By Joe D'Aleo
Monday, June 16, 2008
From May through September of 1993, major and/or record flooding occurred across North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa, Missouri, Wisconsin, and Illinois. Fifty flood deaths occurred, and damages approached $15 billion.
The magnitude and severity of this flood event was simply over-whelming, and it ranks as one of the greatest natural disasters ever to hit the United States. Approximately 600 river forecast points in the Midwestern United States were above flood stage at the same time. Hundreds of levees failed along the Mississippi and Missouri Rivers. Nearly 150 major rivers and tributaries were affected. It was certainly the largest and most significant flood event ever to occur in the United States.
Area Impacted by the 1993 Midwest FloodTransportation was severely impacted. Barge traffic on the Missouri and Mississippi Rivers was stopped for nearly 2 months. Bridges were out or not accessible on the Mississippi River from Davenport, Iowa, downstream to St. Louis, Missouri. On the Missouri River, bridges were out from Kansas City, downstream to St. Charles, Missouri. Numerous interstate highways and other roads were closed. Ten commercial airports were flooded. All railroad traffic in the Midwest was halted. Numerous sewage treatment and water treatment plants were destroyed (Larson, 1993).
DownTown, Grafton, Illinois
The Great Flood of 1993 had been set by June 1 with saturated soils and streams filled to capacity across the Upper Midwest. Runoff from the ensuing persistent heavy rains of June, July, and August had no place to go other than into the streams and river channels. Record summer rainfalls with amounts achieving 75- to 300-year frequencies thus produced record flooding on the two major rivers, equaling or exceeding flood recurrence intervals of 100 years along major portions of the upper Mississippi and lower Missouri Rivers.
1/3 of the way through the 6 equivalent month period, there are similarities in area and amounts (1/3 of the 1993 amounts).
The upper level pattern in 1993 was characterized by blocking in the polar regions across to off Alaska and a cold closed low over Canada nosing into the North Central
There are similarities in the April May composites although the cold trough south of the Aleutians is weaker.
The first week of June was very wet with monthly anomalies exceeding 8 inches in spots. An additional 5 to 10 inches has fallen in the second week causing flooding that in many areas is exceeding that of 1993. Levees have been breached in Cedar Rapids and Des Moines in Iowa.
The Soil Moisture based July forecast is for a wet July and cool temperatures in the central.
Though there will be a much needed break this week, more storms will move across the region as thunderstorm complexes by week 2. Recall, wet springs lead to continued wet summers.
This historic flooding will lead to real issues with the crops with a big drop in corn yields from last year. This will make it impossible for the ethanol producers to produce enough to meet federal mandates and will lead corn prices already at record levels even higher. Since corn is used for animal feed and in many other food products, this will affect most of the food we buy.
Commodity traders are also concerned about possible delays in deliveries caused by flooding on the Mississippi. One lock and dam was closed on the Upper Mississippi this morning with more closures scheduled to follow due to flooding, much as we saw in 1993.
Although some are quick to blame global warming, both 1993 and 2008 were characterized by rapid global cooling with centers in Canada and the northern tier states. In 1993 it was the follow-up to Pinatubo. This year the result of a cooling Pacific and La Nina. Cooling and the enhanced contrast with normal summer warm and humid air masses across the south is what produces heavy rains and the severe weather. Rapid warm-ups as we saw in the 1930s and 1980 produce drought and heat waves.