25th Anniversary of the Great Flood of 1993

Introduction

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Source: https://water.usgs.gov/nwsum/WSP2425/flood.html

The Great Flood of 1993 resulted in $36.3 billion dollars in losses and 48 deaths.  It was considered the 8th worst natural disaster in US history in terms of dollars.  The top six were hurricanes, followed by the 1988 drought/heat wave.  Large regions of the Missouri and Upper Mississippi River basins were impacted by heavy rains from June through August of 1993. The rains were widespread with the largest totals concentrated in Iowa.

I will share some climatic factors of the event.  However, the most important thing to remember is that this was a large, slow-moving human disaster.  I had friends and family in the affected area and it was indeed tough times.  The St. Louis Post Dispatch recently did a story on the 25th Anniversary, showing the extent of the disaster.

In the end, I will try to answer the question – can it happen again?

Climate Factors

From the study by Kunkel, Changnon, and Angel (1994), other features of the 1993 Flood that made it so severe include:

  • above-normal soil moisture at the beginning of June 1993
  • large-sized areas of moderate to heavy rains
  • the occurrence of rain areas orientated along the main stems of major rivers
  • a large number of localized extreme daily rainfall total greater than 6 inches
  • below-normal evaporation due to cooler temperatures and increased cloudiness

Several reports came out of the Flood of 1993, including this Water Survey report, this book by Stan Changnon, and this Federal report.

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July Slightly Cooler, Drier than Normal

Temperatures: Based on preliminary data, the statewide average temperature was 75.1 degrees, just 0.3 degrees below normal.  Temperatures reached into the upper 90s at several locations in the first half of the month.  One of the warmest readings was 99 degrees at Flora on July 5. A few stations dropped down into the upper 40s at night.  Four locations reported a low of 48 degrees: Mt. Carroll on July 7, Stockton on July 13, Shabbona on July 28, and Avon on July 31.

Here are the day to day temperature departures from normal for Champaign IL and reflect the changes experienced across much of the state.  The hot weather of May and June continued in the first week of July but quickly cooled by July 6.  This was followed by alternating periods of cooler and warmer weather until July 18 when temperatures remained at or below normal.

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Rainfall:  The statewide average rainfall was 3.41 inches, 0.67 inches below normal.  A few areas experienced above-normal rainfall, especially between Interstates 70 and 72. Much of the rest of the state was down by 1 to 2 inches.  The largest monthly total for July was 8.28 inches at Beecher IL (IL-WL-84).  Several stations reported less than an inch of rain for the month, including northern Cook and Lake counties.  The lowest monthly total for July with complete data was 0.59 inches at Park Ridge (IL-CK-180). Continue reading

The Outlook for August and Beyond

First of all, is it really July 19th already?  As a kid I remember summers lasting almost forever, now it seems to last about two weeks.  I feel cheated.

July: So far, the statewide average temperature for July is 77.4 degrees, 1.5 degrees above normal.  The statewide average precipitation is 1.94 inches, 93 percent of normal.  Strangely, the interior of the state is experiencing near to above-normal precipitation while the edges have experienced below-normal precipitation (map below).

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NWS Outlooks: The NWS has released their outlooks for August and beyond.  The big news is the possible return of El Niño. While conditions are currently neutral in the Pacific Ocean, the chance for El Niño increases to about 65 percent in the fall, and to about 70 percent during this winter. As a rule of thumb, warmer than normal temperatures are expected in winter during strong El Niño events. Continue reading

Warm, Wet June for Illinois

Summary: According to preliminary data, Illinois experienced its 11th warmest and 14th wettest June on record. The statewide average temperature was 75.0 degrees, 3.1 degrees above normal. The statewide average precipitation was 6.36 inches, 2.15 inches above normal.

Precipitation: The greatest monthly total for June in Illinois was 14.58 inches at Rockford (IL-WN-8). In addition, the Rockford Airport reported 14.23 inches, their wettest June and wettest month on record. Based on radar and rain gage data, precipitation was especially heavy across northern, east-central, and southeastern Illinois with widespread amounts in the 10 to 14-inch range. Meanwhile, parts of western and southern Illinois received less than 3 inches of rain.

 

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June – Warmer and Wetter in Illinois, More to Follow

Summary: The statewide average temperature for June so far is 75.3 degrees, 4.4 degrees above normal. The statewide average precipitation for June is 3.61 inches, which is about 130% above normal. However, the precipitation is spread unevenly throughout the state. Above-normal temperatures are expected to continue for July.

Temperature: Both the average high and average low for June has been above normal (maps below). The average high ranged from the low 90s around St. Louis to the upper 80s in the southern two-thirds of Illinois. The average high ranged from the upper 70s to the low 80s in the northern third of the state. The average lows ranged from the upper 50s in northeast Illinois to the 60s for the rest of the state.

Precipitation: Precipitation was highly variable across Illinois, which is fairly typical for summer months (below). There are a few areas in pink with 10 to 15 inches. Areas in shades of orange and red have precipitation amounts of 4 to 10 inches, well above normal. The largest monthly total so far is Beecher City (Effingham County) with 11.22 inches. Meanwhile, rainfall has been less plentiful in western and southern Illinois with amounts of 2 inches or less. Continue reading

Warmest May on Record for Illinois

Temperatures: Based on preliminary data, the statewide average temperature for May in Illinois was 70.6 degrees, 7.9 degrees above normal and the warmest May on record. The old record was 69.4 degrees set back in 1962. A brief examination of daily records indicates that Springfield, Champaign, Quincy, and Carbondale all had daily mean temperatures at or above normal for each day of the month. On the other hand, Chicago, Rockford, and Peoria had a few dips into the below-normal territory but overall finished above-normal for the month. Here is the graph of daily mean temperature departures from normal for Champaign-Urbana.

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Illinois to Feel Effects of Alberto

According to the National Hurricane Center, what’s left of Subtropical Storm Alberto will reach Illinois on Wednesday, bringing widespread rain to areas that are driest in the state. By the time it reaches Illinois, it will have weakened considerably with the greatest risk from flooding instead of high winds. Here is the projected path:

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