I suppose that the first correct forecast that was acted upon was the great flood for which Noah built his ark and successfully survived forty days torrential rain and the consequent flood.
There have been numerous other instances when correct forecasts have saved the day and indeed may have even influenced world events. One such case was on the 6 June 1944. The British Forecaster Group Captain Stagg, of the Met. Office, correctly forecast a short window of opportunity for the allied troops to cross the English Channel and successfully start the liberation of Western Europe. The German forecasters, on the other side of the Channel, missed the small ridge of high pressure and advised the German High Command that an invasion at the time would be impossible.
But before we condemn the German forecasters, what did they have to help them in their predictions? Actually very little compared with the forecasters of today.
The art of weather forecasting advanced in great leaps during the 20th century. One of the first major steps forward was around the first world war and just after when Vilhelm Bjerknes, and a group of Norwegian meteorologists developed the Norwegian Frontal Theory. This is still the basis of out weather forecasting of today.
Whenever you watch the television weather forecast on the BBC you will see Atlantic pressure maps with weather fronts drawn on. These fronts mark the boundaries between air which has originated in different areas so brings different types of weather. And a weather front is just simply an area of cloud and rain.
Weather forecasting made another enormous leap forward on 4 April 1960 when the USA launched the first (TIROS) weather satellite and sent cloud pictures back to the weather forecasters. And what a job it was deciding what part of the earth was being photographed. Soon afterwards some satellites were put into an orbit on the equator and stayed in the same place relative to the Earth's rotation, thus enabling the forecasters to derive time sequences of the cloud patterns.
Around the same time computers were being developed, and although very slow and cumbersome at first, rapidly expanded in their ability to assimilate global weather data and process it in a numerical form which was impossible for the human to even attempt.
In fact numerical modeling to derive forecasts were discussed as long ago as the 1920s by a British scientist L.P.Richardson. He gathered a group of mathematicians to solve his equations to get the first numerically derived weather forecast. Apparently it took several days to produce a forecast for just twenty-four hours ahead, and I believe they got the forecast wrong, but at least he proved it could be done but had to wait another forty years for computers to be invented.
Most forecasts now are made by computers who take in global three dimensional weather observations and, by solving some relatively simple equations, give the forecaster maps of how the atmosphere will change up to ten days ahead.
Changes are still being made to make forecasting more reliable. In the next few years ensemble forecasting to give the probability of certain weather events happening will, I am sure, become more and more part of the daily weather forecast.
Related Links:
- Weather Basics - Forecasting
- Ensemble Forecasts
