Shovel, shovel, skid and trouble. Are they what's in store for our fair city this winter? The past four years Washington has endured everything from the coldest winter and the second greatest snowstorm of all time to the hottest summer and a few tropical storms thrown in for good measure. To many folks it has seemed as if the extreme has been the norm. Now a lot of us are worried that after our hottest summer ever, Mother Nature will balance the climatological ledger with an abnormally cold winter. Some are already gearing up for such a winter on the basis of data such as caterpilar coats, trick knees and flea migration. While some of these "old reliable" methods may indeed prove correct, recent gains in weather forecasting can provide data of a more scientific -- and more accurate -- character.
Day-to-day forecasting has always ben a rather inexact science, but it is becoming more accurate all the time. Long-range forecasting, as recent as it is, is providing us with some fascinating and frightening long-term weather possibilities.
No one can offer absolute guarantees, but weather forecasting has progressed to the oint that even the cautious among us are willing to go out on a limb with at least a few predictions for the weather in months ahead.
So come on out on that creaky limb, and I'll tell you what I see in our future . . .
The winter of 1980-81 will be a rather easy one for Washingtonians. The three winter months (December, January, February for meteorologists, Dec. 21-March 21 for astronomers) will have temperatures slightly above "normal." That adds up to a milder than average winter. There will be quite a bit more rain than snow and the rains will often be warm rains. There will be a number of "cold snaps" but they will not be of the persistent bone-numbing variety of the "winter of '76-'77" and there will be several very mild respites of balmy, almost shirtsleeve weather, especially in mid-January.
The toughest part of the winter, from the standpoint of snow and ice, will come toward the end of February and the beginning of March after which we will slide into a pleasant, if cooler than normal, spring.
Now the qualifiers. Much of the above is my own personal hunch based on what I know of our recent weather patterns. Part of the above is based on what meteorologists and other scientists are learning about our long-range weather patterns and our ability to predict what will happen one, three, six months . . . even six years from now. General seasonal forecasts have some scientific basis, though specific predictions six months hence are the stuff of dreams.
Before I let you in on the secrets of how my winter outlook was divined, let's look at some of the things that govern our weather and recall some of the features of recent weather hereabouts.
I mentioned earlier that we are living in a time when extremes seem to be the norm. This past summer was a prime example.
The Washington summer of 1980 was the hottest ever recorded. June was about average but July was the hottest July and, until August 1980 came along, the hottest month. Three days in July were above 100 degrees, 20 days had temperatures of 90, or more, most nights the temperature only dipped to the mid-70s.
August 1980 stands alone in Washington weather records for monthly heat reacords, an average temperature of 82.8, a record 22 90-degree days, to say nothing of the humidity. September 1980 barely missed being the hottest September, second only to September 1881.
Comparing Washington's weather today to that of 100 years ago is not quite fair. Man has changed the weather of his cities. The mass of concrete and asphalt stores huge amounts of heat and makes our cities in summer hotter than they were a century ago.
Dr. Helmut Landsberg, world-renowed climatologist at the University of Maryland, says that our summer record string of 22 90-degree days in a row would only have made a modest 14 90-degree days 100 years ago. Yes, air conditioning bills are less in the country.
This hottest summer followed, by three years, our coldest winter, the first of three brutal winters that glaciate much of North America. Three winters ago, you may recall, it snowed in Miami; the temperature plummeted to 30 below zero in Cincinnati and was below freezing for almost 100 straight days in parts of Minnesota. By winter's end in 1978, almost 20 feet of snow had fallen on poor Buffalo, N.Y., and the white stuff had to be loaded on rail cars headed south to get rid of it.
Two winters ago Chicago bore the brunt of yet another brutal winter. It was Chicago's coldest winter ever, and the snow and cold created tremendous hardship from New England to the Northern Plains, where old-timers could not remember more severe winter weather. Then last winter everything changed and most of the country enjoyed an easy winter.
