Stagg

Relying on readings Sweeney took at Blacksod Point, the Allies’ chief meteorologist, a Scot named James Martin Stagg, finally told Allied commanders that the weather would be unfavorable on June 5.

For Stagg, the data from Blacksod confirmed his forecast that a low pressure system would move in from the Atlantic, bringing high winds and thick clouds to the Normandy coast on the night of June 4 and into June 5.

That helped Stagg forecast another change in the weather, and later that day, he told Eisenhower that he expected the winds to die down and the clouds to abate in time for a landing on June 6.

“Well, Stagg, we’re putting it back on again,” Eisenhower told his chief forecaster, according to Stagg’s book, “Forecast for Overlord,” Ross said.

The weather report from Belmullet was enough for the chief meteorological officer, Group Captain James Stagg, to advise that the invasion be postponed by 24 hours.