Weather forecasts compiled for Dwight D. Eisenhower's invasion
of Normandy on D-Day 50 years ago are among the meteorological
mementos kept by Air Weather Service at Scott Air Force Base
Eisenhower knew the importance of those forecasts, says Col.
Gene J. Pfeffer, vice commander of Air Weather Service. Bad
weather common to the English Channel in the spring could easily
have botched the entire invasion on June 6, 1944.
Success would require an astonishing combination. As Eisenhower
himself put it:
"We wanted to cross the Channel with our convoys at night so
that darkness would conceal the strength and direction of our
several attacks. We wanted a moon for our airborne assaults. We
needed approximately 40 minutes of daylight preceding the ground
assault to complete our bombing and preparatory bombardment. We
had to attack on a relatively low tide because of beach obstacles
which had to be removed while uncovered."
Troops also would need seas calm enough for landing in the surf
and winds could not be strong enough to prevent parachute drops.
After the initial assault, the Allies would require a stretch of
reasonably good weather for landing reinforcements.
"That's a tall order," Pfeffer remarked with understatement.
Pfeffer was not yet two years old when the Allied invasion of
Normandy took place. But in 30 years as a weatherman, he studied
D-Day in depth.
"There were no weather satellites, no weather radars, no
sophisticated computer forecasting techniques, and no large network
of stations providing upper air data critical to longer range
forecasting," Pfeffer wrote in a research paper while attending the
Air War College. "Despite these limitations, the Allied weather
team was imminently successful."
An American team led by Col. Donald N. Yates worked with
British weather experts. Eisenhower had them start making five-day
forecasts two months in advance. "He wanted to know how good they
were," Pfeffer said.
The British Admiralty team, a team of forecasters from the
British Medical Office and the American Army Air Corps team each
thought themselves the best.
"They had even had some difficulty agreeing on what the current
status of the weather was," Pfeffer said. "Needless to say there
were some personality conflicts."
Eisenhower would need to know four days before D-Day if weather
would halt the invasion, according to Pfeffer. Good weather the
day of the invasion would be of little use if bad weather in the
preceding days prevented force buildup and re-supply.
The same forecasters also had to furnish weather predictions
for bombing missions and other operations in the two months before
D-Day, aimed at disrupting German rail lines and bridges.
In the days before the invasion, they conducted a weather
conference at 3 a.m. daily, in preparation for Eisenhower's daily
staff meeting at 4:30 a.m.
On difficult days this conference sometimes "took on
characteristics of a knock-down, drag-out fight among strongly
opinioned professionals," Pfeffer wrote in his War College paper.
"Each was convinced that his vision of the future weather in the
Channel was correct, and each knew the incalculable cost of bad
advice to the Supreme Commander. …