And now for those tidal gauges, via NOAA Tides and Currents. By way of explanation/reminder:
• The blue line is the expected, “normal” water level, as the tides come in and out. Basically, it’s what the tides would be without Isaac.
• The red line is the actual observed water level. When you see the red line not declining, or only declining slightly, while the blue line is going way down, that’s bad news. It means the storm surge is preventing the tide from going out, so the next high tide will likely be much higher (assuming the surge is still present when the tide comes in).
• The green line is the “residual” level, i.e., the difference between the red and blue lines. Basically, the green line is the storm surge. So, for instance, if the red line is declining as the tide goes out, but not as much as it “should” be declining (as in the scenario just discussed), that will cause the green line to go up.
Now, on with the show… proceeding generally from west to east along the Gulf coast…
And here are some more charts, from the St. Charles Parish Water Level Monitoring System:
UPDATE: I’ve found some more really helpful lake and river gauges from the Army Corps of Engineers. [UPDATE #2: More great stuff here!] Some of the best ones, unfortunately, I can’t figure out how to embed, but check ‘em out:
And here are some more, mostly river-level gauges, which may become more important as the focus shifts from storm surge to inland flooding: