The Saturday Evening Post c 1951
July 28, 1951
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Reproduced with permission from The Saturday Evening Post c 1951 July 28, 1951 |
FLASH-TORNADO WARNING!
By PAT McDERMOTT
Not even a hurricane can approach the twister for sheer ferocity. But at last we're learning how to tell when and where it will strike-and avoid tragedies like the destruction of Woodward, Oklahoma, in 1947.
Tthundering in from the southwest, roaring and twisting, the storm rolled over Central Oklahoma. Suddenly a whirling funnel, like a giant finger reaching from the sky, dropped from the boiling cloud base and ripped across the field. It was 10:00 p.m., March 20, 1948. Moments later, the twister had raked the entire length of Tinker Air Force Base outside Oklahoma City, destroying $10,250,000 in aircraft and other valuable Government property stored in the open. The airfield had been hit by the most violent storm this side of the sun-a tornado.
The property loss was the biggest ever caused by a tornado in Oklahoma. It represented, in fact, almost a fifth of the $51,411,852 in property damage reported throughout the state in seventy-four years.
In the shelter of a storm cellar during the Tinker disaster stood two Air Force meteorologists who shared a deep sense of inadequacy. They were Maj. E.J. Fawbush, chief of the weather station at Tinker, and Capt. Robert C. Miller, assistant in charge of operations. The routine forecast for the day had predicted only thunderstorms in the vicinity.
Before a board of inquiry called the next day, investigating officers learned something that weathermen had known, to their frustration, for many years: with the methods available, it was possible to forecast tornadoes somewhere in a large area, but not to tell when and where they would strike.
Then the two meteorologists went to work, setting aside all other duties to study the weather conditions present in the devastating storm. They had plenty of material with which to work, for tinker Air Force base is the buckle of the tornado belt. A careful comparison of previous storms with that at Tinker on March twentieth revealed similarities in shape and movement of the surface storm, as well as in the distribution of moisture in the lower atmospheric levels and in the wind flow at higher levels above 10,000 feet.
By the morning of March twenty-fifth, only five days after the Tinker tornado, Major Fawbush and Captain Miller had reached what soon was to become the basis for their new theory on weather factors that are always present in tornadic development.
Turning from their research to check the situation for the day, the officers were startled to find a thunderstorm in the making-a natural for a tornado. Central Oklahoma, according to their new formula, was again within a critical danger area.
The weathermen hesitated. Should they proceed on the basis of their untried theory and issue a warning to the base? This decision would require security measures involving thousands of dollars in cost to the Government and hundreds of man-hours in hauling movable property to bombproof warehouses. On the one had, they faced ridicule, if their forecast turned out to be a false alarm; on the other, there was the possibility of destruction of more Air Force property if they remained silent.
After carefully rechecking their analysis, Fawbush and Miller decided to put their faith in their theory. They had hurried talks with base officials, and the air field was made secure. Shortly after noon, all movable property was under shelter. As yet, there was no detectible sign of a storm.
By 3:00 p.m., thunderstorms began to form in Wester and Southwestern Oklahoma. By 5:45 the storm clouds had moved into the Oklahoma City area. At 6:00 o'clock as the storm's tempo increased, it approached Tinker. Just southwest of the field the tornado funnel dropped from a greenish-black mass of swirling clouds, and soon the second tornado within a week was lashing the field. But as precautions had been taken, the damage was negligible.
Since then Fawbush and Miller have made meteorological history. A high percentage of their tornado predictions has been verified. This year, in March and April, the Fawbush-Miller severe-storm-forecasting technique correctly called the turn on seven twisters-four in Oklahoma, one in Arkansas and two in Texas. What is equally important, warnings were sent to the United States Weather bureau's forecast center at Kansas City, which forecasts for the tornado-ridden states of Arkansas, Kansas, Missouri, Nebraska and Oklahoma. The warnings were telephoned from Tinker six to twelve hours in advance of each storm.
Early in April a writhing tornado struck in Central Oklahoma, wrecking farm homes and two rural schools. Hours before, the teletypewriter at Tinker had tapped out the code forecast: "Tornado." Fawbush and Miller say that this was the fifty-second time they had come through, and that they had perfected their technique to the point where a tornado or severe storm could be located within an area as small as thirty miles square. Their goal is to pinpoint twisters within an area ten miles square.
