Forecasting the Weather a Year Ahead
August 1937 Popular Mechanics

August 1937 Popular Mechanics

[Table of Contents] Wax nostalgic about and learn from the history of early mechanics and electronics. See articles from Popular Mechanics, published continuously since 1902. All copyrights hereby acknowledged.

If someone asked me "what does a meteorologist look like?," I would refer him to this photo in the August 1937 issue of Popular Mechanics magazine entitled "Forecasting the Weather a Year Ahead." Having been heavily involved in model aviation (and for a brief period full-scale aviation) all my life, I have always had a keen interest in weather phenomena. In fact, when I enlisted in the U.S. Air Force, my "guaranteed" job was to be a Weather Equipment Specialist. In a long list of other disappointments that would follow my next four years, I was informed while in Basic Training that that "guaranteed" job was really not available. Long story short, I ended up being an Air Traffic Control Radar Repairman instead. Anyway, in 1937 there were no digital or even serious analog computers available for modeling and predicting weather events. Meteorologists assimilated data provided via teletype from around the country and large bodies of water, and generated maps and forecasts based thereupon. Long-term trends had already been discovered based on ocean temperatures and jet stream characteristics. Water and atmospheric sondes measured and reported various parameters useful in predictions. It is amazing they were able to do such a good job. I still follow the weather closely today, and know that even with vastly more sophisticated measurement, reporting, and data analysis tools, getting the weather right for more than a couple days is rare. Pilots are still taught to observe and draw their own conclusions about weather using visual observations and knowledge of atmospheric behavior. We're not much closer today to having meaningful year-ahead weather forecasts as we are to a flying car in every garage and a personal tokamak to power every house.

Forecasting the Weather a Year Ahead

Everyone wants to know what the weather will be like tomorrow. Weather wizards who are developing the science of air-mass analysis can tell you not only that but they can make predictions for the next two or three days that are correct nine times out of ten. Air-mass analysis is contributing amazingly to the accuracy of weather forecasts.

Now there is a possibility that the same science may help to foretell the general climate a whole season in advance. That means that late in the summer, for instance, forecasters will be able to say whether a cold wet winter or a comparatively mild one may be expected. Advance information like that has been a major goal of meteorology for a long time. Such a head start on the weather would mean tremendous savings to industry.

It is too early in the year to predict next winter's weather, although the forces that will control it are being studied already. But the conditions that brought on last winter's floods and unusual conditions were scrutinized as early as last summer. Last October Dr. Irving P. Krick of the California Institute of Technology warned citrus growers that they could expect unusually cold weather and heavy frosts during the winter season. He based his forecast upon a queer shift in what he calls the semi-permanent atmospheric boundaries that control the general climate in the United States.

Normally one of these boundaries lies just east of the Rockies and the other hovers over the Atlantic a few hundred miles at sea. The boundaries mark the limit of the fairly stable cold continental air mass and separate it on both sides from warmer and more moist air masses over the oceans. Frequently these boundaries shift back and forth several hundred miles in a few days but their average geographical positions seem to be pretty well fixed. Ordinarily, oncoming Pacific air provides a mild winter along the west coast, and the cold continental air in the middle west and in the east provides a cold winter climate.

What Dr. Krick noticed was that the cold continental air mass had shifted to the west something like 500 miles and for a time it remained more or less fixed in its new position. The western boundary had moved out over the Pacific. This would prevent warm ocean air from reaching the west coast and led to the forecast of a cold winter for the citrus growers. At the same time, the eastern boundary of the continental air mass had moved inland as far as the west slope of the Appalachians. Put in simple words, this suggested that the forces influencing weather had shifted west for the time being and that in anyone place the weather conditions that normally occurred a few hundred miles to the east might be expected, modified by local conditions.

That meant unusual weather everywhere. In the east, exposure to the warm Atlantic air indicated a relatively warm winter with thaws and floods. That is precisely what happened.

