River Flooding in Louisiana

About 10 PM Eastern Daylight time, Ida had been downgraded to a Category 2 hurricane, but it was moving very slowly, at less than 10 MPH, over the region north and west of New Orleans, and north and east of Baton Rouge. This means that the rainfall was bad, and rivers in the area are expected to hit major flood levels. The good news is that the rain has mostly moved out of Louisiana and into Mississippi, Alabama and parts north, which isn't good for those areas (flash flooding is expected in some of those places), but the storm now "only" has tropical storm force winds. Also, with drier weather, New Orleans and Louisiana can begin to assess the damage they have to deal with, which is a great deal.

But the impacts are not over. River flooding - major flooding - is happening now, and it will continue to get worse. The rivers in the area won't crest until Tuesday or even Wednesday, as the water from the rain moves south. The rivers that are expected to flood are mostly north and northeast of Lake Pontchartrain, stretching over into southern Mississippi. That is the area that was exposed to the NE quadrant of the storm, and experienced the heaviest rainfall.

Unfortunately I can't find a news article on the river forecasts. A couple of the TV stations put together graphics, but they (so far) haven't published them separately from their live-broadcast. So I can only link to the source data from NOAA. Here is that link to the Lower Mississippi River Forecast Center. Every dot on the map is a river gauge. (A different map shows the entire country.) The red (moderate flooding) and the purple (major flooding) predictions are made based on rainfall to date, and expected rainfall over the next 24 hours.

The image below is typical of the data and forecast from one of the river gauges you will find at that link. The gauge is on the Tchefuncte River near Covington, LA, just north of Lake Pontchartrain. It is currently in "moderate" flood stage, being 25.5 feet above normal levels. It is projected to pass 28 feet, and hit major flood level later today and crest at 30 feet sometime on Tuesday. When I look around the rivers near me, and think, "What would it be like if the water was 25 feet higher than normal," I am surprised that it is considered "moderate" anything. (Wondering how to pronounce Tchefuncte? See this link.)