Today Should Have Been The 70 Year Anniversary Of D-Day

June 5th, 1944! Today should be 70th anniversary of the historic battle that helped the United States and its allies secure victory in Europe during the Second World War! But did you know that mother nature herself was the reason for a delay in the historic invasion?

When planning for the assault, weather forecasters did not have the luxury of computer forecast models like we do today. Meteorologists relied on data from ships at sea to monitor observations, reconnaissance flights, weather balloons and visual observations. Through these methods, meteorologists were able to successfully give the go ahead for the June 6th invasion date. However, June 6th wasn’t the original day officials had marked for the invasion. Originally, the invasion was set to take place June 5th, 1944, but due to a report handed directly to General Eisenhower from his meteorological adviser the landing was rescheduled for the next day. That report included the summary of several factors that needed to come together to make for ideal conditions for the troops coming ashore..

1) The landing needed to be around the time of a full moon to help illuminate as much of the beach as possible.

2) It had to be during a period of high tide so the vehicles could make it inland as far as possible.

3) Calm weather conditions were ABSOLUTELY needed! That meant a clear sky and calm winds!

Thanks to a re-analysis by the European Centre for Medium Range Weather Forecasts (ECMWF) and data From the US National Weather Service we can see the conditions graphically as they were in early June 1944. Meteorologists were able to successfully predict an occluding area of low pressure and frontal system bringing clouds and high winds to Western Europe and more importantly the English Channel on June 5th, 1944. This definitely didn’t sit well with those planning the invasion.

June 5th Forecast

The decision was made to postpone the invasion until the early morning hours of June 6th, and though the conditions weren’t ideal, they were good enough to launch the assault. The alternative would have been to wait until the next month when The moon would once again be full. Here is the forecast of the cloud cover and winds 24 hours later during the early morning hours of June 6th, 1944.

June 6th Forecast

And here was the actual analysis of that day that verified the forecasters accuracy and legitmized the difficult decision to postpone the invasion by 24 hours.

JUne 6th Analysis

With that, the invasion began. Here are pictures of that day confirming the partly cloudy skies that were forecasted.



I couldn’t write a post like this without acknowledging BOTH of my grandfathers and their service! Both of them were pilots in the Europe theatre during WWII.

Capt. Donald Block, WWII B-26 Marauder Pilot, Europe

Capt. William Adams, WWII B-24 Liberator Pilot, Europe

And thanks to ALL our troops who serve!


Here is the ECMWF report on the Normandy invasion

Here is a link to the US Naval Historical Research Center where the above pictures are from.



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