The outcome of D-Day was decided not on the beaches of Normandy, but by weather systems in the mid-Atlantic and the ability of rival teams of meteorologists to interpret the forces of nature. The Americans were confident in long-range five-day forecasts. The British were sceptical, believing they could forecast only two days ahead at best. The teams clashed repeatedly.
The outcome of D-Day was decided not on the beaches of Normandy, but by weather systems in the mid-Atlantic and the ability of rival teams of meteorologists to interpret the forces of nature.
As unfavourable conditions developed during that early summer 70 years ago, three teams of meteorologists produced reports for the Allied commander, General Dwight D Eisenhower, who laid down the conditions necessary for invasion — and his preferred date: June 5. Across the Channel, a single team of Germans watched the weather.
One of the men who took part in this great drama was Lawrence Hogben, a New Zealand naval officer, who, as a Rhodes Scholar, studied mathematics at New College, Oxford and trained as a meteorologist with the Royal Navy. Today, he lives in a care home in southern France, the country he helped to liberate and, even at the age of 98, retains vivid memories of events in June 1944.
Hogben had already distinguished himself as a naval officer before he was asked to work with Geoffrey Wolfe, a Cambridge-educated engineer, in the Admiralty team forecasting the D-Day weather.
As an instructor lieutenant, responsible for training, intelligence and meteorology on HMS Sheffield, he had witnessed several major naval actions: the sinking of the German battleship Bismark in May 1941; the Battle of the Barents Sea — when Sheffield engaged the German pocket battleships Admiral Hipper and Lutzow in the Arctic in December 1942; and Operation Torch, the invasion of French North Africa a year later.
Decorated for bravery and promoted instructor lieutenant-commander, he had also developed his skills as a weatherman. “OnSheffield, I was making forecasts every day from the data coming in and from the state of the sea,” he says.
Hogben and Wolfe were one of two British teams. The second, put forward by the Met Office, consisted of Charles Douglas, the chief forecaster who was known for his photographic memory of meteorological events, and Sverre Pettersen, a Norwegian. The third team was American, with Irving Krick and Benny Holzman, two well-known weathermen from the California Institute of Technology. Each day, the three teams reported their findings to Group Captain James Stagg, a Scot who had been superintendent of the Kew Gardens observatory in 1939. He briefed Eisenhower.
For operational reasons, the American commander needed a full moon, a low tide, little cloud cover and light winds so that troops in landing craft could get ashore quickly, the gliders and parachutists could operate efficiently, and the Allied fighters and bombers could find their targets.
The forecast was not good. Indeed, climatic data suggested the odds against the forecasters finding the right conditions was 13-1 in June 1944. The Americans were confident in long-range five-day forecasts. The British were sceptical, believing they could forecast only two days ahead at best. The teams clashed repeatedly.
According to William Bryant Logan, author of Air: The Restless Shaper, they succeeded, “not because of the brilliant work of any solitary forecaster, but because a group of forecasters imitated the weather. They jostled, yelled, scribbled, and cast malevolent looks at one another. They fought it out and voted. And in the end, they were just right enough.”