now we have a fairly good forecast out to 48 hours," Farrell says, "maybe two or three days. After that, you never know." The reason for this, he adds, is that starting out with a certain amount of error is inevitable. Both the observational data and the mathematical model used to parse it are imperfect; the necessity of using them together only compounds the problem. "In order to use the observations accurately," Farrell says, "you have to know very accurately what are the errors the model is making. Because if you put an observation in, it tells you that you should make a correction in the model. But it has a little error of its own." The trick is knowing which is more right in any given situation -- the model or the observation. Helping forecasters to know whether to trust the model or the observation is the task that Farrell set for himself.