5/21/22 9p Update: Tomorrow may not be quite as rainy for some, but even more rainy for others across the Southern MS/AL/LA region

Today was a pretty wet day for some spots while others remain bone dry. Looking at the estimated totals from radar, places in Forrest and Perry counties in Mississippi picked up nearly 4″ of rain today while just down the road in Marion counties things were bone dry.

MRMS rainfall estimates // Courtesy: Pivotal Weather

Despite what is shown above, it does look like most of the parishes in southeastern Louisiana did pick up between 0.10″ and 0.50″ of rainfall.



Tomorrow’s rundown…

I want to start off with some blunt honesty here: This forecast is a low-confidence forecast. While I’m trying my best to nail down specifics, it is difficult to do when dealing with lingering outflow boundaries and weak fronts with developing areas of surface low-pressure.

There are just a lot of moving pieces all happening at once and each one could make or break this forecast.

Okay!

As we move into tomorrow, the atmosphere may be pretty well worked over, so we should have to wait a bit longer for storms to develop. And they will likely develop along the western edge of where all of the rain fell today.

HRRR computer weather model radar estimate for tomorrow afternoon // Courtesy: Pivotal Weather

Storms today laid down a fair bit of outflow and those boundaries are going to be the focal point for storms to erupt tomorrow. The reason it is more likely on the western edge as opposed to the northern, southern or eastern edge is related to where the boundaries will interact with the naturally lifting in the atmosphere.

700mb vertical velocity map from teh NAM comptuer weather model // Courtesy: Pivotal Weather

The blobs of lighter blue are places where model guidance thinks the most vertical motion in the atmosphere will be most likely. Line that up with already-established outflow boundaries and you have a recipe for more storms.

Storms will feature brief heavy rain, lightning, gusty wind and maybe some more pea-sized hail, like today. That said, storms won’t pack quite as much of a punch tomorrow in the places that got punched today.

Another good piece of evidence suggesting storms are more likely west than elsewhere is a look at the skew-t data in places that are east of I-55.

HRRR computer weather model skew-t data // Courtesy: Pivotal Weather

Things are looking a bit drier than today in the chart itself, there isn’t as much forcing, the amount of instability is lower and there isn’t any shear. So, if storms do develop, they will be far less potent than storms today if this data holds true.

Compare that chart above, with what the same chart looked like today, below, and you can see the difference.

HRRR computer weather model skew-t data // Courtesy: Pivotal Weather

Still no shear, but there was much more instability, some forcing (omega) and it was slightly more moist through the column.

Then, as we head through the overnight, it looks like another round of storms may develop in places to the east and slide across the area.

NAM computer weather model radar estimate for tomorrow overnight and into Monday morning // Courtesy: Pivotal Weather

These storms would be mostly just heavy rain, lightning and some gusty wind. Nothing too terribly potent.



Timing it out

With all of that said, it looks like there will be a few windows for storms tomorrow and Monday. While there may be a few lingering storms overnight tonight, things should be mostly dry.

Tomorrow, storms develop after lunch and should end after supper for an hour or two, then ramp back up overnight and into the pre-dawn hours on Monday. Then more rain Monday around lunch before things ease off into the afternoon.

And while I have tomorrow morning with the “Thunderstorms Unlikely” showing, there is still a chance for rain. Not a “good chance” for rain, but it can’t be completely ruled out. Please keep in mind that this isn’t a high confidence forecast. There are plenty of places that I could be quite incorrect. I tried my best for you guys, but this is a tricky one tomorrow.



Author of the article:


Nick Lilja

Nick is former television meteorologist with stints in Amarillo and Hattiesburg. During his time in Hattiesburg, he was also an adjunct professor at the University of Southern Mississippi. He is a graduate of both Oregon State and Syracuse University that now calls Houston home. Now that he is retired from TV, he maintains this blog in his spare time.