Climate Update -- Spring
and Summer, 1997
(prepared August 15)
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 east central, and central Minnesota. Precipitation totals were less than four inches in many counties for the period. Those counties received less than 50 percent of their normal 10 inches of precipitation. In some Minnesota communities, April 1 - June 23 precipitation totals were near or below all-time low precipitation records. A precipitation ranking map shows that roughly one quarter of Minnesota was at or below the 5th percentile. A community at the 5th percentile indicates that precipitation totals for this period were this low or lower in only 5 of the last one hundred years. Cool weather mitigated the extreme dryness somewhat by reducing evaporation demand. Another alleviating factor was the wet late-Autumn of 1996. The Autumn precipitation was especially heavy in those eastern sections of the State where the 1997 Spring dryness was most intense.
The dry spell ended abruptly in the Northwest when heavy rains drenched many counties on June 22-24. A slow moving storm system passing through northern Minnesota brought intense rains to that area. Two to three inches of rain fell in portions of Clay and Becker counties during the first wave of storms. The rains resumed in earnest just hours later, dousing portions of Norman, Polk, Red Lake, Clearwater, and Beltrami counties with three to six inches of additional rain. The deluge led to flooded basements and closed roads.
Heavy rains returned to Minnesota on June 28-29 when a complex of thunderstorms brought downpours to portions of northwestern, central, and southwestern Minnesota. The storms dropped a band of five inches or more inches of rain through Kandiyohi, Meeker, and Mcleod counties.
On July 1, for the third time in roughly a week, heavy rains fell across portions of northwestern and central Minnesota. The northwestern counties of Red Lake, Pennington, Marshall, and Kittson reported rainfall amounts of one to four inches. Rainfall totals of one to four inches also stretched across central Minnesota from Lac Qui Parle and Yellow Medicine counties through the Twin Cities metropolitan area. The heavy rains fell on the already drenched soils of central Minnesota. Portions of Kandiyohi, Mcleod, and Meeker counties recorded weekly totals of over eight inches. The July 1 event was notable not only for its volume, but also its intensity. The St. Paul campus of the University of Minnesota received three inches of rain in less than one hour. The intense rainfall rate exceeded the 100-year storm total for the area. The torrent led to numerous occurrences of urban and small stream flooding as well as countless wet basements. The severe thunderstorms that brought about the intense rains also caused extensive wind damage throughout central and east central Minnesota. The high winds downed many trees and damaged numerous buildings. Hail-damaged fields, particularly in western Minnesota, became an increasingly common sight throughout late June and into July.
The first week of July was one of the coldest July weeks in State history. Temperatures averaged 10 degrees below normal. International Falls recorded a low temperature of 34 degrees F on July 7, the coldest July temperature in their history. On the same morning, the observer 3 miles south of Tower recorded a low temperature of 24 degrees F, tying the state record for the lowest July temperature. 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. Dew points in the high 70s, and even 80 degrees F were common during the second half of the month.
On July 22, heavy rains once again doused the Twin Cities. This was the third significant rainfall event in the month of July for the area. Rainfall amounts ranged from one to five inches. The deluge fell upon already saturated ground, again leading to numerous reports of urban and small stream flooding and wet basements.
Extremely heavy rains plagued southern and central Minnesota on July 24-25. The event began in the evening hours of July 24 in southwestern Minnesota and continued into the morning hours of July 25 in eastern counties. Some of the rains fell upon relatively dry areas in Minnesota's southwestern counties. However, much of the rain in central and southeastern counties fell upon already moist ground leading to the flooding of roadways and other difficulties. The heaviest reported rainfall totals were four to five inches in northern Lincoln and Lyon counties, portions of Sibley and Mcleod counties, and a portion of Goodhue county.
Yet another intense rainfall event hammered the St. Cloud area on August 2, dropping over three inches of rain in just a few hours. On August 14 and 15, a small area of Rice and Steele counties was soaked with over six inches of rain. The Medford area of Steele county received a whopping 24 hour total of 8.2 inches
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 at the 99th percentile for precipitation. The 99th percentile indicates that these locations were near or above all-time high precipitation records. Numerous communities recorded over 12 inches of rain in this six week period. Twelve inches of rain is two to three times the historical average. For many areas, the mid-Summer of 1997 will be remembered as one of the wettest periods ever.
Fed up by Mother Nature's schizophrenic behavior, University of Minnesota climatologist Mark Seeley, wrote this not-so-flattering summation of the 1997 Summer weather:
Summertime isn't always so sublime.
Sometimes it's a crime.
Wet basements. Damaged pavements. Insurance claimants.
Saturated soil. Cars that boil. Food that spoils.
Broken trees. July freeze. Plant disease.
Running fans. Watering bans. Sweaty hands.
Too much heat. Cannot sleep. Feeling cheap.
Soccer rainout. Broken downspout. Many chores to count.
Downed wires. Irritable drivers. Patience that tires.
Forecasters mistakes. Hard to take. Give 'em a break.
State Climatology Office, DNR - Division of Waters
mcwg@soils.umn.edu
URL:
http://climate.umn.edu/doc/journal/talksu97.htm
Last modified: August 27, 1997
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