Don't worry about the federal levees around New Orleans. President Obama has this under control. He has made sure that the Federal government is prepared. The pumps are ready, the levees are repaired and emergency crews are waiting to spring into action. Republicans can party on in Tampa without worry because a Democrat is president.
Unfortunately, some small levees, controlled locally, will be overtopped. Over 100 years of disasters along the Mississippi proved that state and local control of levees was a failure. Local levees on the west side of the delta could fail today. That's what local levees do.
Federal management of the whole river system is required to protect people living along the river, especially the residents of New Orleans. Republican mismanagement of the levee system under George W Bush led to the Katrina disaster. The Bush administration was warned repeatedly but failed to act because they were ideologically opposed to federal control. Republican ideology led to the Katrina disaster. Strong, effective federal leadership is needed when a hurricane comes. We have with President Obama.
The biggest threat to life and property away from the area affected by landfall is heavy rain - up to 13 inches. Flooding triggered by heavy rains can be dangerous hundreds of miles inland. Every year people die trying to cross flooded roads. Do what the sign says:
Turn Around. Don't Drown.Isaac will produce heavy rain hundreds of miles inland. About 12 inches of rain can be expected around New Orleans over the next 24 hours.
We got lucky according to Jeff Masters, who just posted an update to his blog. Isaac was forming an inner eye wall, something he has never seen happen before. Fortunately, Isaac came ashore before a tight eye wall, with very high winds, came together. However, the atmosphere is very wet and Isaac is moving slowly so some areas will see 15 to 20 inches of rain. Flooding will be serious in low lying areas.
The storm surge is subsiding now, helped by a dropping tide. This should help in the area where waves were pushing water over the local levee.
At 11:30 am EDT, here were some of the storm surge values being recorded at NOAA tide gauges:Cherry picked rainfall totals through 11AM.
8.0' Waveland, MS
8.2' Shell Beach, LA
2.0' Pensacola, FL
4.6' Pascagoula, MS
3.4' Mobile, AL
The peak 11.06' storm surge at 1:30 am EDT this morning at Shell Beach, which is in Lake Borgne, 20 miles southeast of New Orleans, exceeded the 9.5' surge recorded there during Category 2 Hurricane Gustav of 2008. In general, the storm surge heights from Isaac have been more characteristic of a strong Category 2 hurricane, rather than the weak Category 1 hurricane one might suppose Isaac is, based on its top sustained winds of 75 - 80 mph.
rainfall totals from Isaac through 11 am EDT:
9.26" New Orleans Lakefront Airport
5.59" Belle Chasse, LA
5.21" Mobile, AL
3.65" Hattiesburg, MS
3.42" Gulfport, MS
2.81" Biloxi, MS