Obituary: Irving Krick

Perhaps the greatest challenge ever put to weather forecasters was to advise General Dwight D. Eisenhower on the timing of the D-Day landings. Irving Krick's part in this enterprise is a piece of meteorological history.

Krick gained a doctorate in meteorology at the California Institute of Technology (Caltech), and went on to set up the meteorological department there before in 1936 establishing one of the first private weather consulting firms. By 1944 he was the head of the Weather Information Section of the United States Strategic Air Forces in Europe. The work of this section, which was responsible for all forecasts for the US forces, had to be combined with the predictions of the UK Meteorological Office and the Admiralty to produce agreed advice for the Allies. The man responsible for co-ordinating this advice was Gp Capt James Stagg.

There were only two three-day periods in June 1944 when the tides were sufficiently low to offer a good chance of negotiating the German beach defences effectively. The first was from 5 to 7 June. The Allies needed a forecast five days ahead that the weather would be sufficiently calm and clear to enable the various naval and aerial operations to proceed.

Krick had developed an analogue technique which matched current conditions to similar meteorological situations from the past 40 years, and then predicted future behaviour on the basis of these sequels. The British forecasters' work used a more basic physical approach which suggested that anything beyond 48 hours was a lottery. The dilemma for Stagg was that, while Krick's forecasts provided detail and were presented with greater confidence, the evidence at the time was that they did less well than the more cautious British efforts.

D-Day was planned for 5 June. The British and US forecasts were in disagreement as the date approached, with the latter predicting better conditions throughout the period from 5 to 7 June. By late on 3 June it was becoming clear that the weather was deteriorating, as an exceptionally deep low for the time of year, quite unlike anything seen in the previous 40 years, moved toward northern Scotland. At 4.15 am on 4 June Stagg was able to predict confidently that the weather would be too bad on 5 June and Eisenhower decided to postpone the invasion for 24 hours.

By early on 5 June all the forecasters agreed that the stormy conditions would abate by the next morning, so Eisenhower was advised that the conditions would be fit for the invasion to go ahead. The achievement of this consensus says much for Stagg's diplomatic skills, given the personalities involved, the awful volatility of British weather, and the daunting consequences of failure.

To the annoyance of many British meteorologists, Krick was subsequently to claim the credit for the successful forecast. In truth, his analogue technique has not stood the test of time well, but his drive and enthusiasm ensured that forecasting five days ahead was confronted in 1944 by his more cautious professional colleagues in Britain. This acted as a stimulus to provide the type of advice Eisenhower needed at a time when it might have been easier to equivocate.

After the war Krick returned to Caltech, but left in 1948 to devote his efforts to his consulting firm. It was the first company to offer commercial cloud-seeding (injecting large quantities of tiny crystals into clouds to increase rainfall), another area where US and British meteorologists have not always seen eye to eye. He sold his business to Strategic Weather Services in 1990.

Irving Krick, meteorologist: born 20 December 1906; died Pasadena, California 20 June 1996.