I’m starting to get more concerned about an over-running rainfall event that would lead to some highly localized flash flooding for folks across parts of Louisiana and southern Mississippi south of Highway 98 but north of I-10/I-12.
I think everyone has a chance for some rain, heavy at times, rumbles of thunder, and the potential for some gusty wind, today. I don’t think we can rule out a tornado, either.
But my growing concern is for a stripe of land to pick up more than 6″ of rain today. given the setup.
The Setup
Think back, if you can, to March 2016. We ended up with an over-running rainfall event that dropped nearly a foot of rain across a handful of counties in the area. I think a similar – but not nearly to that magnitude – event may setup today.
I’ve highlighted the area I think has the greatest potential to see rainfall totals up around 6″ today. That area is in red. The area outside of that in green is where it is still possible, but less likely. The bullseye for the heaviest rain may shift around a bit as the rainfall starts and the different puzzle pieces get in place.
Why is this happening?
The stream of moisture off the Gulf of Mexico will continue this morning and into this afternoon. As it does so, we will see showers and storms develop along the HWY 98 corridor and points to the north.
I think this may develop a bit of a cold pool. And while the cold pool will want to move southward, it may be held up a bit, almost stationary, with the southerly flow off the Gulf pushing back against it.
And that may leave us with a bit of a boundary. You can almost think of it as a mini cold front, but it isn’t going to be moving very fast.
And that Gulf air with all of the moisture and heat will bounce off that cold pool and rise upward and make clouds. And those clouds will quickly turn to raining clouds, and storming clouds. And they will rain over the same areas over, and over, and over.
A bit like this – very artistic – graphic shows below.
The one asterisk I’ll add is that the stripe of heaviest rainfall within the model guidance is trending more northward. So my bullseye graphic above may be a bit too far south by the time the rain really gets going.
The Bottom Line
Keep an eye to the sky and another eye to the low-lying areas today. While severe weather is possible, I am more concerned about the potential for flash flooding. I think most folks see between 1″ and 3″ of rain today, but a stripe of land in Louisiana and Mississippi will see up to 6″ of rain, too.
The timeline shows the rain starts up later this morning and being off-and-on (and in some cases always on) until about 10p tonight. Then storms become a bit more hit and miss as we head into the overnight hours.
Six inches of rainfall isn’t enough to cause catastrophic flooding in most places. But it will make water pool up in low spots, water will likely be across some roads, and some streams may over-top their banks for a short period of time. And I can’t rule out, in some cases, water getting close to – or in – some homes for a short period of time, too.
If a Flash Flood Warning is issued for your location, make sure you have an easy way to get to higher ground if needed. That means knowing a route to get from where you are to a safer spot that doesn’t cross any low-lying areas or use any bridges.
If a Flash Flood Emergency is issued for your area, that needs to be treated a bit like a Tornado Warning. The main difference is instead of seeking shelter in the lowest level of your home, you need to get seek shelter in the highest point of land you can find. Often times this includes walking or driving to a new location that is away from low-lying areas and streams/creeks.
Stay safe today, I’ll monitor the radar and offer updates as needed! And as a reminder, if you are looking for a weather app to give you updates on the weather, offer a good radar, and ping you when the NWS issues alerts… try my new app! Tap on this link to grad the NickelBlock Forecast weather app! It is in Beta right now, so there may be a few bugs and kinks, still. But give is a shot and let me know what you think!