All this serves to point up what many of us feel -- the wheather of late has become more erratic. The extreme is the norm. More records, more snow, more floods, more heat waves, more cold waves. No one knows exactly why we have had such weather extremes or if our weather will settle down, but we do know that the jet stream, a river of high-sped air about eight miles above us, has been up to some wild antics the past few years.
The jet stream occurs at the boundary of the two great air masses that govern our weather in the northern latitudes -- the polar air mass to the north and the tropical air mass to the south. The cold polar air expands and contracts as the seasons progress and the jet stream at its southern boundary migrates south or north. The greater the temperature contrast from north to south, the greater the amplitude of the undulations of the jet stream.
Over the past few years these undulations, or waves, in the jet have been of unusually large amplitude, sweeping the jet farther north and south. As a result there has been a tremendus contrast in weather and extremes in weather. In winter cold air building in the Canadian Arctic was pushed steadily south into the United States. In 1977 and 1978 the main push was into the Great Lakes, the northeast and the Ohio valley.
Two winters ago the cold pattern shifted westward. The wnter of 1978-1979 was brutal in the western plains but rather easy here until 18 inches of snow fell on us in February 1979.
What was most unusual about these past winter weather patterns was their persistence: day after day unrelenting cold poured into the United States. As we recall only too well, last summer's hot weather patterns were equally persistant.
These difficult summer and winter weather patterns appeared to be self-feeing. During the winters of 1976-77, 1977-78 and 1978-79, extreme cold produced a widespread and persistent snow cover that reflected some of the sun's energy back into space. This prolonged the cold.
Last summer also provided a self-feeding mechanism -- self-feeding on heat, not cold. The hot air mass built in the Plains in June while the jet was further north than normal, a situation that was almost the exact opposite of the past winter's pattern. Day after day the sun bore down on the country, and with cool air far to the north, there was little temperature contrast from Texas to the Dakotas. Without temperature contrast, there was no way for rain storms to form and the heat was then coupled with drought.
The movement of the great global air masses and the jet stream may explain some of the weather extremes of the past few years. But what is causing the jet to be so "wild and crazy" and to exhibit such large amplitude and pesistent undulations? Quite frankly, no one knows for sure. It may be a routine variation in the currents of our ocean of air that is of no lasting significance. Or, more ominously, it could be the first signal of an important, possibly irreversible change in the global climate.
The atmosphere and our weather is an amazingly complicated affair. A variety of gases in various concentrations envelope our 8,000-mile-diameter globe to a depth of only about 20 miles. Because our world is made of varying materials (trees, soil, rock, water, sand, etc.), the sun's energy is absorbed or reflected differently in different latitudes and different regions.
Changes in the climate and long-term weather patterns are very subtle, but we can speculate about some of the possible causes.
First, the oceans. They exert a tremendous influence on our weather patterns. Their water, which covers 75 percent of the earth's surface, absorbs and stores much of the sun's energy that strikes the earth. Just as there are large moving masses of cold and warm air in the atmosphere, so too are there large masses of cool or warm ocean water. The interaction of the cool or warm ocean areas with the atmosphere may affect the location of the jet stream and as a result affect our weather.
For many years Dr. Jerome Namias of the Scripps Institution of Oceanography in La Jolla, Claif., has been studying the movement of these "anomalous" regions of cool and warm water in the Pacific Ocean. He believes that in regions where there is a contrast of water temperatures, storms are more likely to form. These sotrms, in turn, would tend to form a valley or trough in the jet stream. Because the ocean temperature patterns usually are very persistent, the features induced in the jet stream would also be persistent. Because of the wave motion of the jet, Namias says, Washington winte weather could be determined by the water temperature patterns of the ocean half way around the globe.
Second, consider the sun. Changes in the sun's energy output also are likely to have a dramatic effect on weather and climate. A NASA spacecraft now in orbit measures the energy output of the sun and examines solar storms and the giant solar flares. So far there is no evidence that the total energy output of the sun has been changing over the years, but within the past few months, measurements from the NASA spacecraft have shown a slight fluctuation in the sun's energy output. Dr. Richard Willson of the Jet Propulsion Laboratory, writing recently in Science magazine, reported a variation of about 0.1 percent in the sun's energy output over a one-to-two-week period.
