Part 17 (2/2)
Other parts of the military establishment listened in-to ensure that our top-level D-Day forecasts did not conflict with those regularly given to lower-level naval, air and army formations.
On that first day, Stagg introduced me, saying, ”You'll all be pleased to hear I have a new a.s.sistant, Henry Meadows, a bright Cambridge natural sciences graduate who I hope will pitch in from time to time. He has worked with me at Kew and trained as a Met observer under Mr Douglas.”
I said h.e.l.lo to Douglas, who I think was pleased to hear from me, and reacquainted myself with Krick, hoping he wouldn't mention that we had played poker and got drunk together, which I doubted Stagg would approve of.
But he didn't, just drawling, ”Well I'll be d.a.m.ned, Henry. Welcome aboard.”
The first job of the conference was to agree on a map of current conditions, and I would soon discover that not everyone always turned up with the same map, let alone the same forecast. It often took about half an hour to sort all this out.
Once actual forecasting got underway, Petterssen at Dunstable was first to speak, his strong Norwegian accent interrupted by the occasional clicks and static of the telephone wires. It took me a while to become familiar with all the codes they were using to describe areas of high and low pressure...H1, H2, H3...L1, L2, L3...
It was standard that H stood for a high pressure area, L for a low, but the numbers to which they were attached were altered from time to time as a further security precaution, should the enemy be listening. Given the transitory nature of weather, our counterparts at the Zentral Wetterdienstgruppe were going to be hard pressed to interpret any intelligence they might receive. I wondered whether Sir Peter had been able to get anything more out of Heinz Wirbel, the scientist who had bailed out of the Junkers.
”As I forecast last time,” began Petterssen, ”L1 has moved east-north-eastwards, bringing further deterioration from the west in its wake as the week progresses. There will be increase in cloud and freshening west-north-westerly wind through the week, switching to west-south-west up to force four or five on Wednesday, as an interval, deterioration continuing into Sat.u.r.day, when there is risk of rain...”
”Patches of low, low, low...,” interrupted an English voice.
”Lowish cloud along s-south-west coasts on Tuesday morning, some of these, er, at a base of one thousand feet, mixing with, with fog patches in the western Channel.” It was Douglas. ”Mainly fair to Wednesday, then G-G-G.o.d knows.”
Someone else on the line grunted. I heard Stagg sigh beside me. The echo repeated in the handset against my ear.
”I can't go along with this,” said an American, unmistakably Krick. ”You're far too gloomy, Petterssen. I see quiet, fair weather in all areas, especially from Wednesday. Considerable fine intervals, especially in eastern areas. Good visibility except for those local morning fog patches Douglas mentioned. They'll burn off quick.”
”What about that low?” countered Petterssen. ”Surely you can see that low coming? High pressure in the north-east Atlantic is bound to force it through.”
”That cyclonic cell, not very considerable in my view, will anyway collapse within two days, allowing the warm period I mentioned,” said Krick. ”There are many a.n.a.logues for a settled period like this, in May 1929, for instance, and the following year. This is how it will play.”
He spoke with great confidence, with bravado, in fact. That was the thing about Krick. He did not have the intellectual power or ethical rigour of the others who sat, at least figuratively speaking, round that table, but he had something none of the rest of us had. Conversational force, and the ability to make a narrative of a scientific forecast. The latter, especially, is a really important quality in a forecaster.
But if the story's wrong then the whole team is in the soup. And there were other voices round that table that were often convinced Krick's predictions were way off beam. In their own minds, these speakers were actually just as confident as Krick, even if they didn't sound so.
”Um, not n-n-n-necessarily,” said Douglas. ”We had a development like this in May 1931. Pressure over Europe was a little lower than now, and not so high in the north-east Atlantic. But the upshot was a period of north to-north-east winds which continued for ten to twelve days; they r-r-r-reached gale force at times in the eastern Channel.”
There was a pause in which the telephone wires clicked and whirred as if, somewhere in the depths of the exchange, a mechanism was running down.
”G.o.d almighty,” said Stagg. ”We'll come back to this. Navy?”
”We lean towards Petterssen-Dunstable on the general forecast,” said a good-natured voice with a New Zealand accent. This was Lieutenant Hogben. ”Fine weather but risk of rain on Sat.u.r.day. On the maritime side of things, and I remind you this is an amphibious operation, we expect no appreciable swell. Waves less than two feet at first, probably increasing to four feet in the eastern Channel and six feet in the western Channel.”
