Wednesday, July 10, 2019

Will "Wannabe Barry" Turn Into Another New Orleans Hurricane Calamity?

Serious flash flooding in New Orleans this morning. Is this a
prelude to an even bigger calamity from wannabe Barry?
New Orleans was badly flooded today as a storm that wants to become Tropical Storm Barry gathers steam in the northeastern Gulf of Mexico.

This morning's flash flood emergency in New Orleans was created by intense thunderstorms on the outer edges of that mishmash of Gulf thunderstorms that might become Barry. Up to six inches of rain fell in just three hours this morning.

Many parts of New Orleans, including the French Quarter were under water this morning. If the worst case scenarios with wannabe Barry play out, this morning's destructive flooding will look like child's play. Things have the potential to get very difficult in the Big Easy.

You might remember my post a couple days ago that mentioned a cluster of thunderstorms that had its origins in Missouri and Tennessee was drifting down to the Gulf of Mexico and had the potential for grow into a tropical storm.

That potential seems like it is being realized. The National Hurricane Center says wannabe Barry will almost certainly grow into Tropical Storm Barry by Thursday and could easily increase further into a hurricane by the weekend.

The future path and strength of wannabe Barry is wicked uncertain, but early indications are it will move west over the northern Gulf of Mexico, then turn north and make landfall somewhere west of New Orleans.

If that happens, New Orleans would get the worst of the storm surge, which is water pushed ashore by a storm.

That's bad enough for low lying New Orleans. However, under normal circumstances, a storm surge being pushed northward up the Mississippi River by the city wouldn't be that big of a deal, as a levee system would protect the area.

Hurricanes in the Gulf of Mexico usually hit later in the year, when the Mississippi River is typically pretty low. The levee system around New Orleans protects the city unless the water gets more than 20 feet deep.

So if a storm surge increases the water level in the river from, say, five feet to 10 feet, the city and its levees can handle it.

Here's the problem: Wannabe Barry is gettting going early in the season, so the Mississippi River is higher than it would be in say, September, the height of hurricane season.  Tropical storms and hurricanes in the Gulf of Mexico aren't too off the charts weird in July, but it's still a bit unusual for things to be cranking this early.

The real trouble is the Mississippi River is very, very high from all the epic rains that fell upstream in the Midwest between March and June. So the water is now at around 16 feet, which is just a little below flood stage. A storm surge from wannabe Barry could push the water up over 20 feet, which would overtop levees and potentially give us Katrina all over again.

Another levee system that kept the waters of the Gulf of Mexico out of New Orleans led to the Katrina calamity of 2005. This potential mess would be different, as the water would be from the river, not the Gulf.

Of course, this is all a big maybe at this point. Maybe the surge won't be that big. Maybe Barry won't get very strong. Maybe Barry's path will take a turn so that New Orleans need not worry about anything.

Some forecasts say the unusually high water temperatures in the Gulf of Mexico might prompt Wannabe Barry to grow much more intense than current estimates. Winds in the upper atmosphere over the northern Gulf of Mexico will also become lighter, another sign that this could get pretty big pretty fast.

On the other hand, there the winds in the upper atmosphere might be stronger than forecast, or there could be intrusions of dry air, or wannabe Barry could travel closer to land during its formative stages, all of which could hobble this storm and make it not that much of  a powerhouse.

The track of the storm, which will be key on who gets the worst of it, is still a wild card, too. Nobody is sure where this thing will go.  

Yesterday, when flood forecasts put the storm surge flood expectations at 19 feet, not 20 feet, officials were sanguine about everything. Even at 20 feet, workers can reinforce levees and close flood gates to stave off flooding.

All this means that another catastrophic flood in the New Orleans area is not a done deal. At all. But it's enough to make me and a whole bunch of other people worried.

Plus, this morning's flood was no walk in the park. There's lots of damage in and around New Orleans from today's inundation. We can all hope that this turns out to be the worst of it.

As anybody in Nebraska, or California, or Washington DC or Kansas or Oklahoma or Ontario or Quebec can tell you, we've had enough flooding disasters lately.


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