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Normandy landings: correct weather forecast saved the day – Defense News
-By Ajey Lele
June 6, 2024 will commemorate the 80th anniversary of the D-Day landings along the coast of Normandy during World War II. The skies above Normandy were once filled with the fury of war. 80 years ago, on this D-Day, Allied troops contributed to the downfall of Adolf Hitler and the liberation of Europe from his tyranny.
June 6, 1944 (D-Day) marked the largest amphibious invasion in the history of warfare. This operation was codenamed Operation Overlord. It required the Allies to use more than 5,000 ships and landing craft to land more than 150,000 troops on five Normandy beaches. It was meticulously planned, with a command team led by American General Dwight D. Eisenhower. This team was formed in December 1943 to devise strategy for naval, air and land operations, necessitating extraordinary cooperation between international armed forces.
The invasion spread into two main phases: an air assault and amphibious landings. Shortly after midnight on June 6, 1945, more than 18,000 Allied paratroopers were dropped into the invasion area to provide tactical support to the infantry divisions on the beaches. Today, the 80th anniversary celebrations have already begun with a mass parachute jump over Normandy on June 2, 2024. During 1945, Allied air forces flew more than 14,000 sorties in support of the landings.
The naval component of ‘Operation Overlord’ was known as ‘Operation Neptune’. Nearly 7,000 warships, including battleships, destroyers, minesweepers, escorts, and assault craft, participated in naval operations. These naval forces were responsible for escorting and landing more than 132,000 ground troops on the beaches. They also conducted bombardments of German coastal defenses before and during the landings, providing crucial artillery support to the invading troops.
One of the least known and rarely discussed aspects of these operations is the importance of accurate weather forecasting for their success. It is often cited that one of the most important weather forecasts in the history of warfare was that of D-Day.
For the Allied invasion to be successful, there was a need for good lighting conditions at night, so the best option could have been a night with a bright, cloudless full moon and calm sea conditions (light winds). During June 1944, the full moon and low tide coincided on the 5th, 6th and 7th of June. This means there was only a three-day window with the necessary astronomical conditions. The proposal for the invasion of Nazi-occupied France was to mount an attack on June 5, 1944.
Until the morning of June 4th the weather remained calm, accompanied by a gentle breeze. However, the situation quickly changed as a series of low pressure systems began to emerge in the North Atlantic, moving towards the English Channel. Leading the meteorological efforts was Group Captain James Stagg, Eisenhower’s chief meteorologist. In 1945, there were no satellites, radars, or computer models for weather forecasting. Instead, weather forecasts were based on pressure information gathered from instruments such as barometers, along with other observational equipment. Long-range forecasting was virtually impossible and military meteorologists could only predict the weather a day or two in advance.
Eisenhower selected June 5 as D-Day; however, Group Captain Stagg was not in favor of launching operations that day, best in this assessment of the weather. The massive landings in Normandy required ideal weather conditions. Strong winds and rough seas could have capsized the landing craft and disrupted the amphibious assaults. Furthermore, rainy weather could have paralyzed army movement and thick cloud cover could have obscured necessary air support.
A collaborative effort between meteorologists from the Royal Navy, the British Meteorological Office and the US Strategic and Tactical Air Force was crucial in the task of weather forecasting. Weather information was transmitted from multiple sources, including weather stations in Canada, Greenland, the Republic of Ireland and Iceland. Additionally, meteorological ships and flights were deployed to collect relevant data.
A specific weather station in Ireland played a key role in detecting a crucial lull in storms. This information, combined with the observations of Group Captain Stagg and his team, led them to believe that conditions would permit an invasion on June 6th. However, on the afternoon of June 4, as the weather began to deteriorate as the first storm approached, Stagg noticed a significant increase in barometric pressure. This observation came from a single report received from a ship stationed six hundred miles west of Ireland, indicating a continued increase in pressure. This led Stagg to conclude that there might be a change in the weather on June 6, forcing his commanders to postpone the operation for 24 hours.
This unique prediction was hailed as a watershed in world history. If it had been incorrect, the consequences could have been catastrophic, resulting in the loss of thousands of lives and enormous amounts of equipment. It is important to note that the weather on June 6 was not entirely clear, but there was a crucial period of relatively clear skies and decreasing winds, allowing air and sea operations.
The crux of the forecast was the prediction of a favorable window for airborne operations. Overall, the weather on the morning of June 6, 1944, was considered satisfactory for the invasion. This accurate prediction ensured that the year-long efforts of the Allied forces were not in vain.
The author is Deputy General Director, MP-IDSA, New Delhi.
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