Monday, June 5, 1944, had long been planned for launching D-day, the start of the campaign to liberate Nazi-held Western Europe in World War II. Yet the fine weather leading up to the greatest invasion the world would ever see was deteriorating rapidly. Would it hold long enough for the bombers, the massed armada, and the soldiers to secure the beachheads in Normandy? That was the question, and it was up to Supreme Commander of the Allied Expeditionary Force (SHAEF), General Dwight David Eisenhower, to decide to go or postpone.
Ike would base his decision on the report from his chief meteorologist, James Martin Stagg. Never has so much ridden on a single weather forecast. Stagg had only one chance to get it right. Were he wrong, thousands of men would perish, all important secrecy about when and where the Allies would land would be lost, victory in Europe would be delayed for a year, the Communists might well take control of the continent, and Eisenhower would have been sacked, never to become president, opening the door for General Douglas McArthur who wanted to use nuclear weapons in Korea.
Like many baby boomers whose dads served in WWII, I'd been raised on a diet of military history. From Cornelius Ryan's The Longest Day, I was aware that Ike had put off the invasion for 24 hours. But it wasn't until I read Isaac's Storm by Erik Larson with its fascinating account of the hurricane that devastated Galveston, Texas in 1900 and the hubris that prevented the Weather Bureau from forecasting storm warnings, thanks in part to U.S. Army policy, that I began to wonder just who was Ike's weatherman and how did he arrive at an accurate forecast.
Over a decade, from interviews with American, German, English and Irish meteorologists who prepared the D-day forecast, official records from the British National Archives and the U.S. Army Military History Institute, books, articles, and online postings, I became convinced that this was a great unexplored corner of WWII history.
The 70th anniversary of the landings in Normandy is the time to tell it and The Forecast for D-day and the Weatherman behind Ike's Greatest Gamble (Lyons Press) is the definitive story.
On June 3, 1944, Allied warships had set sail to be in position to bombard German gun emplacements on the bluffs overlooking D-day's beaches. More than 150,000 soldiers were streaming toward their embarkation ports on the English Channel where they'd board transports that would ferry them to beaches code named Omaha, Utah, Gold, Juno and Sword, names that would be indelibly written into history with the blood of 12,000 casualties.
On that night the weather was gentle over Ike's advanced headquarters. Yet Stagg had to stand before him and his senior commanders and deliver an ominous forecast for D-day. Ike sat with his chin in his hand as Stagg delivered his briefing. A string of low pressure cells was advancing across the North Atlantic. Trailing them were cold fronts with thick clouds, high wind and rain. Heavy clouds would prevent Allied air forces from bombing German targets and reinforcements rushing to repel the invaders. High wind would make airborne operations, essential for seizing bridges and roads leading to the beaches, impossible. Heavy seas would prevent landing craft from putting ashore men and material. On the strength of Stagg's forecast, Ike postponed the invasion for 24 hours.
Though a career employee of the British Meteorological Office, Stagg was a very unusual choice to serve as Ike's chief weatherman. A geophysicist at heart, he'd led the British Polar Year expedition to Fort Rae in Canada's Northwest Territories in 1932 and had been knighted for his achievements. Yet his only in-depth forecasting experience had been two years in the Iraqi desert.
However, for two years before being assigned to SHAEF, Stagg had coordinated forecasting for the British Army and the Royal Air Force. And his office was down the hall from Ike's, who had a habit of dropping by on his way to briefings in his map room to ask Stagg about the weather much as he would have chatted about it with his barber back in Abilene, Kansas, where he was raised.
Beneath his friendly smile, Ike was taking steely measure of Stagg. What he found was a consummate scientist whose views were completely untainted by personal ambition or enthusiasm for the mission at hand. That was not the case with the meteorologist who dominated the U.S. Strategic and Tactical Air Force (USSTAF) weather section whose forecasts, along with those from the Met Office and the Royal Navy, Stagg had to meld into a single briefing for Ike.
USSTAF's weather section relied heavily on analogue forecasting. They compared today's weather observations to 40 years of daily weather maps, found the closest match in history, and figured that the weather that followed that day would be much like tomorrow's. The British felt that this was pure bunk.
When Royal Navy and Met Office forecasters predicted stormy weather for the date originally set for D-day, USSTAF meteorologists adamantly disagreed. Circumventing Stagg, they pressed their case with General Carl Spaatz, U.S. Army Air Force commander in England, who attempted to bring their views to Ike's attention.
Had Ike listened to his countrymen's predictions and launched D-day on June 5, it would have failed with catastrophic consequences for the Western Allies and world history. Instead, he held the invasion in abeyance for 24 hours, and as rain and high wind pounded his advanced headquarters on the night of June 4, just as Stagg had predicted, he listened to his chief meteorologist report that the weather would clear, and gave the word to "go" for June 6, 1944.