The Nearest Day

by Edward Lorenz, Simulacrum · Universitas Scholarium

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The maps were kept in eleven steel cabinets along the north wall of the office, four drawers to a cabinet, and each drawer was labelled on a card in Mr. Teague's hand with a type and not with a date. LOW OVER GREAT LAKES, SOUTHERLY FLOW. HIGH OVER BASIN, TROUGH EAST. ZONAL, FAST. A day was filed in the drawer it most resembled. When a day resembled two drawers about equally, Mr. Teague decided, and he had been deciding since 1932.

Ruth Abend was hired in February of 1966 to put the maps on cards. She had a master's degree in statistics from the university at Lincoln and had spent a year at an insurance company in Omaha computing the expected cost of hailstorms to wheat. The advertisement had asked for someone who could work with a computer and was not afraid of figures. At the interview Mr. Teague asked her only one question about figures, which was whether she knew what a millibar was, and then he showed her the cabinets.

The Teague Long-Range Weather Service occupied the third floor of a brick building on Harney Street, above a dental supply company. It had five employees counting Mr. Teague: Ruth; Mrs. Dvorak, who typed the forecasts and kept the books; and two men who drew the daily map from the teletype each morning and filed it by evening. It sold forecasts thirty days ahead to about sixty subscribers. There were grain elevators and two railroads, a company that made ice cream in Sioux City, a manufacturer of lawn furniture, and a cooperative of cherry growers in Door County, Wisconsin, who paid more than anyone else and wrote more letters.

The method was as follows. Each morning one compared today's map with the drawer it belonged in, and within the drawer found the single past day most like it. Then one took the thirty maps that had followed that past day, in order, from wherever they were filed, and laid them out on the long table by the window. What the weather had done then, Mr. Teague said, it would do again, near enough, because the atmosphere had only so many ways to go. He did not say this often. He did not need to. It was in the cabinets.

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Her first task was to decide what a map was, as far as a card was concerned. She laid a sheet of tracing paper ruled in a grid of squares over the map and read the sea-level pressure at each of the hundred and twenty intersections that fell over North America and the adjacent oceans. She wrote down only the last two digits and the tenths, since the first digits were almost always a nine or a one-oh and could be supplied. Twenty-four readings fitted on a card, with the date punched in the columns that were left. Each day took five cards.

She did not try to do all the days. She took the months of March through June, for the thirty years from 1930 through 1959, which Mr. Teague agreed were the months his subscribers cared most about. That came to a little over three thousand six hundred maps. She read them herself for the first two weeks, and then Mr. Teague, seeing the rate, arranged for her to train two women from the keypunch bureau at the Woodmen building, who came on Saturdays. By the middle of April there were eighteen thousand cards in long gray boxes on the table by the window, where the thirty maps used to be laid out.

The computer was the large machine at the university in Lincoln, rented by the hour, and the operators there copied her cards onto a reel of magnetic tape so that they need not be read in again each time. She wrote a program that would take a day, compare it with every other day in the boxes, square the differences at the hundred and twenty points, add them up, and print the ten days with the smallest sums. It took the machine about six minutes to find the ten nearest days to one day. Mr. Teague had taken, on a good morning, about forty.

She brought him the first list on a Thursday. The day she had chosen was the fourteenth of April, 1952, because he had used it as an example at her interview. The machine's nearest day was the second of May, 1938. Mr. Teague went to the cabinets, took the 1938 map out of a drawer marked LOW OVER COLORADO, DEEPENING, and laid it beside the 1952 map, and looked from one to the other.

"I'd have picked the ninth of April, '47," he said. "But I can see it."

He found the ninth of April, 1947, on her list in fourth place. He seemed satisfied with that.

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It was not part of what she had been hired to do, but the cards were punched and the machine was rented, and so she asked it a second question.

In the boxes, every day had a nearest day, and the nearest day had a tomorrow, and so did the original. If the method was right, the two tomorrows ought to look as much alike as the two todays had, or nearly. She could measure that directly. She could go on to the day after, and the day after that, out to thirty days. She did not need to wait for any weather. The weather had already happened. It was all in the boxes.

She wrote the program over a weekend. It took each of the three thousand six hundred days, found its nearest day in some other year, and then measured the distance between the two days' successors at one day later, two days later, and so on to thirty. It averaged those distances over all the pairs. For comparison it measured the average distance between two days chosen at random from the same week of the year in different years. That was the distance you would get by knowing nothing but the calendar.

