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Weather Predictions

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retrocop | 12:58 Fri 06th Jun 2014 | Weather
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Has any one wondered how accurate weather patterns and predictions were arrived at during the 2nd WW and on D Day in particular?
In those days,despite the hostilities,there were weather ships anchored around the coast.Weather stations in remote places in the UK.The RAF had a meteorological section.Weather balloons recorded patterns constantly.Cloud cover over targets could be predicted,theirs and ours,fairly accurately and a small window of weather "let up" to put the troops ashore in the middle of the worst predicted storms in the Channel for many years.The met boys were certainly more on the ball it seems in those days even without today's computers and satellites.Nowadays the forecasts are full of probably and maybe's.

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Narrow it down to a smallish, specific area (eg the Cotentin peninsula) and a short window of time (say between 7-8 hours from now) ... then the Met Office would be able to give you a very accurate forecast. The trouble is that we expect them to forecast for the whole of the UK for the next 48/72 hours - then deliver that forecast in layman's language in around 60...
13:33 Fri 06th Jun 2014
Pot luck I reckon, just like it is 70 years later.
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I think,considering so many lives depended on the weather, be it in the air,landing beaches or in the cities and towns it was a little more than just pot luck.It would seem a higher degree of accuracy was obtained with less sophisticated equipment in those days.I am not suggesting that lives today don't depend on the weather of course.The fishing industry etc.
Narrow it down to a smallish, specific area (eg the Cotentin peninsula) and a short window of time (say between 7-8 hours from now) ... then the Met Office would be able to give you a very accurate forecast.

The trouble is that we expect them to forecast for the whole of the UK for the next 48/72 hours - then deliver that forecast in layman's language in around 60 seconds.

It's virtually impossible - even before that dratted butterfly starts flapping its wings :)
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A good point sunny-dave.
There was a story recently that the "accurate" forecasting involved in launching D-Day when the Germans didn't expect it (a tiny break in a lengthy storm) was nothing more than pot luck, and that the signs were misread. Things worked out anyway, but there is part of your answer. It was a far more haphazard business, weather forecasting, back then, and sometimes luck does indeed play its part. It's probably the scale of ambition of modern forecasting (and the "Don't worry, there isn't" remark) that makes things look somehow worse, but they aren't really.
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.
It's reigniting and fusing retrocop

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