As a system passes through the region, it will open the door for showers, storms and the potential for severe weather. Come to think of it, I say this in almost every post. But this is not an “every post” kind of system.
This one looks pretty potent.
A Moderate Risk is in place for parts of Louisiana, Arkansas, Mississippi and Alabama. That is a “4” on the 1-to-5 scale, where “5” is the highest risk for severe weather.
But the threat doesn’t stop there.
You can see that this system will have the potential to produce severe weather from Texas to Virginia and Illinois to Florida.
What we know
— As this next system moves out across parts of Texas all of the necessary ingredients will be there for the production of significant severe weather. You can almost think of it as you build a nerautfiully-stacked and arranged soon-to-be campfire – it has the torn up newspaper in the right spots, plenty of space for air to get in, and the wood is dried and stacked with plenty of surface area – and now you’re just waiting for your uncle to show up with the lighter.
You can see that in the SigTor data. This metric is, in essence, looking at the atmospheric potential for significant severe weather.
Those are some pretty bright colors and some decently high numbers. But it is just a “potential” map, not a “gunna happen” map. And getting back to the analogy, since we are still waiting for the lighter, we don’t know for sure that this “campfire” is going to be that “great.”
What we are really pretty sure about
— Because of that, we are pretty sure (like really pretty sure) there will be severe weather across parts of Louisiana, Mississippi, and Alabama. But we don’t know specifically where, yet. Sure, we are rather confident that it will occur. vut we can’t nail down specifics yet.
— We are also confident that more than one thunderstorm will have the potential to produce significant severe weather. There are days when there is a risk for severe weather, and we say, “only one or two storms will have the potential to produce significant severe weather.”
This is not one of those days. This is the type of day where nearly every blip on the radar will need to be watched closely for the eventual development of significant severe weather.
Things we are still nailing down, but have a pretty good feeling about
— The storm mode is going to be pretty messy. It looks like there will be clusters of storms, perhaps even a broken line, and a embedded supercells. But this isn’t looking – given the data – like an April 27, 2011 day where every storm is a supercell and producing a big tornado. Some storms will only be producing wind, others hail, and some, tornadoes.
— The timeline seems to be Sunday, across the entire Gulf Coast region we usually talk about (Louisiana, Mississippi and Alabama), between about 6am Sunday and 2am Monday. That is from western Louisiana all the way through Lower Alabama.
Louisiana: Early morning through mid afternoon
Mississippi Late morning through late evening
Alabama: Mid day through overnight hours
The specific timeline is still being hammered out. But check with your local National Weather Service for specifics as they will have the super-local information you’ll want. Plus they are the ones issuing the Watches and Warnings that you’ll want to pay attention to on Sunday.
— It also looks like there will be a chance for strong tornadoes. This definitely falls under the category of “we aren’t fully sure yet, but have a feeling.”
And you know me, I hate forecasting off of feeling. So let me phrase that a bit differently.
Based on history and past events, similar past events have produced strong tornadoes. And there is no evidence currently available to suggest that this event will be different enough to lower the strong tornado threat.
The CIPS Analogs, for example show the threat for severe weather across the area as high as 60-percent. It also shows a 15- to 30-percent chance for a tornado.
The older-version, and deterministic, CIPS Analogs also show that during the Top 15 most similar setups a long-track tornado occurred on as many as six of those 15 events in Mississippi.
Thing we don’t know yet, but will begin to understand in the next 24 hours
— During the next 24 hours we will begin to learn where, specifically, storms will be more likely to produce a tornado or not. The Updraft Helicity Streaks will start to become available during the next 24 hours and that will start to give us an idea about where some of the strongest storms may occur.
— We will also start to get a better idea about / if / when / where / how much any secondary pushes of warm, moist air will occur. This will help us get a better idea of the severe threat.
Things that may save the area from any severe weather
There isn’t much out there to squash the entire severe weather threat. But there is some data out there that suggests the tornado threat – for the Gulf Coast – may be limited a bit. Without getting into the weeds too deeply there are two parameters that I watch closely for tornadoes and that is the “ML LCL Height” and the “Downdraft CAPE.”
In this case, both of those numbers are currently “out of range” when using historically-based numbers to predict tornadoes. Those numbers can be overcome by other numbers. Again, not trying to get into the weeds too deeply. But Magnitude matters with this stuff, and we don’t have enough data right now to support saying, “tornado threat is lower” based on those two above-mentioned numbers. Because there is an overwhelming amount of data pointing the other direction.
The Bottom Line
Keep up with the forecast for Sunday. Have your NOAA Weather Radio programmed with batteries. Have a severe weather plan. Know what you would do if a WArning was issued for your area.
And try, and I know these words may sound hollow, but I mean them, try to not let this stress you out too much. I know there is a lot happening in the world right now. And I know, for some, this can feel like, “ANOTHER THING?!?” but I promise we will all get through this, too. Just like with COVID, if we are prepared, do all of the right things, and act appropriately when the time is right, we will get through this, too.
