The invasion of Europe on June 6, 1944 was the greatest military operation in history. If the weather was unfavorable for Operation Overlord, it would have postponed the invasion for two weeks until tides were suitable for landing.  Weatherwise Magazine reported that in 1944, there were no meteorological observations or the use of computer models. Years ago, predicting the weather over the English Channel was challenging.  Weathermen depended on secretive ship and plane reports and from spies on the European mainland.  These observations were coded, forwarded to England and tediously plotted to maps by hand. Numerous groups extrapolated the data including: a civilian group in Dunstable, England, The British Meteorological Service, U.S forecasters called “Widewing” and the British Navy. On May 31, 1944, a series of low pressure systems set-up from Nova Scotia to Scotland that had characteristics of a possible hurricane. An Azores high could deflect the storms however too much cloud cover and the advance bombers would be useless; too much wind and the landing craft couldn’t function.  Dr. J.M. Stagg coordinated all forecasts to produce a consensus forecast that met the approval of General Eisenhower who attended the daily weather briefings.  Stagg was not optimistic about the invasion, offering a postponement to the supreme commander on June 4. On June 5, he advised that the weather would be tolerable for the landing on June 6th.