Climate Summary - 1997
Minnesota Climatic Conditions Leading to the Spring Flooding of 1997
During his opening remarks at a press briefing on April 25, 1997, Director Kent Lokkesmoe of the DNR - Division of Waters said; In the historical record, we have not seen a comparable sequence of such extreme precipitation events which have affected so much of the Red River basin in a single over-winter season. This single sentence describes the climate scenario leading to one of the greatest natural disasters in Minnesota and North Dakota history. Cataclysmic April flooding along the Red River of the North and the upper reaches of the Minnesota River forced thousands from their homes and caused hundreds of millions of dollars in damage.
The winter of 1996-1997 brought the greatest snowfall totals ever recorded over large areas of the Red River and upper Minnesota River basins. Not only was the snowfall noteworthy in its intensity, but also in geographical extent. Six to eight blizzards, and numerous smaller snowstorms, dropped over six feet of snow over northwestern and west central Minnesota. Some areas received an improbable (for the region) eight feet of snowfall. As the spring snowmelt season approached, thigh-deep wet snow filled the landscapes of the eastern Dakotas and western Minnesota (not to mention the towering snowdrifts).
The conditions described above were enough to generate overwhelming flooding. However, a major winter storm hammered the region from April 4 to April 6 and further exaggerated an already dire situation.
Growing Season Weather
Sharp contrasts marked the 1997 growing season. Following the heavy snows of Winter, the spring weather suddenly turned dry. This climatic flip-flop led to one of the driest springs ever recorded in some areas. With concern growing for an imminent drought, northwestern, central and southern sections of Minnesota were abruptly soaked by one of the wettest Julys ever experienced. Only northeastern Minnesota missed the July deluge, and the continued dryness reduced that region’s streams to a trickle and enhanced forest fire potential.
After the early spring rain and blizzard of April 5 and 6, the weather was cold and dry for the remainder of the spring season. From early-April to late-June, much of Minnesota experienced below normal precipitation. The driest areas were found in east central, and central Minnesota. In some Minnesota communities, April 1 - June 23 precipitation totals were near or below all-time low precipitation records. Cool weather mitigated the extreme dryness somewhat by reducing evaporation demand.
The dry spell ended abruptly in the Northwest when heavy rains drenched many counties on June 22-24. Heavy rains returned to Minnesota on June 28-29 when a complex of thunderstorms brought downpours to portions of northwestern, central, and southwestern Minnesota.
On July 1, for the third time in roughly a week, heavy rains fell across portions of northwestern and central Minnesota. The severe thunderstorms that brought about the intense rains, also caused extensive wind damage throughout central and east central Minnesota. Hail-damaged fields, particularly in western Minnesota, became an increasingly common sight throughout late June and into July. The heavy rains continued through July in central, east central, and southeastern Minnesota.
How wet was the summer of 1997? For the period June 24 to August 4, large areas of northwest, north central, central, and east central Minnesota were near or above all-time high precipitation records. Numerous communities recorded over one foot of rain in this six-week period. Twelve inches of rain is two to three times the historical average.
The summer of 1997 also brought temperature quirks. The first week of July was one of the coldest July weeks in history. In contrast to the cold weather in early July, the second half of the month was warm and very humid. Numerous communities around the state broke high dew point temperature records.
Autumn and Early Winter
The early and mid-Autumn brought a pleasant mix of dry and warm weather, leading to excellent harvesting conditions. For many locations, the first frost of the Autumn did not arrive until mid-October. After a wet week in mid-October, the weather once again turned dry, but the temperature patterns that ensued brought significant change. Cold temperatures remained in place through the second half of October and throughout November. The weather changed sharply once again in December, with very warm temperatures (for the season) returning to Minnesota. This was the beginning of what was to become one of the warmest winters in Minnesota history.
mcwg@soils.umn.edu
URL:
http://climate.umn.edu/doc/journal/annual.html
Last modified: May 14, 1998