The displacement of the continental air mass also seems to account for the devastating floods along the Ohio and Mississippi rivers. The thaws west of the Appalachians contributed their share and the same displacement of the continental air mass that caused them also re-routed the storms that normally travel from west to east along the northern border of the country. Starting out over the Pacific, the storms encountered the cold continental air sooner than usual and were shunted far to the south where they described circular tracks across Mexico and the Gulf and finally made their way up the Mississippi valley. In crossing the Gulf the storm centers picked up tremendous quantities of moisture that were later precipitated in the flood area.

The same westward shift also provides a reason for the drought in the middle-western dust bowl last summer. Ordinarily heavy showers occur east of the Rockies along the zone of activity that marks the western boundary of the continental air mass. When the boundary moved to the west the showers fell as usual, but last summer the boundary happened to lie over Utah and Arizona instead of the states more to the east. Those states were robbed of their normal summer rains, resulting in the drought.

Even if this extension of air-mass analysis is going to provide the key to accurate long-range forecasts, Dr. Krick won't be ready to depend upon it until the reasons for the behavior of the air masses can be found. One explanation may be found in the fact that last summer unusually high temperatures were recorded by sea-water thermometers in the north Pacific. This suggests that the warm sea water in turn warmed the air above it, allowing the air to pick up more moisture than usual. In turn, this made the air lighter than it is ordinarily. Humid air is always lighter than dry air. The result was that the cold dense air of the continental air mass was able to flow in under the warm air, shouldering it upward and extending its own cold influence clear to the west coast. Ascending warm air usually meets colder temperatures in the higher altitudes and this results in condensation and then precipitation. It may be that the real key to the climate, at least for part of the country, may be found in the sea-water temperatures of the north Pacific.

Right now air-mass analysis is serving the weather bureau, air lines, motion-picture studios, and scores of different industries. By knowing what the weather will be like a day or so in advance, motion-picture studios are able to plan their outdoor camera schedules ahead of time with fair certainty. Real-estate concerns depend upon weather forecasts to plan their week-end activities and advertising, and even wayside eating stands regulate their orders for food depending upon whether the forecasts are for fair or dull weather.  

Air-mass analysis got its start when it was learned that large portions of the earth's atmosphere, covering as much as several million square miles and extending to heights of six or seven miles, have rather uniform characteristics. Usually an air mass from the polar regions is extremely cold and dry while an air mass moving up from the tropics is warm and humid. These air masses frequently collide and the dissimilarity of the air in the two masses results in atmospheric disturbances along the boundaries that separate them. Cold air is heavier than warm moist air, so the polar air mass begins to slope in under the warm mass, pushing its outer fringe upward. This slope between the cold and warm air is usually at the ratio of one to 100, so that if one were standing in cold air 100 miles from the line where cold air is meeting warm air at the surface, he would find warm air one mile above him.

There is a continual struggle going on between these polar and tropical air masses or currents. The usual result of each meeting of two different masses is clouds of precipitation, caused by the boosting upward of the warm air to altitudes where the moisture starts to condense.

This is a rough rule-of-thumb outline of the air-mass system. To accurately gauge the weather by it, forecasters have to assemble on charts hundreds of reports coming in by radio and telegraph from airplanes, ships and ground weather stations. Each air mass is different, but on the charts the migrations of the masses may be plotted several days ahead of the time that they reach a district, and in that way the probable weather disturbances and their probable times of arrival are anticipated.

"Climate is merely a summation of weather, and weather from day to day results from disturbances along the atmospheric fronts," says Dr. Krick. "This gives us a start in attempting seasonal weather forecasts, for if the semi-permanent atmospheric fronts during the seasons of the year can be anticipated the kinds of weather associated with them may be determined, and thus the climate of the region.

"Although the climate of the earth is not changing appreciably over long periods of time, certain departures from the so-called normal weather occur from year to year, such as the floods in the Ohio valley and the frosts in southern California that happened last winter. These developments are explained and in fact were anticipated by a shift in the semi-permanent fronts that were observed in the spring of 1936.

"When the causes of such shifts in the principal atmospheric boundaries can be determined we shall be able to anticipate long in advance the abnormalities that result in seasonal weather. Then these predictions should be just as accurate as the present forecasts of the day-to-day changes in the weather."

Measuring snow to determine quantity of water content.