How did I miss this one….
Back then the Met Office was a part of the Air Ministry and from there evolved to what we have today. Most Met Staff had a military rank, we still do when serving in certain areas. There has been some mammoth advances made in weather forecasting since then. Details in forecasts were much less specific and things like intensity of rainfall, heaviness of snow that sort of thing wasn’t possible. It’s maybe a bit unfair to try and compare both times.
One or two inaccuracies in the Retrocop’s comments. There wasn’t big network of upper air soundings just a few but they were important; knowledge of the upper level of the troposphere was very much in it’s infancy. We did have a very extensive observations network and ships around the sea areas, we also had surface observations from most of the allied shipping military or civil. The big advantage the allies and Stagg in particular had was access to every single German weather observation through Bletchley Park after we broke the Enigma code system. Weather information was critical to the allies.
Even the weather forecasting was a battle with other groups involved the US tactical Air Force forecasters and the Navy but Stagg and the Met Office won in the end, science won the day.
Stagg created his analysis from predominantly surface observations, the last chart he produced at 1200GMT the day he gave the briefing is now a national treasure and sits in our library, I’ve seen it and its still quite inspiring to me even after nearly 30 years doing the job. He would have used plotted observations or surface pressure to create the isobar field and highlight the highs and lows. He used pressure tendancies (Changes over a three hour period), wind speeds and direction, temperatures and dew points, cloud, weather types and visibilities to locate fronts and troughs. This would allow him to use his knowledge and experience to build an synoptic analysis and in turn a forecast analysis by following the movements of the pressure systems relative to each other. It was these skills I learned nearly 30 years ago…. With the same information he had anyone with similar knowledge could create the same analysis and forecast.
On single set of observations for ships to the west and a lighthouse in Ireland reported rising pressure and an easing in the stormy conditions allowing Stagg to predict the magic window with an amazing level of precision, just enough to get the landings underway and bridgeheads built but they also knew the risks as the storm pushed through witnessed by the destruction of one of the Mulberry Harbours in the following days. The D Day forecast was sublimely accurate and that level of accuracy can not be understated it was a touch of genuis that can only be done by humans, properly trained forecasters.
Today the Met Office is still part of government which is both a good thing and bad in many cases. The RAF, Army and to a lesser extent the Navy still rely on us to do their jobs safely and assist in tactical decisions to this day.
Nowadays, satellites and automated sensors provide much of that observation, the global upper air network is a fraction of the size it was ten years ago because the modelling is so much better. Our forecasters have to have the knowledge to interpret the model output and from that create forecasts on a global scale and in a large number of market sectors. Our supercomputer can do over 1000 Trillion calculations per second (FlOPS) but needs to be quicker. Like in 1944 our forecasts and service saves lives and money a recent independent report suggested we saved the uk economy around £260million per year. The UKs Met Office is still reagrded as the best Met service anywhere on the planet, it’s people like Stagg and his successors who we can thank for putting us in this position.