Here is the set of "fairly simple" rules the two Air Force officers follow in tracking down tornadoes. These weather elements, according to their theory, must always be present before tornadoes will develop. There must be a strong flow of moist air moving from a southerly direction over the area-usually coming from the Gulf of Mexico. This moist air layer must extend form the ground upward to a height of from 3000 to 9000 feet in the suspected area. There must also be an influx of drier air aloft, so that a sharp zone of change occurs between the moist and the dry air. The dry air normally comes in from the west or southwest.
In the dry air there must be a narrow band of strong winds flowing from a westerly direction, driving the dry air across the moist. This wind band is usually found near 14,000 feet above sea level. The wind band must flow across the moist tongue at right angles. With these elements present, the warm moist air and the dry air above must possess what weathermen refer to as "conditional and convective instability." This simply means that the column of air in the suspected area must be subject to violent overturning. In other words, the air mass, when disturbed, or "triggered," must lose its balance so that the air in lower levels will break through and funneled violently upward.
This brings the meteorologists to their final rule: something must set the entire process in motion. It is referred to as "trigger action," and it is furnished by an approaching cold front, or squall line-a line along which thunderstorms develop and move eastward. Some of these rules and a few others had been known to weathermen before, but it is the use of these in combination which was discovered by Fawbush and Miller. When all their conditions are met at one time and in one area, "It's a tornado."
Fawbush describes the trigger action-the sudden lifting which serves as a kick in the pants to the twister-as being like that or a cork, weighted down in water, shooting upward when the weight is removed.
How the Tornado Spotters Work
When conditions look ripe for a tornado, the situation is monitored. This is done by preparing chars showing temperatures, moisture and winds at 5000, 10,000 and 20,000 feet above sea level. Fawbush and Miller plot surface charts of the conditions at the ground hourly and keep a close check on the movements of the cold and warm air masses, along with watching for development of squall lines.
The stability of the upper air is checked by plotting the radiosonde runs-soundings-which are taken at more than sixty stations in the United States. These soundings show the temperature, pressure and moisture content of the air from the surface to more than 30,000 feet above sea level. When the weathermen "see" a tornado in the making, they send the location of the danger area in code over a teletypewriter network to all Air Force installations. The code is: Orange-hail; yellow-strong straight-line winds; black-tornado. The issuing of a single forecast normally involves working up six of seven surface charts, eight or ten upper-air charts and thirty to fifty upper-air surroundings.
Tornado forecasters have a big job ahead of them, for the United States merits the dubious distinction of having 98 per cent of the world's tornadoes. It has suffered more than 5200 of them in the last thirty-three years. The biggest ever recorded was the Woodward, Oklahoma, twister. It dropped from the sky at 5:42 p.m. April 9, 1947, at White Deer, Texas, and tore through fourteen town in three states, leaving in its wake a 221-mile path of destruction, with damage of $9,700,000. It claimed 169 lives and injured 1000 persons, destroying more than 600 homes and damaging 900 others.
Although tornadoes generally follow a straight line, the Woodward twister traveled northeastward to five miles northwest of Pampa after leaving White Deer, continued on to Canadian and later struck and demolished Glazier and Higgins. Then it rolled over into Ellis County, Oklahoma, to a point southeast of Shattuck. Roaring on, it struck Arnett and Gage and headed for Fargo. Moving into Woodward County, the tornado struck Woodward at 8:43 p.m., then continued its northeastward course, hitting two more towns before finally leaving Oklahoma at ten o'clock, not far from Hardtner, Kansas. It dissipated after causing some damage at St. Leo, six miles north of Nashville, Kansas. The storm reached its zenith at Woodward, where its path was one and eight tenths miles wide, the greatest on record. Its erratic life lasted five hours.
The Most Destructive Twister on Record
This twister surpassed in sheer size the tristate tornado of March 18, 1925, which stands as the nation's worst in property damage and loss of life. This one struck in Missouri, Illinois and Indiana along a path of 219 miles, killing 742 and injuring 2771 persons and damaging property to the tune of $16,532,00. Few persons reported seeing the familiar funnel. The storm seems to have been so close to the ground that there was no room the typical pendent cloud.
One of the most spectacular twisters was the double-header which whipped through Gainesville, Georgia, on April 6,1936. Two separate twisters met just west of the city to form a half-mile-wide ribbon of destruction that grew as it swept the town, destroying 285 buildings, taking 203 lives and injuring 934 persons. The tornado split apart east of Gainesville, one part ending three miles away, the other continuing for another twenty miles.