Several years ago Dr. walter Orr Roberts, now of the Aspen Institute in Boulder, Colo., showed a correlation between the passage of solar sectors (regions of polarity changes in the sun's magnetic field) and the strength of northern latitude storms. Dr. J. Murray Mitchell, senior research climatologist with National Oceanic and Atmospheric Administration, has also found a correlation between the 22-year solar cycle and a 20-to-22-year drought cycle in the western United States. Mitchell hasn't found the physical link between the sun and the drought cycle but thinks it might be related to changes in the polarity of the sun's magnetic field (it reverses polarity every 11 years, so a complete cycle is 22 years), and a coupling with the earch's magnetic field. This in turn may determine the depth to which energetic solar particles can penetrate our atmosphere.
If the particle flux or solar wind reaches deep enough into earth's atmosphere, it could heat the stratosphere enough to affect our weather patterns.
The champion of the solar-weather link is Dr. Hurd Willett, professor emeritus of meteorology at the Massachusetts Institute of Technology. He thinks many variatons in our seasonal weather patters are attributable to cycles or patterns in the output of solar energy.
Many other weather experts see no sun-climate link. Dr. Alan Robock, climatologist at the University of Maryland, says all our recent extremes may be just a natural variation in our climate and weather. The atmosphere, in his view, is never "normal" -- even three severe winters in a row are not abnormal behavior for such a variable system as our atmosphere.
Finally, the weather extremes of the past few years could be a first sign of grave changes in the climate caused by human activity. Since the Industrial Revolution started and the combustion of fossil fuels (coal, oil, gas) began in the last century, we have increased the carbon dioxide level of the atmosphere by about 15 percent. Dr. Gordan J.F. MacDonald of the Mitre Corporation in McLean is afraid a warming of the atmosphere may have already started because of the so-called "greenhouse effect," in which a carbon dioxide-rich atmosphere lets in the sun's energy but then traps the heat.
Such a development on earch would lead to a global warmup. According to MacDonald, we may live to see the polar ice caps begin to melt and the oceans begin to rise because of the carbon dioxide we have added to the atmosphere. Some scientists believe that global warming, if it happens, will occur unevenly, heating some regions more than others and further increasing the temperature contrasts between the poles and the equator. If so, we may be in for a lifetime of weather where the extremes are the norm.
My own personal hunch, which is not a whole lot better than your hunch at this point in our study of climate change with its many theories and few answers, is that our recent weather extremes are not just "one of those things." I believe they result more from things happening on the sun, though, rather than from some catastrophic change in our weather because of the increase in atmospheric carbon dioxide.
Sunspots usually increase gradually in number as the sunspot cycle progresses. The most recent cycle departed dramatically from this pattern: there was little increase in the number of sunspots for several years and then, beginning in the summer of 1978, the spots multiplied at an unprecedented rate until last December they reached the second-largest number ever recorded. This unusual solar cycle may be the cause of the strange weather we have had the past four years. Two to four winters ago the sun was unusually quiet; this summer it was unusually active. There may be a connection to our past cold winters and hot summer.
Looking at some of the goings-on on the sun, the progession of the jet stream patterns of the past few winters, the fall weather patterns which have now established themselves, the warmth of the summer just past and finally the mathematical probabilities of yet another frigid turn of the year, I look for a mild winter.
Does that mean you shouldn't bother with the snow tires this year or forgo purchasing a new snowblower? No. Long-range forecasting is, at best, very risky and any outlook is given with no money-back guarantees. In addition to an easy winter, I will also say, as if I haven't gone out on a the limb far enough, that as the sun quiets down, our weather of extremes will also settle down over the next few years.
Finally, I would almost guarantee that next July, August and September will be cooler than this year, but just to be sure . . . may I suggest you stay tuned?