INDIANAPOLIS (WISH)– The D-Day invasion was originally planned for the morning of June 5, 1944, but a large storm over Scotland created rough weather in the English Channel resulting in a 24-hour delay. 

There were no computer models predicting the fluids of the atmosphere, no satellites showing cloud patterns and radar was in its infancy. All meteorologists had to rely on were surface observations. 

The three-day window in early June was picked because of astronomical conditions. Troops needed moonlight in order to see and a low tide early in the morning to show underwater German defenses. 

Meteorologists from the British Royal Navy, British Meteorological Office and the US Strategic and Tactical Air Force analyzed surface observations and worked together creating the forecast. Captain James Stagg with the Royal Air Force suggested to President Eisenhower the weather would be too rough on the morning of June 5, 1944 and to delay the mission which was called “Operation Overlord” by 24 hours. 

The Allied forces had a much better network of surface observations in Europe than the Germans. The German meteorologists predicted that the weather would continue to be stormy through the middle of June and pulled many of its forces off posts along the coast and started to participate in war games. 

Captain Stagg predicted there would be a break in the strong winds and high seas on June 6, 1944 and with that knowledge Eisenhower gave the green light for the invasion. Winds and waves at first were rough sending some paratroopers and mortars miles off course. The weather eventually cleared by noon. This gave the allies the element of surprise since the Germans assumed the weather wouldn’t clear. 

The next available time for low tide would’ve been two weeks later in the middle of June. During that time another storm moved through the English Channel and produced what was described as “the worst channel weather in the last 40 years.”