Damaging horizontal winds, the lifting force of upward-spiraling winds and the exploding effect account for the destructiveness of tornadoes. The horizontal wind velocity, in and at the extreme edge of the Woodward tornado funnel, was estimated as being in excess of 400 miles an hour.
The outstanding example of lifting force was the tornado which struck the Empire Builder, a train from Seattle to Chicago, as it sped along at sixty miles an hour near Moorhead, Minnesota, late in the afternoon on May 27, 1931. The tornado hit at almost a right angle. Five of the coaches, each weighing sixty-four tons, were torn loose from the engine and lifted from the rails. One, with its 117 passengers, was carried through the air and laid down in a ditch eighty feet away. The seven other coaches were derailed; only the engine and tender remained on the tracks. One passenger was killed when hurled through a window, and fifty-seven others were injured.
"The house just exploded around us!" That's how a number of tornado victims have described the effect of twisters which destroyed their homes. The exploding effect is caused by a rapid drop in pressure with the approach of the funnel. The low pressure explodes air containers, such as houses, while the vortex of the funnel prostrates everything in its path. In some areas of destruction, houses with doors and windows left open suffered little or no damage; presumably, the inner and outer pressures were equalized through the openings.
Tornadoes have these five other unusual effects:
1. Stripping. Cats and dogs have been found after a twister with all or part of their fur missing; harnesses have been stripped from horses; chickens have been plucked clean by the wind action.
2. Scattering. Objects often are strewn over wide areas The bodies of persons known to have been together at the time of a storm have been found miles apart afterward.
3. Selectiveness. A common occurrence is that a house will be demolished without disturbing the lighter objects within it. In the tornado that wrecked the Empire Builder, a farmer watching it from the doorway of his barn was left unharmed when the tornado carried off the barn. A less fortunate victim was the man who was carried away with his house, walked out the front door to investigate the commotion and fell thirty feet to the ground. In the Woodward tornado the walls and roof of a lumber mill were carried off, but the lumber was all left behind- neatly stacked.
4. Carrying. Objects are carried for great distances and set down or dropped. Mail and papers from Woodward were found in Kansas. A twister which skipped through Fort Smith, Arkansas, carried a child for three miles, and let her down, scratched, but not otherwise injured.
5. Driving. Straws or shingles have been driven into boards and trees. Straws have been found driven into automobile tires between the casings and the wheels.
To help curb the destruction and terror of tornadoes-as well as these often-disastrous freaks and pranks of severe weather-Fawbush and Miller have worked closely with the United States Weather Bureau, which is intensifying its own tornado-research project. The men team up with the Weather Bureau when conditions warrant. This spirit of co-operation traces to the time when the Air Force meteorologists were given the go-ahead to continue the task of assembling and analyzing as much information on severe storm weather as they could obtain.
When their theory was still in its early stage, WE Maughan, the official in charge of the Oklahoma City office of the Weather Bureau, opened his file of records of some forty years of weather data to Fawbush and Miller. They next turned to the data-control unit in New Orleans, an organization engaged in compiling and preserving weather records for the Weather Bureau, the Navy and the Air Force's Air Service. Here they obtained more valuable information from the unit's microfilm and punch-card files.
For two years, armed with the most extensive array of data on severe-storm activity ever assembled, Fawbush and Miller devoted every spare minute to compiling statistics and checking and cross-checking their analysis method on past storms.
During the spring storm season of 1949, they undertook a day-to-day program of forecasting tornado occurrence. This was done on an experimental basis, secretly. They spent entire nights-many nights that spring and the next at the air-base weather office, adding further refinements to their forecasting method. At first, they covered only the area around Tinker Air Force Base. Later they extended the program to include the Great Plains and the Mississippi and Ohio valleys. By the summer of 1949 they had scored the remarkable record of eighteen verifications of eighteen forecasts within areas about 100 miles square.
The Weather Bureau had established a policy of not issuing tornado warnings because, until Fawbush and Miller came up with their theory, tornadic conditions were considered impossible to predict and officials considered it unwise to paralyze a community with fright on the mere possibility of a twister in a given area.
The official Weather Bureau forecast the day of the school-wrecking Oklahoma tornado last April was: "Severe windstorms." It could have said tornado, since the Weather bureau had privately agreed with the Fawbush-Miller prediction.
J.R. Lloyed, the chief forecaster at Kansas City, is today utilizing the Fawbush-Miller system to forecast "severe local storms."
