Sverre Petterssen

Sverre Petterssen
Sverre Petterssen in Norwegian uniform
Born	(1898-02-19)19 February 1898 Hadsel, Norway
Died	31 December 1974(1974-12-31) (aged 76) London, England
Residence	United States
Citizenship	United States
Nationality	Norwegian
Fields	Mathematics and Meteorology
Institutions	MIT
Alma mater	Bergen School of Meteorology
Doctoral students	James Murdoch Austin
Known for	D-Day weather forecast
Influences	Tor Bergeron

Sverre Petterssen (19 February 1898 – 31 December 1974) was a Norwegian meteorologist, prominent in the field of weather analysis and forecasting.

Born in Norway into a humble family, he paid for his higher education by working at the telegraph office, and a nursery provided by the armed forces that he joined as a recruit. He studied in Bergen where he met Tor Bergeron during a lecture, and was so impressed by his analysis of a 1922 storm that he joined the Bergen School of Meteorology in 1923. In the late 1920s he worked at the Geophysical Institute in Tromsø, northern Norway.

After school, he remained a weather officer in the Norwegian Air Force until 1939. He went to the US in 1935, lecturing on Norwegian meteorological theories to the US Navy and Caltech. In 1939, he was hired by MIT as head of the meteorology department, and wrote two important books there: Weather analysis and forecasting (1940) and Introduction to Meteorology (1941).

With the invasion of Norway, Petterssen returned to Europe and offered his services in England to the Met Office, on loan from the Norwegian Air Force. During World War II, he served as a weather forecaster for bombing raids and special operations.

He is most remembered for his work in what has been called the most significant weather forecast in history, the D-Day Forecast, where he contributed significantly to the postponement of D-day by one day. Three groups of meteorologists gave advice to General Dwight Eisenhower, and D-Day was originally planned for June 5, 1944. But he got big trouble with academically untrained competitors, especially from the United States, who believed that the weather was repeated – and had found a weather recurring pattern in the 20's that they felt was positive. And General Dwight D. Eisenhower was relying on his men. "Pettersen, which was not always as diplomatic, made it clear that this was nonsense and quasi science but Eisenhower was convinced, and the invasion would take place on 5 June. But at the morning meeting on 4 June Pettersen presented a weather map showing storm June 5th. To strong protests from the American quasi-meteorologist, D-Day was postponed.