Weather is not a ‘cycle’

Graphic by Troy Becker / Forum Communications Co.

John Wheeler – WDAY and WDAZ chief meteorologist

Wet or dry, hot or cold, every year can be different

Until recently, the most outstanding weather in North Dakota history was the drought of the 1930s.

From 1929 to 1940, the weather was extremely dry most of the time. Sometimes, the weather would briefly turn hopefully wet, but the drought always returned.

The winter of 1936-37 produced a record (for the time) snowfall of 82 inches. When that snow melted, instead of major flooding, the Red River at Fargo crested at 10 feet. Not 10 feet above flood stage, but 10 feet – 8 feet below flood stage and 31 feet below the 2009 record flood.

Because the Red River had been reduced to a series of stagnant, muddy pools with no real flow at all, the spring runoff from a record snowfall was just barely enough to get the river flowing again.

Meanwhile, Devils Lake, the largest body of water in the region, was by 1940 reduced to a few acres of shallow, brackish pools surrounded by a vast beach of wind-blown alkaline sand.

Think for a moment about how our region would be affected by such conditions today, given our urban population increases and contemporary water uses.

Now, fast-forward to the present. Instead of being parched and dusty, our soils have become perpetually saturated. Instead of hardly flowing at all, our rivers are now routinely out of their banks, and severe flooding has become an annual spring nightmare. Devils Lake is 53 feet higher than it was in 1940, and has grown from about 13.4 square miles to 327.8 square miles.

In complete contrast to the drought of the 1930s, the weather lately across the Red River and Devils Lake basins has been wet, wet, wet; the opposite of drought. Interestingly, there is no word in English for the opposite of drought. The phrase “wet cycle” is commonly used, but this implies a periodicity that is not there.

Climate records from tree rings and lakeshore cores tell us that large-scale droughts such as the 1930s and persistent flooding like the past 19 years do not happen with any kind of simple regularity, if there is any regularity at all.

An English farmer’s proverb goes, “There is no debt so surely met as wet to dry and dry to wet.” But it is important to understand that the dry years and the wet years do not even out over time. Our climate is not cyclical.

By definition, “normal” weather is not “the way weather is supposed to be.” Actually, “normal” weather is only the average over the three previous decades. And every new decade, these “normals” are recalculated to reflect ongoing trends.

The average annual precipitation (rain and melted snow) over 130 years of kept records is 21.36 inches. From 1881 through 1992, the average was 21.36 inches, but during the past 18 years, it has risen to 25.26 inches, a gain of 22 percent. During the drought years of 1929 through 1940, the average was a mere 15.46 inches, which is 30 percent less than the other 118 years. This illustrates numerically the havoc that happens when either dry or wet weather continues for a multiyear period.
The Dust Bowl was 70 to 80 years ago, about the span of a human lifetime. A young person in the 1930s would have had difficulty imagining how much our climate would be changing. Likewise, within the context of our ongoing wet weather, it is easy to look back to the 1930s drought as a historical aberration. But we all need to recognize that each of these phases are really just samples of the way our climate irregularly swings back and forth.

When you live with water, the years go by, and it is easy to get used to a certain set of circumstances. “We’ve always had enough water.” “We’ve never had a flood here before.”

But this use of always and never are taken from a perspective that does not include enough years. In order to appreciate our region’s weather, we need to develop a much larger perspective.

John Wheeler – WDAY and WDAZ chief meteorologist