We have been preparing for this under what we called Hurricane Pam exercise. The slosh models linked here illustrate what will happen to storm surge hitting New Orleans from a Cat 3 storm.
slosh model When I left work about an hour ago there were 30,000 people using the Superdome as a shelter. It is estimated that once the water enters the bowl of New Orleans, it will be a long time to get it out due to pumping stations being down.
Estimates are for the eye to hit N.O. at 0700 tomorrow morning with sustained winds of at least 134mph.
This storm is not following the same path as Pam, but the surge was higher than the estimated Pam surge.
Oh...here are some cams of N.O....WARNING, I blocked cookies...
New Orleans Cams Here are cams of the traffic in Baton Rouge.
Baton Rouge Evac Cams