November 29, 2001

2001 Growing Season Mostly Wet

Total rainfall for the April-September 2001 growing season was above normal in about 80 percent of North Dakota, continuing a run of relatively wet growing seasons that began in 1993 when the last drought was broken, according to a report by John Enz, agricultural climatologist in the North Dakota State University soil science department.

Enz cautions that the term "normal" as used in climatology and meteorology is often confusing. Normal is defined as a 30-year average for the preceding three complete decades and is used to characterize average climatic conditions. Unfortunately, he says, its use often implies that deviations from normal are therefore abnormal. This is not true, says Enz, because the strong continental climate of the northern Great Plains typically causes temperatures, precipitation and other elements of climate to vary widely from day to day or week to week. The 30-year average is useful to mathematically compare years or locations by masking day-to-day weather variation.

In 2001, April rainfall ranged from 1 to 4 inches across North Dakota, or from about 50 to over 200 percent of normal. Most of northern, central and extreme southwestern North Dakota was dry. May rainfall totaled a half inch in the west, increasing steadily to more than 4 inches in the east. Amounts were below normal for the entire western half of the state, but the northern Red River Valley continued wet with 125 to 200 percent of normal rainfall.

In June, rain continued in southeastern North Dakota, causing many producers to check out prevented planting insurance options. Not far to the north, however, eastern counties had a respite from the rain. June rainfall was extremely variable across the state. Most of western North Dakota received above normal rainfall with several locations reporting record or near record amounts. Hansboro in northern Towner County had a record-smashing 12.59 inches for the month, over 400 percent of normal. Enz says the presence of 1993, 1994, 1998 and 2000 in the list of 10 greatest June rainfall for several locations illustrates the wetness of the past decade.

June also produced severe weather, with thunderstorms that produced high winds, heavy rain and hail that filled underpasses and created hail drifts hitting Bismarck on June 9. These storms continued on through southeastern North Dakota. Later in the month hail wiped out many crops near Hettinger and other southwestern locations.

July began with generally warm, dry weather. Dry conditions stressed crops in the east central region, but the dry weather disappeared as a series of showers and severe thunderstorms moved across the entire state, often producing high winds and heavy rains. NDSU plant pathologists reported that after July 11 weather was overwhelmingly favorable for scab in small grains in the northern half of the state. Ample rain, high relative humidity and near normal temperatures created increased potential for disease in small grains and cercospora in sugarbeets. However, these same conditions were favorable for most longer season crops.

The storms disappeared in August. Western North Dakota received less than 25 percent of normal August rainfall. Only the east central region received above normal rain, when severe storms with damaging wind and heavy rain struck. Hillsboro was the hardest hit, with winds approaching 100 miles per hour causing major damage. Dry weather persisted over much of the state through September, producing ideal harvest conditions.

Autumn precipitation is important in North Dakota because it helps recharge soil water. Many areas received beneficial rain in September and October, but only about an inch of rain fell over most northern areas. However, a major snowstorm moved across the northern half to two-thirds of the state in late October. Based on snow amounts, water content probably ranged from a half inch to 2 inches, which infiltrated as it melted. Stored soil water will still be short in the north central and northwestern areas. Recharge there will depend on snowfall, frost depth, snowmelt infiltration and spring rainfall.

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Source: John Enz, (701) 231-8576, john.enz@ndsu.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu

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