Mississippi and Atchafalaya River Flood Briefing May 9, 2011

1. Mississippi and Atchafalaya River Flood BriefingMay 9, 2011 National Weather Service Lower Mississippi River Forecast Center and Weather Forecast OfficeNew Orleans/Baton Rouge and Jackson, MS

2. Rainfall Next 5 Days Pattern Brings Light to ModerateRainto Ohio and Mississippi River Basins

3. May 11 May 12 May 13 Extended Forecast May 14 May 15

4. Mississippi River Crests With and Without Morganza Operation * Levee Heights provided by U.S. Army Corps of Engineers

5. Atchafalaya River Crests With and Without Morganza Operation * Levee Heights provided by U.S. Army Corps of Engineers

6. Mississippi River Forecast Assumes NO Morganza Operation Crest Height at 57.5’ May 19th Crest Height at 64.0’ May 21st Crest Height at 65.5’ May 22nd Crest Height at 47.5’ May 22nd Crest Height at 36.0’ May 22nd Crest Height at 28.0’ May 23rd Crest Height at 19.5’ May 23rd

7. Mississippi River Forecast Assumes Morganza Operation Crest Height at 57’ May 20th Crest Height at 62.5’ May 22rd Crest Height at 63.5’ to 64.5’ May 23rd Crest Height at 45.5’ to 46.5’ May 23rd Crest Height at 35.0’ May 23rd Crest Height at 25.0’ May 24th Crest Height at 17.0’ May 24th

8. Atchafalaya River Basin Assumes No Morganza Operation Crest Height at 50.0’ May 23rd Crest Height at 40.0’ May 23rd Crest Height at 35.0’ May 24th Crest Height at 25.0’ May 24th Crest Height at 14.0’ May 25th Crest Height at 14.5’ May 25th Crest Height at 9.5’ May 25th

9. Atchafalaya River Basin Assumes Morganza Operation Crest Height at 50.0’ May 23rd Crest Height at 40.0’ May 23rd Crest Height at 35.0’ May 24th Crest Height at 27.0’ May 24th Crest Height at 21.5’ May 25th Crest Height at 19.0’ May 25th Crest Height at 12-13’ May 25th

10. DATE CREST 05/28/1973 10.53 RECORD 06/27/1957 8.46 04/05/1997 8.06 04/18/1975 7.95 06/06/1983 7.32 MORGAN CITY IMPACTSFORECAST CREST (NO Morganza)– 9.5 FTFORECAST CREST (Morganza) – 12 to 13 FT

11. 4 ft – Water will move up the bank and across access roads below the city dock. Vessel Traffic safety rules will be strictly enforced by the US Coast Guard. Minor 5 ft – Floodwall gates will be closed to protect against higher stages. Vessel traffic will be affected by stronger river current and vessel traffic safety rules will be strictly enforced by the U. S. Coast guard. Minor 6 ft – The city dock will be under water. Water will cover the lower end of Belleview Front street in Berwick. Vessel traffic will be affected by stronger river current and vessel traffic safety rules will be strictly enforced by the U. S. Coast guard. Minor 7 ft – Buildings at the foot of Ann street on the river side of the flood wall will flood as water overtops the Rio Oil Company dock. Buildings on the river side of the Berwick floodwall will flood. River traffic restrictions will be strictly enforced. Moderate 9 ft – structures on the river side of protection walls in Morgan City and Berwick will be under water. River traffic restrictions will be strictly enforced. Moderate MORGAN CITYFORECAST CREST – 9.5 FT

12. THERE IS A MAJOR FLOOD THREAT. BACK WATER FLOODING OF 5 TO 6 FEET AT BAYOU BOUEF WILL CAUSE DAMAGE EAST OF MORGAN CITY TO THE COMMUNITY OF AMELIA. STRUCTURES ON THE RIVER SIDE OF PROTECTION WALLS IN MORGAN CITY AND BERWICK WILL BE UNDER WATER. RIVER TRAFFIC RESTRICTIONS WILL BE STRICTLY ENFORCED. MORGAN CITYFORECAST CREST – 12 - 13 FT

13. Records on Mississippi River Red River Landing Baton Rouge 47.28 ft on 05/15/1927 45.18 ft on 05/16/1922 45.18 ft on 04/29/1945 Current forecast crest 47.5 ft • 62.30 ft on 03/25/1997 • 60.94 ft on 05/14/1927 • 60.96 ft on 04/25/2008 Current forecast crest 65.5 ft Donaldsonville Reserve 36.01 ft on 05/15/1927 34.75 ft on 05/16/1922 34.11 ft on 04/29/1945 Current forecast crest 36.0 ft 26.00 ft on 06/11/1929 25.90 ft on 04/28/1945 25.60 ft on 03/05/1932 Current forecast crest 28.0 ft New Orleans 21.27 ft on 04/25/1922 21.02 ft on 05/11/1912 21.00 ft on 04/25/1927 Current forecast crest 19.5 ft