November 28, 2002

Unusual Weather Patterns Shape the 2002 Growing Season

A warm, dry, relatively uneventful winter preceded the wildly erratic weather of the 2002 growing season, says John Enz, North Dakota State University agricultural climatologist.

According to Enz, west-to-east winds prevented both arctic and tropical air from invading the Northern Great Plains, resulting in a very mild January. Average temperatures were 8 to 10 degrees above normal. The warm weather continued into February, with temperatures reaching 40s, 50s, and even 60s in some locations throughout the state.

Cold arctic air embraced the plains in the beginning of March, crushing expectations for early planting. Average March temperatures were lower than February’s, and also lower than January’s across western North Dakota.

"April roared into North Dakota like a herd of buffalo dragging our lost winter weather," Enz says. "With temperatures dropping rapidly, heavy, wet snow fell across the state from April 1-4. A weather roller coaster ensued as a succession of warm tropical and cold arctic air masses moved through the state, producing wide temperature variation along with numerous rain and snow showers."

Enz notes that memories of dry spring conditions prevalent from 1988-1993 returned as dry weather persisted throughout May. Snow accounted for most of the month’s precipitation ranging from 3 to 19 inches in the west-central and northwestern regions. Average May temperatures ranged from 4 to 10 degrees below normal, however, these averages hide large temperature variations ranging from 10 degrees to over 80 degrees. Record lows were set in the northern half of the state following the snow, and on May 24 significant crop damage was suffered in the Red River Valley as temperatures dipped as low as 23 degrees in some areas.

"The remainder of the growing season was a tale of too little or too much water," Enz says. Southwestern and south-central North Dakota received very little precipitation throughout the summer, which contributed to four straight weeks of high temperatures in that region. On June 28 and 29, Mandan reported 107 and 109 degrees, while Bismarck had 104 and 111 degrees. Exceedingly high temperatures ceased briefly, as the first significant rain came in mid-July.

Other areas had abundant rainfall in the summer months. Major storm systems brought excessive precipitation to northern North Dakota and the Red River Valley, disproving earlier predictions of drought. At Walhalla and Cavalier, 4.51 and 5.75 inches were reported respectively as totals for June 9,10, and 11. These storms created extensive flooding in the Red River Valley and northwestern Minnesota. In addition, scattered locations throughout the state reported July totals of 5 to 8 inches. Verona actually topped 9 inches, setting a new record for the month of July.

During August, the south received less than 1 inch of rainfall, but most of northern North Dakota received 2 to 3 times the normal amount of precipitation. The 8.62 inches reported at Hansboro is the greatest on record since 1908.

Outside of northeastern North Dakota, rainfall was considerably lower than normal in September. Yet, cloud cover and low temperatures in October created poor drying and harvesting conditions.

Contemplating the unusual weather trends in past months, many are wondering what to expect in the future. Enz notes that the National Climate Prediction Center is predicting an El Nino condition for this winter. El Nino has typically generated warm, dry winters in the Northern Great Plains, minimizing soil water recharge.

However, Enz cautions that long-term forecasts including those found in the Old Farmer’s Almanac should not be considered accurate weather predictors. He says, "…as with all weather outlooks, you should be aware that anything can happen."

For more information, refer to the 2002 Growing Season Summary for North Dakota, at http://www.soilsci.ndsu.nodak.edu/Enz/index.html, compiled by Enz and Barbara A. Mahoney.

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Sources: John W. Enz, (701) 231-8576, john.enz@ndsu.nodak.edu
Barbara A. Mahoney, 231-8574, barbara.mahoney@ndsu.nodak.edu
Writer: Teresa Oe, (701) 231-2044, teresa.oe@ndsu.nodak.edu
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsu.nodak.edu

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