There are many websites that are providing regular updates on the Missouri River flooding. Some of those sites are:
U. S. Army Corps of Engineers Omaha: http://www.nwo.usace.army.mil/
Douglas County: http://www.douglascounty-ne.gov/dcema/missouri-river-flood-2011
City of Council Bluffs: http://www.councilbluffs-ia.gov/
The Heartland Chapter of the American Red Cross provides emergency preparedness tips, information on shelters and much more. You can find their website at http://www.redcrossomaha.org/index.asp?IDCapitulo=V4N8M8Z9T9.