The Weather over the Target

Thanks Peter

Thank you for your informative contribution Peter, it’s always good to have the experience of one who’s dunnit!!
Regards
Max

Bombing Weather

To answer Blue Robin’s questions:
Pigeons – almost never.
Radio – quite a lot. Decrypting German and Italian Met Reports and Forecasts was a significant part of the work at Bletchley. Indeed, it was decrypting these messages (in an Enigma code Bletchley could read) and comparing the same messages re-broadcast by the Germans in the U-Boat code which was one of the methods whereby the U-Boat code was finally ‘cracked’.
Spies – unlikely.
Resistance – possible, but their reports were irregular and the quality highly variable!

To over-simplify the process, forecasting consists of taking a snap-shot of the weather (the Actuals, Reports, etc). This is the Analysis. Then do the same thing 6, 12, or 24 hrs later. From these two charts it is possible to work out how fast, say, a Low is moving, and in which direction. Take that movement and/or development into the future time and you have a Forecast. The same system is in use today – but now done by computer. In WW2 it was all done on paper charts with pencil and rubber (LOTS of rubber!).
This was fine in forecasting for a bombing raid over Germany if the Low was moving from west to east. The weather that had occurred in the UK would, in X or Y hours, be over Germany. However, if the weather system was moving N/S, or S/N, in what the Met Men call a “data-sparse” area (German occupied Europe) then the forecasters had little idea of what had actually occurred, let alone forecast what it might do. This, as has been pointed out, sometimes resulted in serious errors (particularly in the route and bombing height winds), with consequent casualties. Forecasting in WW2 was – again, as has been said – an Art Form. Today it is more of a Science (but yet to reach 100% accuracy!!!!)
Routine daily Atlantic Met Recce flights were NEVER routed over enemy territory. Special Met Flights – in connection with a particular Operation – WERE routed over enemy territory.
What bombing cloud conditions were required varied (and I am not an expert). At the beginning of WW2 the RAF could not, at night, navigate to the target with any degree of accuracy (read the Butt Report!). Later in the war with radio aids (H2S, OBOE, etc) it would be possible to bomb, with some accuracy, through 8/8ths undercast.
It was (and is!) a big problem. Some of the WW2 RAF raid “errors” are still being researched today.
HTH
Resmoroh (ex-Met Office)

No 1409 Met Flight sent Mosquitoes on weather flights over the enemy territory to get data back not only for the RAF but the American daylight bombing raids. Based at Wyton at the end of the war they continued at Lyneham under Transport Command.

Weather reports

It was a bit more of an art form, if not yet quite the precise (?) science that it was to develop into. There were squadrons whose function was to do met. flights over Europe to bring back data: the forecast of what was likely to happen was critical and could lead to raids being scrubbed or not. Wind strengths and directions were also very important – flying into a headwind could have a significant effect on fuel consumption so this would have to be allowed for in the pre-sortie calculations and the actual consumption carefully monitored by the flight engineer whilst on the sortie. Met. sometimes got it very wrong which on occasions contributed to heavy losses amongst aircrew. Wind velocity and direction readings were also taken whilst on a raid and logged in the navigator’s log…certain aircraft sent this data back to base.
The following extract is from the BBC’s People’s War site:

The training consisted of learning to do an observation, including a night observation, learning the reporting codes and how to plot charts and the other material that you would have to learn about. The met. Traffic system was by tele printer.
The station construction was from air stations which all belonged to their own group which in turn reported all their data to the met. Headquarters so reporting was in three things.
So the out stations reported to the group HQ’s — this is where the actual airforce operational work was (where the aircraft where) and the group was a collection of all the out stations and in turn at the back of all this was the met office HQ at Dunstable.

We were frozen in the land registry where we attended most lecturers and we were ‘cooked’ in our living quarters – the block of flats which has been bombed and the windows having been almost bricked up.

Then having finished with the actual training school in London we were then posted to an RAF station.
There we were under the supervision of the Duty Assistant because that is what we were going to be.
By the time we had finished our training — probably two or three months — we were then sent to an actual station and had to take on a shift on our own.

A shift meant you worked round the clock in turn.
The group where I was sent was an Operational Training Group with Units (OTU) It’s main function was the continued training of aircrew after the completion of Initial Flying Training and being fully operational. The aircraft were mostly twin engine Wellingtons, there was an insufficient number of 4 engine bomber aircraft available for anything except operations.

In our Training School period we had learned the plotting codes for charts, plotting of Radiosondes (these were appliances used by various stations and they recorded Upper Winds and Temperatures).
The winds were listed on a special form and the Temperatures plotted on a somewhat complicated graph. There was also special met. Flights the one over the North sea being of paramount importance as we were part of bomber command.
We were known as met. Assistant.

Every hour we had to do an observation which was coded and sent on the teleprinter network to the group HQ and subsequently to the HQ of the met. Office at Dunstable.

The cloud formation was divided into low, medium and high clouds. We had to assess wind speed and direction, check temperature and barometric pressure.
The coding we had to learnt to describe present weather.
Weather in the past hour and any special phenomenon — this was coded into groups of 5 figures and from a station you waited to be rung by your group HQ and then you sent it.
In turn the group HQ having collected all the observations of the group would transmit it to Eta — this was the HQ of met material (in fact it’s head office).

Eta would then collect all the observations from the group HQ and re broadcast it by about 8 minutes past the hour. The groups had a certain order of re broadcasting and from this the met assistant plotted the charts.

We should have worked three eight hour shifts but we didn’t — the late shift was the shortest and the night shift was longest. Whilst on the night shift we would have the basic rations of two slices of bread and margarine and tea. The night duty assistant collected these before going on duty. We all became experts in making toast on whatever lent itself to this task.

I did this for 4 and a quarter years. 1941 — beginning of 1946

In addition to having to do the observations which were transmitted to group and then to Eta, charts were plotted every three hours. The four main charts were plotted at 0001, 0600, 1200 and 1800 gmt.
All relevant material had to be plotted and in addition reports from radio sondes and met. Flights.

I still remember the code names of the flights.
Rhombus was the one over the North Sea.
Bismuth was the one from Northern Ireland.
Epicure was later done by the Americans who also had to report into our group.

Rhombus was particularly useful to bomber group as it was used as a forecast for that nights bombing raids.

The met flights and radiosondes were plotted on the main charts at the four full synoptic hours.
The radiosondes were called PRAWTS (Pilot Radio Ascent for Wind and Temperature)
There was also a PRAT from Cornwall (For Temperature only)

As ours was an operational training group various flights were undertaken over the British Isles and at the end of an air craft course. One sorti over enemy territory would be required — this would also serve to divert enemy aircraft fire from the bombing target of that night.
The navigators normally collected the forecasts which were compiled mostly by the group HQ.

Weather was always happening so there was always something to do.

We had to watch out all so for sudden deterioration or improvement and send these via the group HQ to Eta.
Hope this helps
Max Williams