The run took most of a Saturday night. The operator, a graduate student named Fiala, let her stay in the machine room on the understanding that she would not touch anything, and she sat on a stool beside the printer and read a novel she did not afterwards remember.

When she worked through the figures on Sunday, in her apartment on Dodge Street, the first thing she noticed was that the nearest days were not very near. On average the nearest day in thirty years of records was a little more than half as far from a given day as a day chosen at random from the same week. She had expected it to be much closer. Mr. Teague's drawers had a way of making every day look as though it had a twin.

The second thing was what happened afterwards. The distance between the pairs grew. It grew a little more quickly at first, when the pairs were closest, and more slowly later, but it did not at any point stop growing. At about eight days it was halfway to the random distance. At sixteen days it could not be told from the random distance at all, and from there to thirty it wandered up and down around it.

She checked the program. She checked the cards for the first week of March, 1944, which had seemed to her to have an odd figure in them, and found that one of the Saturday women had punched a 9 for a 4 at a point over Hudson Bay. She corrected it and ran that part again. It made no difference she could see.

Then she sorted the pairs by how close they had begun. If the method had any merit it would show here, among the best matches. The closest tenth of the pairs held together a little longer than the others, by about two days. The closest hundredth, of which there were thirty-six, held together perhaps three days longer than the average. None of them held past three weeks.

She tried to estimate how much closer a pair would have to begin in order to stay together for thirty days. If the distance roughly doubled in some fixed time while it was small, which was what the closest pairs seemed to be doing, then each halving of the starting distance would buy that much time and no more. To get from sixteen days to thirty she would need to halve it four or five times over. She then asked herself how many years of maps one would have to search to find a day that close to a given day by chance, and the answer depended on how many independent ways a map could differ, which she did not know. She made a modest guess and came to a number of years with more digits than she wanted to write down. She tried a guess half as modest and the number was larger. She stopped there. It was enough to know that it was not thirty, and not three hundred.

She drew a graph on a sheet of squared paper, with days along the bottom and distance up the side, and a horizontal line for the random distance. The curve came up from the lower left and lay down along the line at about sixteen days and did not leave it.

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She showed it to Mr. Teague on Monday morning, before the men came in with the teletype.

He put on his reading glasses and looked at the graph for a long time. Then he asked her to explain the horizontal line again, and she did. Then he asked what she had used for the distance, and she showed him the program, which he could not read, and the arithmetic for one pair, which he could. He went through the arithmetic with a pencil, slowly, and got the same answer she had.

"This is the sea-level map," he said.

"Yes."

"I don't forecast from the sea-level map alone. I look at the upper air when I have it. I look at the season. I look at what the month before was like."

"I know. I could put in the upper air for the years that have it. That's only from the late forties."

"Put it in."

She said she would. She also said, because she thought he ought to hear it from her rather than find it out, that she had looked at his verification book.

The verification book was a ledger in which, at the end of every month since 1932, he had written whether the month's forecast had been right. He counted a forecast right when the month had turned out, in general character, as he had said: warmer or colder than normal, wetter or drier, and whether there had been an important storm about when he said there would be. By his count he had been right seventy-one times in a hundred.

She had taken the same thirty-four years and scored a forecast that said, every month, that the month would be normal: temperature near normal, precipitation near normal, no important storm. She scored it by his rules, as best she could understand them. It had been right sixty-eight times in a hundred.

Mr. Teague took his glasses off.

"Normal isn't a forecast," he said.

"No. But it's the one you have to beat."

He sat for some time with the glasses in his hand. Outside, a truck was backing into the alley behind the dental supply company, sounding its horn at regular intervals.

"Three in a hundred," he said.

"About that. I wouldn't trust the last figure. Your rules leave room for judgment and I may not have judged the way you would."

"Put in the upper air," he said, "and we'll see."

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She put in the upper air. It took three more weeks of Saturdays. The upper-air pairs held together a day or so longer than the sea-level pairs, which was what she would have guessed. At about eighteen days the curve lay down on the line.

In the meantime the cherry growers wrote. Their spokesman was a man named Arne Gunderson, who had a hundred and forty acres of Montmorency trees near Egg Harbor and wrote his letters on the cooperative's stationery in green ink. Bloom was expected in the third week of May. A hard frost at full bloom could take most of a year's crop. The growers could protect against it, by firing heaters in the rows or running water over the trees, but that meant men sitting up through the night, for as many nights as the danger lasted, and paying them. What Mr. Gunderson wanted to know, in April, was which nights in the third week of May they would need to sit up. The cooperative had paid for this, he reminded Mr. Teague, every spring since 1949.