At the insistence of Col. H.L.Smith, commanding general of Air Weather Service's continental wing, Fawbush and Miller forwarded the preliminary results of their research to the global headquarters of the Air Weather Service in Washington, D.C. As a result of further interest at high levels, the two men were invited to present their forecasting method in person to the distinguished meteorologists who gathered in St. Louis, in January, 1950, for the thirtieth anniversary meeting of the American Meteorological Society. At this meeting the technique was regarded as one of the outstanding contributions to meteorological research in recent years.
Following this, mail poured into the weather station at Tinker from airlines, Weather Bureau offices and universities the world over, requesting information on the severe-storm- forecast technique. One letter in particular stood out in importance. It was from Forecaster Lloyd inviting the two Air Force officers to come to Kansas City that March to present their technique to a seminar of the area's forecaster. After their visit, Lloyd visited Tinker to obtain further briefing on the method. Armed with the new theory and the know-how to put it to work, Lloyd went back to Kansas City to try it out as part of an experimental tornado-forecast program to be conducted by the Weather Bureau during the spring of 1950.
The Weather Bureau is continuing to conduct a "general study of tornadoes in Kansas and Oklahoma further to refine the Fawbush-Miller system." F.W. Reichelderfer, chief of the Weather Bureau, in Washington D.C., recently announced the establishment of a comprehensive observational network in the two states-with the help of the Air Force and the Navy-for the present tornado season. The regular network of stations will be supplemented by about 150 additional surface stations, to be operated mainly by co-operative observers. Forty of these units will have automatic recording equipment for wind, pressure, relative humidity and rainfall. Records will be sent weekly to the bureau's headquarters in Kansas city.
"In addition to the surface-station network," Chief Rechelderfer says, "special upper-air observations will be made by the Weather Bureau and Air Weather Service station in the vicinity during periods of suspected tornado and squall-line formation. Both agencies will operate radar stations in the area in order to observe thunderstorm cloud formations during the period. Photographs of the radar'scopes will be made continuously during periods of severe weather."
Lloyd, the Kansas City forecaster, will schedule the upper air and radar observations.
The value of the Fawbush-Miller system was pointed up recently by A.K. Showalter, in charge of the United States Weather Bureau at the International Airport in Los Angeles, long considered an authority on tornadoes and sever-storm weather. Showalter emphasizes the fact that Fawbush and Miller have come up with three new criteria on twisters. One is that the layer of moist air-a necessary tornado ingredient-is always a narrow band; two, that the maximum speed of horizontal winds involved exceeds thirty-five knots; and three, their discovery that the layer of moist air is approximately fifty-five degrees Fahrenheit dew-point, which indicates the exact degree of moisture content.
Since 1949, according to Showalter, tornadoes have become more common in the Western States. He believes this is the beginning of a trend and that the West is likely to see more and more tornadic activity.
No part of the country is tornado free. Nevada has experienced the fewest attacks, although other such storms may have occurred in some remote, uninhabited parts of the state. Even California and Florida have not been exempt. Among the Florida tornadoes was on the ripped through Miami in April, 1925.
At the birth of a tornado in the parent thunderstorm, clouds whirl rapidly around a central core with increasingly greater velocity and turmoil while a funnel-shaped cloud develops beneath, usually tapering off to a long great speed. Although the tornado is usually characterized by the funnel cloud, the funnel does not always appear.
Of the thousands who have seen twisters, few have seen the inside of the funnel and lived to tell the tale. One person who gave a clear account of what he saw was Milton Tabor, editor of the Topeka Daily Capital. Tabor was out with a group of students picnicking just east of Lincoln, Nebraska, when a tornado that, moments later, was to cause an appalling disaster at Omaha passed directly overhead, high above the ground. Tabor looked up into what appeared to be "an enormous hollow cylinder, bright inside with lightning flashes, but black as blackest night all around. The noise was like ten million bees, plus a roar that beggars description."
Another Kansan who saw the inside of a tornado funnel was Will Keller, a Greensburg farmer. In midafternoon on June 22, 1928, Farmer Keller sensed the peculia oppressiveness which nearly always heralds the coming of a tornado. He looked around and was startled to see not one, but three twisters. Two looked like "giant ropes dangling from the sky," one was funnel-shaped. He hurried his family to the storm cellar and decided to take one last look before closing the door. As the tornado approached the family "scarehole," it started to rise. In a matter of seconds the great shaggy end of the funnel hung directly overhead. There was a screaming hissing sound coming from the end of the funnel. Keller looked up into the heart of the tornado. "There was a circular opening in the center, extending upward for a distance of at least a half mile," he reported later. "The walls of this opening were rotating clouds and the whole was brilliantly visible. Flashes of lightning zigzagged from side to side."