”Right,” said Stagg. ”Well now, either Dunstable or Widewing will have to relax its view. It seems to me-and you must remember that my job is to present a single, confident reliable forecast to General Eisenhower-that the divergence rests on what happens at the end of the week. We all know how, by its very nature, the structure and processes of weather can produce interminable discussion and still spring-”
There was an unearthly moan throughout the whole complex as the generators went down and the lights were extinguished.
”Potas.h.!.+” shouted Stagg.
”What's that?” said Yates's American voice in the darkness.
”I say potash so as not to swear,” said Stagg. ”It's a bombing raid,” he explained to me. ”We always just shut off the electricity because if they hit SHAEF-well, it's all over then.”
The phones themselves were clearly on a different circuit from the mains, and this enabled us to keep talking. I heard some distant explosions, but could not estimate how near the bombs were falling or of what magnitude they were.
”Some way off,” said Yates, as if reading my thoughts.
The lights came back on, but the discussion had stalled. The experts still could not agree. Stagg became quite angry, as he had to deliver a five-day forecast to Elsenhower the following morning.
Douglas disparaged the whole idea of five-day forecasts. ”You can have as m-m-many conferences as you like,” he said. ”They will make no difference: it is just not p-possible to make regular forecasts five or six days ahead that can have any real v-v-value for military operations or any other p-p-purpose.”
”Scientifically speaking, there are no reasons why long-range forecasting should not be possible,” said Petterssen calmly.
”Of course it's possible!” bl.u.s.tered Krick. ”Precise long-range weather forecasting requires day-by-day prediction for years ahead, and that is what my a.n.a.logue sequence method provides. Look at the chart and the comparison of previous weather sequences from 1930 I sent through.”
”Pure guesswork from t-t-two days out,” mumbled Douglas.
”How dare you!” exploded Krick through the earpiece. ”I've been through half a century of northern hemisphere weather maps. Because of that, I am able to give a mathematically reliable five-day forecast.”
”There is only one man in Britain I know able to do weather prediction by d-d-direct attack with mathematics,” said Douglas, ”and even he would admit it is a p-p-process very liable to error. His name is Wallace Ryman.”
A chill went through me. I was wrong that everyone in the meteorological community knew what had happened. ”He's dead,” I said immediately, hearing my own voice in my ear a second later. ”Ryman is dead. He died in an accident in Scotland. I was working with him there.”
”Oh dear,” said Douglas. ”What a p-p-pity. I remember going to Norway with him to see your p-p-people in Bergen, Sverre.”
”Yes. I heard about him from Bjerknes, my tutor,” Petterssen said. ”I'm afraid to say he was regarded as a strange sort of character. He brought a gun with him, to measure wind shear. Many considered the gun a toy and the man himself an overgrown Boy Scout. It is a shame, though, that he abandoned meteorology before his numerical weather process could be put into practice.”
I thought of Ryman with his gun in the field. Was he not the great man I'd thought? ”Well,” I bristled, feeling the need to stick up for him, ”until his death he devoted himself to the application of mathematics to peace studies. I think many of his meteorological ideas are still valid, nonetheless.”
”Devoted himself to what? what?” said Krick, incredulous.
”Peace studies. He applied mathematics to the relations.h.i.+ps between opposing forces to see how war might have been avoided.”
”Gentlemen, can we please make a forecast?” said Stagg. ”On exactly what issues are we divergent?”
There was a babble of voices from all sides.
”My past a.n.a.logues are right,” said Krick. ”The whole US weather service is run on this basis.”
”It must be informed by theory,” said Petterssen. ”Otherwise it is worthless.”
”You must look at the prevailing pattern before you consider other factors,” said Douglas.
I felt the need to speak again, but it was as if the voice coming through me was not my own. ”Future weather is a judgement of probabilities based on physical principles which are reducible to mathematical formulae. There is one I know which relates temperature and wind speed to produce an index of turbulence. The Ryman number. You may have heard of it. Well, I could try and find its values for the Channel weather in the relevant period.”
Silence ensued. Of course, I now feel it was a mistake to have brought up the number at the first conference, but I suppose I was trying to prove myself.
”Very good, Meadows,” said Stagg eventually, like a schoolmaster congratulating a pupil. I perceived a slightly embarra.s.sed tone in his voice. ”Do so, though in my experience weather is less reducible to numerical process than Ryman and, clearly now you, believe.”
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