Why are weather forecasts wrong?
Answers
hey mate!
The science of weather forecasting falls to public scrutiny every single day. When the forecast is correct, we rarely comment, but we are often quick to complain when the forecast is wrong. Are we ever likely to achieve a perfect forecast that is accurate to the hour?
There are many steps involved in preparing a weather forecast. It begins its life as a global “snapshot” of the atmosphere at a given time, mapped onto a three-dimensional grid of points that span the entire globe and stretch from the surface to the stratosphere (and sometimes higher).
Using a supercomputer and a sophisticated model that describes the behaviour of the atmosphere with physics equations, this snapshot is then stepped forward in time, producing many terabytes of raw forecast data. It then falls to human forecasters to interpret the data and turn it into a meaningful forecast that is broadcast to the public.
The whether in the weather
Forecasting the weather is a huge challenge. For a start, we are attempting to predict something that is inherently unpredictable. The atmosphere is a chaotic system – a small change in the state of the atmosphere in one location can have remarkable consequences over time elsewhere, which was analogised by one scientist as the so-called butterfly effect.
Any error that develops in a forecast will rapidly grow and cause further errors on a larger scale. And since we have to make many assumptions when modelling the atmosphere, it becomes clear how easily forecast errors can develop. For a perfect forecast, we would need to remove every single error.
Forecast skill has been improving. Modern forecasts are certainly much more reliable than they were before the supercomputer era. The UK’s earliest published forecasts date back to 1861, when Royal Navy officer and keen meteorologist Robert Fitzroy began publishing forecasts in The Times.
His methods involved drawing weather charts using observations from a small number of locations and making predictions based on how the weather evolved in the past when the charts were similar. But his forecasts were often wrong, and the press were usually quick to criticise.
METEOROLOGY attracts criticism and jokes like few professions. Sometimes, research supports the humour. One study found that when television meteorologists in Kansas predicted that there was a 100% chance of rain, it didn’t rain at all one-third of the time. And there is much anecdotal evidence for forecasters’ unreliability. In 2009, heavy rains dampened a “barbecue summer” prediction by Britain’s Met office. In January last year American meteorologists apologised profusely on Twitter for predicting a “crippling” and “historic” blizzard that never arrived.
