Good ten-day weather forecasts are in reach—but is that the limit?by Philip Ball / January 23, 2013 / Leave a comment
Hurricane Irene crashes into Southampton, Long Island, in August 2011 (© Joe Raedle/Getty Images)
Isn’t it strange how we like to regard weather forecasting as a uniquely incompetent science—as though this subject of vital economic and social importance can attract only the most inept researchers, armed with bungling, bogus theories?
That joke, however, is wearing thin. With Britain’s, and probably the world’s, weather becoming more variable and prone to extremes, an inaccurate forecast risks more than a soggy garden party, potentially leaving us unprepared for life-threatening floods or ruined harvests.
Perhaps this new need to take forecasting seriously will eventually win it the respect it deserves. Part of the reason we love to harp on about the disastrously misplaced reassurance from Michael Fish, the BBC weatherman, is that there has been no comparable failure since. “Earlier on today,” said Fish, “apparently, a woman rang the BBC and said she heard there was a hurricane on the way; well, if you’re watching, don’t worry—there isn’t.” Hours later, the great storm of 1987 struck. As meteorologists and applied mathematicians Ian Roulstone and John Norbury point out in their account of the maths of weather prediction, Invisible in the Storm (Princeton, £24.95), the five-day forecast is, at least in western Europe, now more reliable than the three-day forecast was when the 1987 storm raged. There has been a steady improvement in accuracy over this period and, popular wisdom to the contrary, prediction has long been far superior to simply assuming that tomorrow’s weather will be the same as today’s.
Weather forecasting is hard not in the way that fundamental physics is hard. It’s not that the ideas are so abstruse, but that the basic equations are extremely tough to solve, and that lurking within them is a barrier to prediction that must defeat even the most profound mind. Weather is intrinsically unknowable more than two weeks ahead, because it is an example of a chaotic system, in which imperceptible differences in two initial states can blossom into grossly different eventual outcomes. Indeed, it was the work of the American meteorologist Edward Lorenz in the 1960s, using a set of highly simplified equations to determine patterns of atmospheric convection, that first alerted the scientific community to the notion of chaos: the inevitable divergence of all but identical initial states as they evolve over…