Big bad Barry could surprise New Orleans
Tropical Storm Barry, which may become Hurricane Barry, is on its way to the Louisiana coast. It could become a hurricane before it makes landfall. Some points I would like to make follow, and quotes from me may also appear in our official forecast story.
First, if Barry floods New Orleans, it will be from excessive rain, as it did yesterday, or from the Mississippi River. This is not what happened during Hurricane Katrina in 2005 when Lake Ponchartrain's levees broke. Those levees failed due to an immense storm surge, which Barry will not have. What Barry will have, however, is a small storm surge on top of an already-high Mississippi River at the New Orleans levees. If you look at the graph of the Mississippi River at New Orleans during Katrina in 2005, you will see that it rose from 2 feet to about 16 feet.
Today (and in fact for most of this year) it's been extremely high, around the same level that it rose to during Katrina!
Specifically, the record this year has been 16.78 feet on June 19th. The only time it has been higher than that in the modern era (after 1983) was in 2011 when it rose to 17.38 feet. That was the year the "new" levees were completed, although I'm not sure which came first. The river at New Orleans hasn't been around or over 19 feet since 1950, so, I would argue, these new levees have not been "tested." We all hope that they will hold, and the time and money that civil engineers put into them should guarantee that, but nature can surprise us. The current forecast from the NWS AHPS system is for a peak of 20 feet.
The NWS Advanced Hydologic Prediction Service shows the Mississippi River at New Orleans is expected to crest at 20 feet on Saturday, July 13. (NWS)
The second point I wanted to make is that hurricanes in the Gulf in July are fairly rare. As far as I can tell, there have been only 4 hurricanes that formed in the Gulf in July and hit the U.S. after 1950, the most recent being Danny 1997. Or, three if you don't count Chantal because she didn't become a hurricane until 00:00Z on August 1, 1989.
(Cindy 2005 doesn't count because it didn't form in the Gulf and Bob 1985 doesn't count because it wasn't a hurricane in the Gulf).
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