Mississippi and Atchafalaya River Flood Briefing May 17, 2011 2pm

1. Mississippi and Atchafalaya River Flood BriefingMay 17, 20112pm National Weather Service Lower Mississippi River Forecast Center and Weather Forecast OfficeNew Orleans/Baton Rouge, Lake Charles and Jackson, MS

2. Rainfall Next 5 Days No significant rain expected in Louisiana through Sunday

3. Today’s Weather

4. Wednesday and Thursday

5. May 19 May 20 May 21 Dry weather will prevail through the weekend. A slow moving cold front will remain west of the region. Southerly winds will increase to near 15 mph on Thursday and will continue into the weekend. May 22 May 23

6. Mississippi River Crests Morganza Spillway Utilization 20% or 125,000 CFS

7. Atchafalaya River Crests Morganza Spillway Utilization 20% or 125,000 CFS

8. Mississippi River Forecast Morganza Operation – appr. 20% or 125,000 CFS Crest Height at 57.5’May 19th Crest Height at 63.0’ May 21st Crest Height at 63.5’ May 22nd Crest Height at 44.8’ May 18th Crest Height at 32.5’ May 18th Crest Height at 23.8’cresting Crest Height at 17.0’ cresting

9. Atchafalaya River Basin Morganza Operation – appr. 20% or 125,000 CFS Crest Height at 44.5’ May 20rd Crest Height at 35.0’ May 21rd Crest Height at 31.0’ May 22th Crest Height at 27.0’ May 24th Crest Height at 18.0’ May 25th Crest Height at 17.0’ May 25th Crest Height at 11.0’ 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 – 11 FT (20% of Morganza)

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 – 11 ft

12. If more water is diverted through Morganza and stage reaches 12.0 ft this would be 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 – 11 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 45.0 ft • 61.61 ft on 03/24/1997 • 60.94 ft on 05/14/1927 • 60.70 ft on 04/24/2008 Current forecast crest 64.5 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 33.5 ft 26.00 ft on 06/11/1929 25.90 ft on 04/28/1945 25.60 ft on 03/05/1932 CRESTING New Orleans 21.27 ft on 04/25/1922 21.02 ft on 05/11/1912 21.00 ft on 04/25/1927 CRESTING