The Lower Mississippi River Flood of 2011

1. The Lower Mississippi River Flood of 2011 Charles Gant, Dr. Gene Rench, Rich Okulski, Jeff Graschel National Weather Service Forecast Office in Memphis, Tennessee Lower Mississippi River Forecast Center in Slidell, Louisiana

2. Outline • Introduction - A brief overview of the flood and a few stats. • Mississippi River Flood History- Discussion about past flooding, levee and floodway systems, and historical crests at Memphis. • Winter/Spring 2011 - Weather events leading up to and during the flood. • The Flood of 2011 – Timeline of events, and flooding impacts across the Mid-South.

3. Introduction Total Rainfall Accumulation thru April 29, 2011.

4. Introduction Cont’d • Continuing La Nina pattern from the previous winter contributed to a series of storm systems that pushed across the central United States starting in mid-April. • These storms systems, combined with winter snowmelt across the upper Mississippi River basin, were a unified force that resulted in record flooding. • Two of five gages in the NWS Memphis service area hit record levels, Tiptonville, Tennessee and Caruthersville, Missouri. • The official crest at Memphis was 48.03ft, which was just shy of the 48.70ft record set in 1937. • There were a total of three river flooding related fatalities across the NWS Memphis coverage area during this flooding event. Damage estimates for the entire Mississippi River Valley region were around 2-4 Billion dollars.

5. Mississippi River Flood History • Flooding history along the Mississippi River in the Mid-South region was marked by two historic flooding events, the Great Floods of 1927 and 1937. • In 1882 the U.S. Army Corps of Engineers (USACE) in conjunction with the Mississippi River Commission, took on the task of extending the levee system southward from Cairo, Illinois to the Mississippi Delta in Louisiana. • With the flood control acts of 1917, and 1928 in response to the “Great Mississippi Flood of 1927”, Congress authorized the construction of floodways to aid in the control of flooding, one of which was the “Birds Point” floodway located in Southeast Missouri.

6. Mississippi River Flood History Cont’d

7. Winter/Spring 2011 • Persistent La Nina pattern was responsible for a wetter than normal winter and spring across the central United States. • Snowpack - 12 inches in Iowa, 25 inches in Minnesota, and 20 inches in Wisconsin. • The month of March produced widespread heavy rainfall across the Upper Mississippi River basin, and the Ohio River basin, with some areas seeing local rainfall totals of up to 10 inches.

8. Winter/Spring 2011 Cont’d • By the end of the month of March, many points along the Mississippi River were already in flood stage. Dyer county in Northwest Tennessee

9. Winter/Spring 2011 Cont’d • A series of strong upper level troughs would sweep across the country from mid to late April providing additional heavy rainfall on the order of 5-10 inches, and severe weather. • On April 20th, the Lower Mississippi River Forecast Center (LMRFC) issued a tentative 5 day forecast indicating river levels upwards of 57.00ft at Cairo. This crest would later be revised and upgraded to 63.00ft.

10. Winter/Spring 2011 Cont’d • This level would threaten the levee system protecting the city. Therefore, the decision was made to activate the Birds Point/New Madrid Floodway.

11. The Flood of 2011 • By early May, the river had already crested in portions of Southern Missouri. • Evacuations were already taking place in towns along the river in Lake, Lauderdale, and Dyer counties in West Tennessee. • Further downstream, officials were preparing for the worst, in and around the Memphis Area. • Continuing southward into Mississippi, officials at the popular Tunica Casinos were faced with the decision to close their doors and evacuate, which they did for the first time ever. As the crest of the river continued

12. The Flood of 2011 Cont’d Dyer and Lauderdale counties in Northwest Tennessee (May 2011)

13. The Flood of 2011 Cont’d • As the crest of the river continued to move southward into Northwest Tennessee and the Missouri Bootheel, all-time records were being set at Tiptonville, Tennessee (48.35ft), and at Caruthersville, Missouri (47.61ft). • Tributary rivers were also exceeding their banks and flooding local towns and farmland. • The city of Dyersburg in Northwest Tennessee experienced the worst urban flooding as some 600 homes and businesses were inundated by the North Fork of the Forked Deer River.

14. The Flood of 2011 Cont’d • When the crest reached Memphis, national media centered on the city in response to the flood. • As waters kept rising, the local USACE river gage along with a few others malfunctioned, and a backup gage had to be implemented immediately. • As a precaution, the NWS Memphis requested that the local old Beale Street Staff gage be read and reported to the office on an hourly basis.

15. The Flood of 2011 Cont’d • The river officially crested at Memphis on May 10th, 2011 at 48.03ft. Beale Street Staff Gage (left), Mud Island in Memphis (right)

16. The Flood of 2011 Cont’d As the crest continued downstream, flood waters ate away at the shoreline at Presidents Island, and eventually flooded the evacuated casinos in Tunica, Mississippi.

17. The Flood of 2011 Cont’d • Two weeks after the crest at Memphis, the river finally fell below flood stage of 34.00ft. • The NWS Memphis forecast office was in constant contact with the Tennessee, Mississippi, Arkansas, and Missouri Emergency Management Agencies, the USACE, as well as local officials along the Mississippi River and all tributaries in the NWS Memphis hydrologic service area. Daily conference calls and briefings were also conducted. • There was a direct line of communication between the USACE engineers on the ground at the levees, and the NWS hydrologic team, which allowed for quick response to any levee failures. • The Mississippi River at Memphis was above minor flood stage for a total of 30 days, moderate flood stage for 21 days, and major flood stage for 8 days.

18. References Duke, Christopher. 2011. 2011 Flood Post Storm Evaluation Team Timeline. Advanced Hydrologic Prediction Service: Memphis , 2011: Available online: http://water.weather.gov/ahps2/index.php?wfo=meg

19. Questions?