Maureen Flavin Sweeney; her weather report helped guide timing of D-Day
Before dawn on June 3, 1944, a postal clerk in Ireland’s County Mayo checked her weather gauges. A storm was coming fast. The barometer readings were dropping. The wind, pouring off a low-pressure zone in the mid-Atlantic, was slicing through the drizzle in the village of Blacksod.
She double-checked the observations. They then were passed along until finally they reached Britain’s Met Office, which since 1939 had used the Blacksod post office as one of its weather stations. Blacksod carried particular importance. Its position on Ireland’s northwestern coast was often an early warning of Atlantic weather systems headed for Britain.
The data collected that morning was the most significant yet. About 7,000 ships and landing craft, 11,000 aircraft, and more than 130,000 Allied troops were amassed for Operation Overlord, the invasion into Nazi-occupied France. The only missing puzzle piece was the weather forecast for the English Channel to decide if June 5 would be DDay.
The storm observations from County Mayo were the first indications of trouble ahead. The invasion was postponed until June 6. And the postal worker — 21year-old Maureen Flavin — became part of World War II lore as a linchpin in the weather team whose work persuaded commanders to hold off for 24 hours the air-and-sea assault that helped change the course the war.
“They could arrange everything, but they couldn’t prearrange the weather. . . . We eventually had the final say,” Maureen Flavin Sweeney, who died Dec. 17 at 100, later recalled.
Ms. Sweeney was one of the many civilian women involved in nearly every facet of the war effort. Few, however, had moments so directly connected to major decisions as Ms. Sweeney on that gloomy June morning.
For a tense few hours, her weather readings and observations were given top priority as they moved up the chain of command to Group Captain James Martin Stagg, a Met Office meteorologist attached to the Royal Air Force. Stagg also was the chief weather adviser for General Dwight D Eisenhower, who was in charge of D-Day operations.
The weather forecast was pieced together based on barometric data, wind patterns, cloud formations, and sometimes just accumulated local knowledge of the skies and seas.
“A bad forecast would jeopardize the entire operation,” wrote author John Ross in “The Forecast for D-Day” (2014). “If [Eisenhower] gave the word to ‘go,’ and the weather turned sour, the lives of thousands of men and massive amounts of equipment would be lost.”
As Stagg reviewed the incoming information — from Ms. Sweeney and other weather watchers — nothing looked promising. At 11 a.m. in County Mayo, the phone rang at the Blacksod post office. “A lady with a distinct English accent requested me to ‘Please check. Please repeat,’” Ms. Sweeny recounted in an interview with Ireland’s RTÉ.
The conditions effectively nixed the core of the D-Day operations: the massive amphibious landing on Normandy beaches and airdrops of paratroopers behind the German lines.
The weather cleared sufficiently by June 6, 1944, for the invasion to begin.
For more than a decade, Ms. Sweeney was unaware of her part in D-Day. As once-secret war information was unsealed, the connections were made between the D-Day postponement and the weather data, including the early reports from Blacksod.