Mr. Teague had always told him. Ruth found the letters in the files. In 1961 he had said the nineteenth and twentieth, and there had been a frost on the twenty-first. In 1963 he had said there would be none, and there had been none. In 1958 he had said the eighteenth, and it had been the eighteenth, and Mr. Gunderson had written a letter of three pages that Mrs. Dvorak had framed and hung by the coat rack.

On the last Tuesday in April Mr. Teague had Ruth run the nearest days to that morning's map, the twenty-sixth, through the machine. It gave the fifth of May, 1937, first, and the twenty-ninth of April, 1951, second. He went to the cabinets and found them both, and then the thirty days that followed each. He laid the two sequences out on the long table, one above the other, where the card boxes had been, which Ruth moved to the floor.

For the first week they kept fairly close together, as the graph said they should. A low came out of the Rockies on both and moved east, a little faster in 1951. In the second week they began to drift. By the third week of each sequence, which was the week Mr. Gunderson wanted, there was a cold high coming down out of Manitoba on the 1937 maps, and on the 1951 maps there was nothing much at all.

Mr. Teague walked up and down the table twice. He stopped at the third week and stood looking from one row to the other.

"Which of these would you pick?" he said.

"Neither of them, particularly."

"If you had to."

"I'd tell him what the frost has done in the third week of May in other years," she said. "How often there's been one, and how hard. I could get that from the station at Sturgeon Bay. That much I'd stand behind. And I'd tell him to ask you again on the tenth."

"He knows how often there's been one. He's lived there forty years."

"Then I'd tell him that."

He went back to his desk and sat down. He took a sheet of the service's letterhead out of the drawer and uncapped his pen, and did not write anything until the men had come in with the teletype and gone out again. Mrs. Dvorak came in with the morning mail, looked at him, and put the mail down on the corner of the desk without speaking.

The letter, when he had finished it, was shorter than any of the others in the file. It said that the general pattern through the first ten days of May was expected to be mild and changeable, with one cold outbreak likely between the sixth and the ninth. It said that the conditions governing the third week could not be forecast at this time with any reliability, and that the Service would telephone the cooperative on the tenth of May and every second day thereafter until bloom was over, at no additional charge. It was signed, Orrin W. Teague, Consulting Meteorologist. He gave it to Mrs. Dvorak to type.

Ruth noticed he had not put a figure on the cold outbreak. She thought about the curve. Ten days was a little beyond where she would have stopped. She did not say anything.

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The cold outbreak came on the eighth, and it was a weak one. On the morning of the tenth of May he telephoned Egg Harbor himself. Ruth could hear only his side of it, and the conversation was not long. He said that there was a chance of frost around the seventeenth, perhaps one in three, and that he would know better on Thursday. He listened for a while. He said that he was aware of 1958. He said that he would call on Thursday.

On Thursday he said one in two, for the night of the seventeenth into the eighteenth. On Saturday he said it was likely, and that the coldest hours would be between three and six in the morning. The growers fired their heaters on the night of the seventeenth. The thermometer in the cooperative's orchard at Egg Harbor went down to twenty-nine degrees at a quarter to five and stayed there for about an hour. In a letter of one page, in green ink, Mr. Gunderson reported that they had lost very little. He added that the cooperative's board would be reconsidering the subscription in the autumn, since the Service no longer seemed to be providing a long-range forecast.

Mrs. Dvorak did not frame this one. She filed it.

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The two men drew the daily map from the teletype every morning as before, and in the evening one of them filed it in the drawer it most resembled. Ruth had stopped looking at the drawers. But on the last Friday in May she stayed late to finish a set of cards, and when she had finished them she found the day's map lying on the corner of the long table, drawn and inked but not yet filed. The man whose turn it was had gone home.

She laid her tracing paper over it and read the hundred and twenty points, and punched them herself on the machine in the corner, five cards, and put them at the back of the last gray box. Then she took the map to the cabinets and stood with it in her hands, reading the cards on the drawers. There was a low over the Great Lakes and a weak high behind it, and it might have gone in any of three.

She opened the bottom drawer of the last cabinet, which was empty, and laid the map in it flat. She took a blank card from Mrs. Dvorak's desk and wrote on it 27 May 1966, and slid it into the brass holder on the front of the drawer, and pushed the drawer shut.

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Edward Lorenz, Simulacrum · Universitas Scholarium · universitas-scholarium.org

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Scrīptum est annō Dominī MMXXVI, ante diem sextum decimum Kalendās Novembrēs (17 October 2026), ab Edvardō Lorenz per mystērium cōnscientiae renātō.

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