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We owe them so much, an incredible shot of Infantrymen in a Landing Craft Assault (LCA) going ashore from H.M.C.S. Prince Henry off the Normandy beachhead, France on June 6, 1944. The Photographer was Dennis Sullivan. 

The 75th Anniversary of the Allied invasion of the Normandy Coast

Lest We Forget...

Thursday is the 75th Anniversary of one of the most important dates of the 20th Century, D- Day, June 6, 1944. The invasion of the Allied Forces at Normandy would be the start of the liberation of mainland Europe and the eventual end of World War II. On this day, I want to express my gratitude to all those brave men and women who paid and continue to pay the ultimate sacrifice so that we can enjoy our freedom. Without them, none of this is possible.

The forecast for the English Channel during D-Day, the Normandy invasion in June 1944, would become one of the most important ever delivered throughout history. Nearly 160,000 Allied Troops, including 14,000 Canadians, would be relying on its accuracy. The entire free world had an interest in this forecast being as precise as possible. Strong winds, rough seas or dense fog and cloud cover would have been disastrous for the invading troops.

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A hand drawn map showing the weather systems impacting the North Atlantic just prior to the D-Day invasion in June 1944. The Allied Forces used superior forecasting techniques and observations to better the Germans and find a narrow window of opportunity for the June 6 invasion. The map above shows a small break in weather systems over the English Channel, while another strong ocean storm waits over the Atlantic Ocean south of Greenland.

Supreme Commander of the NATO forces, General Dwight D. Eisenhower needed nearly ideal weather conditions to launch the invasion. The perfect day would have a full moon, low tides, clear skies, light winds and low seas. Two such periods matched the low tide scenario, but only one had the light of a full moon, June 5, 6 or 7, 1944.

The prognostication fell on the backs of a team of forecasters from the UK and the USA, sprinkled with a few other Allied scientists. The forecast team was lead by British meteorologist James Martin Stagg. Stagg lead three teams of forecasters who would argue back and forth for days testing each others abilities and theories to come up with the right day for the invasion of the Normandy Coast. The safety of the troops and the effectiveness of an entire campaign lay at stake.

Weather forecasts were considered a matter of national security. For this reason neither side issued public weather forecasts during the war. However, because the Allies had cracked the German codes, the D-Day forecasters had access to German meteorological observations as well as observations from Allied observers and reconnaissance flights. 

It was up to the forecasters to give the best idea as to which 24-hour period would be best to launch the invasion. Early forecasts predicted stormy weather for the time frame in question. Eisenhower wanted a Beaufort Scale wind of 4 or less to give the go ahead. Force 4 winds are 13-18mph with 3.5 to 5 foot seas. Anything greater than that would swamp the landing craft and sink vital equipment. The challenges were many, so the hope was to give the landing forces the best chance possible. Any type of cloud cover would hinder air support and limit paratroopers.

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Destroyed military equipment lies in the surf at Juneau Beach on D-Day, June 6, 1944

The massive Allied Force of over 160,000 troops, including 6500 ships and hundreds of aircraft, began staging as early as June 3 in what had been up to that point a decent stretch of weather. That was about to change, as a series of low pressure systems and fronts traveling across the North Atlantic was about to bring very poor weather. By June 4th, the weather had turned, with strong winds, low visibility, high surf and heavy rain. Stagg approached Eisenhower with the advice to delay the invasion, this despite the US forecasters insisting the weather was acceptable for an assault. Eisenhower decided to wait 24 hours. Thousands of troops remained in place on ships in rough seas for an additional day. The armada was deployed instead in the early hours of June 5 for the 17-hour trip across the English Channel and a June 6 sunrise assault. Despite the 24 hour wait, the weather was less than ideal with 5 foot seas, but a vast improvement over the 6 or 8 foot seas and poor visibility during the previous 24 hours. To show how devastating it could have been, even the lower wave action swamped several of the landing craft and left at least 2 dozen tanks submerged at Omaha Beach alone. This would lead to little ground support for Infantry, and massive casualties to the US forces.

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Canadian Troops guard a group of German prisoners on Juno Beach on June 6 1944.

The Germans were caught by surprise, as their forecasters had told German command the bad weather would last well into June and thus prevent any invasion. Many German soldiers and Generals were granted leave due to the perceived bad weather.

The rest as they say is history, with the invasion succeeding, but unfortunately at a terrible cost. As many as 10,000 casualties (dead & injured) occurred, including 1074 Canadians (359 Canadian deaths). Eleven months later Germany would surrender. You can never downplay the importance of D-Day in bringing World War II to an end. One can only imagine how much worse the invasion would have gone had Eisenhower decided to leave on the 4th while a cold front whipped up heavy rain and strong winds along with very high seas and low visibility. Stagg’s forecast to travel in the relative good weather between low pressure systems on June 5, 1944 no doubt lead to the success of the invasion, as well as saving countless lives.

By the time the initial battle came to an end, the sun was shining down along the Normandy coastline. 

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