How one man's forecast changed course of World War II

Read: 2626     16:22     05 June 2019    

One of the most important weather forecasts in world history occurred in early June of 1944, setting the stage for the Allied forces’ fabled amphibious D-Day invasion of Normandy.

With the global community pausing this week to recognize the 75th anniversary of D-Day, the Allied attack on Normandy that changed the course of World War II and altered world history at a tumultuous time near the middle of the 20th century, AccuWeather is taking a look back at the pivotal role a meteorologist played in one of the world's most important military operations.

Thousands of lives and years of preparation were at stake, and on June 4, just hours before the launch of D-Day operations amid an approaching storm, British meteorologist James Stagg urged U.S. General and Supreme Commander of the Allied forces Dwight. D. Eisenhower to make a last-minute delay.

Inspired by Stagg’s history-altering forecast, author John Ross penned the book, "The Forecast for D-Day: And the Weatherman Behind Ike's Greatest Gamble." 

According to Ross, a successful D-Day landing depended on several environmental conditions.

Stagg was a British Royal Air Force Group Captain, and a member of the Allied meteorologists in charge of monitoring the stormy conditions ahead of the Normandy invasion.

Teams of Allied meteorologists, composed of six members, were tasked with finding a suitable time window amid turbulent weather patterns in order to pull off the high-stakes plan.

“There were half a dozen weather ships in the North Atlantic,” Ross said. “There were half a dozen weather reconnaissance flights out of the U.K., out of the north Atlantic every day. They were also reading German weather broadcasts.” 

The Allied forces needed to go in at low tide on the beaches, and the airborne needed enough moonlight to have proper dropping conditions.

In addition, fierce seas would make a beach landing nearly impossible, and the weather conditions at the time seemed to be working against the Allies’ plan.

“Externally, Stagg was a real hard case,” Ross said. “But internally he was just fraught with worry. After he would work on the forecast, he’d take long walks around the estate where Ike’s advance headquarters were located.” 

June 5 was originally selected as the day the Allied forces would launch the invasion. Amid stormy weather conditions, any further delay would have pushed the Allied invasion back another two weeks, buying the enemy valuable time to discover the attack plan.

Only a few invasion dates were possible because of the need for illumination, which moonlight would provide, and for a low tide at dawn to expose underwater German defenses. “They needed to have a period where there was 50% moonlight," Ross told AccuWeather. "The Allies wanted to land at low tide because they knew the beaches where covered in obstacles. Telephone poles buried in the mud with mines on top.” June 5 was the perfect day -- if only the weather would've cooperated.

Hours before the invasion was to take place, Stagg predicted a short break in the weather pattern was coming, but not until the next day. He implored Eisenhower to delay the invasion by 24 hours. Eisenhower was persuaded and moved the attack to June 6. Stagg's forecast would prove invaluable to the success of the invasion. 

According to Ross, many other Allied meteorologists disagreed with Stagg’s forecast, but Eisenhower valued his advice.

“He was certainly worried," Ross said of Stagg. "But he knew the weather, and he knew Ike knew he knew the weather.”

The Axis Powers also monitored the weather patterns of early June 1944, but many left their defenses as they did not anticipate the rough seas or stormy conditions would subside until mid-month and believed the weather elements would prohibit an attack from the opposition.

The departure of their posts and lack of forecast information would help bolster the efforts of the 110,000 Allied forces as they led the charge to liberate France from the control of the Axis Powers on June 6.

In recognition for his service, Stagg was honored with the American legion of merit, and his studies in weather forecasting have been used around the world.




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