Disaster looms as parts of the south could get 20" of rain

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A new tropical system that’s likely to strengthen into the weekend could spell disaster for New Orleans and parts of the south. But it’s not likely to be from any sort of wind, but from very heavy rain and storm surge as this system will be slow to move on shore.

This storm system is likely to gather organization and strength as it heads inland the next few days, but is barely moving and isn’t likely to pick up speed anytime soon. This will likely lead to tremendous rains for some areas as the Gulf of Mexico is poised to fill this storm with copious amounts of water. Water temperatures this time of year are already very warm, typically in the mid to upper 80s… but much of the Gulf and Caribbean are anywhere from 1-3 degrees Celsius above average.

That puts water temperatures in much of the Gulf anywhere from 87°- 92°F! That’s A LOT of very warm water, which is what tropical systems “feed” on. That warm water turns into an abundance of water vapor, which then is rung out as it comes on shore as heavy rain.  Combine that with a slow moving system, and you could have 2 or 3 days with heavy rain that could top 20 inches in spots!

What could make this whole scenario worse is the ongoing Mississippi River flooding that could send the river over its banks and even top the levees in New Orleans. This would likely inundate much of New Orleans with several feet of water. The current forecast from the National Weather Service has the Mississippi River hitting 20 feet, which is above the height for several levee locations in and around New Orleans. This would send water over the levee and into parts of the city. While this level would be very high, it would not break the record height for the river in New Orleans set in 1922 at 21.3 feet.

Because of the heavy rain and flood potential, the Weather Prediction Center (which is a branch of the National Weather Service) issued a high risk for flooding for Saturday and Saturday night for much of eastern Louisiana. While this seems a bit arbitrary, this branch of the National Weather Service has issued flash flood risk outlooks for years, and the only other times a high risk has been issued this far in advance was when hurricane Harvey was expected to stall near Houston and when slow moving Florence came ashore in the Carolinas. Both of these ended with catastrophic flooding and many casualties. In fact, 90% of flood related damage and nearly half of flood related deaths occur in a high-risk zone. So if you have plans to go to New Orleans or really any other parts of Louisiana or Mississippi in the coming days, I would seriously consider canceling.