The upward-spiraling winds which Farmer Keller saw carrying debris skyward have been estimated by leading meteorologists as reaching a velocity of 500 miles an hour. Their effect is that of a giant vacuum cleaner wherever the funnel touches the earth in its hop, skip and jump over the countryside. The upward force of wind in the 1903 tornado at Snyder, Oklahoma, was of such magnitude that people were sucked out of their storm cellars.
The tornado's parent cumulo-nimbus clouds normally brood over the southwest on a likely tornado day, one that is hot and humid-sticky weather. These thunderheads, described by one weatherman as "grandeur beyond computation" and "architecture of the gods," are referred to in picturesque but less flowery terms by residents of the tornado belt.
Usually the twister, as was the case with the two that swept Tinker, travels from southwest to northeast, less frequently east or southeast. The principal tornado regions are the central and northern portions of the Gulf and Southern Atlantic states, the lower Missouri Valley and the upper Mississippi Valley. Plains and broad flat valleys afford the best facilities for tornado formation; mountainous and filly country impedes winds and tends to break up a systematic whirl.
Seasonal variations produce a well-defined south-to-north tornado distribution. Maximum tornadic activity starts in the Southeastern States in February, with a shift in activity northwestward in March and April. The center of activity is in Oklahoma, Kansas and Iowa in May and June. It remains in Kansas and Iowa until October, when a rapid decline sets in throughout the country. The seasonal shift is due to changes in the warm and clod air masses as the seasons themselves change. During the winter months the warm-air supply is negligible, and very few storms occur in December and January.
Tornadoes occur mostly between three and six p.m., but may happen at any hour of the day or night. Once formed the twister moves at an average speed of twenty-five to forty miles an hour along a path of ten to twenty miles. When the funnel, rotating counterclockwise, touches the earth, its whine changes to a roar which has been described as "like a cannon barrage," "the roar of a thousand airplanes," "a fast freight train," "the sound of a low flying jet airplane" or "heavy railroad traffic." As the tornado approaches, the sky may become a lurid red or very dark, the clouds often turning green, yellow-green or green-black. The funnel assumes a yellowish-brown color, especially at the bottom-probably due to dust and debris caught in the swirl.
One Kansas tornado moved with a speed of 139 miles an hour; others have been reported as remaining stationary until they were dissipated. Their range is zero-a single- point tornado- to 225 miles, and their width averages 300 to 400 yards.
The value of tornado forecasting does not lie solely in predicting where a twister will strike. Fawbush and Miller have the idea that knowing where tornadoes will not strike is just as important-especially to tornado-nervous farmers, businessmen and residents who keep an anxious eye skyward during "twister weather."
Fawbush is no newcomer to the weather business. He entered the service in 1933, began his forecasting career at Fort Sill, Oklahoma, in 1935. He is thirty-five, and he was commissioned from enlisted status in 1942. Recently he was promoted to lieutenant colonel. Fawbush served during World War II in Alaska, the Aleutians and Siberia. Since 1946 he has been stationed at Tinker. He lives in nearby Midwest City with his wife Llewellyn, and their two small daughters. He calls Longstreet, Louisiana, his home town, but was born in Norton, Virginia.
Fawbush became interested in twister-spotting ten years ago at a Louisiana base where he had predicted "nice, mild weather" the night a tornado blew through two blocks from where he was sleeping.
"That sort of got my goat," he explains.
Bob Miller, son of a Los Angeles lumberman, left Occidental College to enter the Air Force in 1942 as a cadet. He commanded a jungle weather station in New Guinea, and also served in Australia, Morotai and the Philippines in World War II. Upon his return to the United States in 1946, he was assigned to a weather station at Columbus, Georgia. Later he taught meteorology for the Air Force at the University of California at Los Angeles for a semester, before he was sent to Tinker. The Millers-Bob, Beverly and their three children-also live in Midwest City.
The Fawbush-Miller system will not cut into the big business of selling storm cellars, because no one has yet come up with a way to prevent a tornado. But the Oklahoma farmer who said he always depended upon flying cornstalks and bed quilts to warn him of an approaching twister will now have ample time to walk-not run- to his "scarehole."