Some good news to pass along this morning: The severe threat we have been monitoring for the past week, regarding this next Monday through Wednesday, is looking like more of a low-end threat based on the data collected this morning.
I’ll say “Thank Goodness!” but I’ll also say, “Things can change, though.”
For the past week – roughly – we have been monitoring the next system that is set to move through the area. The model data has been a bit ‘all over the road’ with storm track. And because of that, models have also struggled with severe risk and storm intensity. Recall originally the model data showed it moving through the Gulf, and I mentioned that “meteorologically speaking” that wasn’t a very likely scenario given the time of year.
Generally in the Spring, the storm track starts to move further north and the “Gulf Lows” become less frequent. Until summer. But that is a different kind of “Gulf Low” I suppose.
I digress.
Now that we are getting a bit closer, the models that once disagreed are now coming into better agreement. Plus the shorter-range data is echoing that agreement, too. The agreement? A more northerly storm track. That means, as meteorologists, the model data is lining up with what is more “meteorologically accurate” for the outcome of the data.
All good things.
Now that the model data is starting to reflect something a little more believable, we get to a palce where we can start to really dissect the data.
Time to get nerdy
Next Tuesday is now within range of the NAM computer weather model. The NAM tends to run a bit “hot” many times. That means it is more likely to over-predict the threat for severe weather than under-predict it. Not always. But most times. This time, the NAM shows the next system as pushing through the area with showers and storms, with a threat for a few severe storms, too. The timeline here is between Monday at 11pm and Tuesday at 4pm. A wide window for now, but you guys know that is always how it starts.
But here is the interesting thing.
While up at 500mb, about 20,000ft, the model develops an enclosed area of low pressure that passes by to the north, in the lower levels, specifically below 850mb, about 4,000ft, there is still a lot of disorganization. Wind fields are not strong and well-defined, the return flow from the Gulf takes a bit to get set up, and the low-level jet is almost non-existent.
That is not a common occurrence in these types of setups. But it is echoed by the GFS computer weather model, too.
It leads to a very, very low-end threat for severe weather. Where most storms would have rain and wind, the tornado threat would be very, very low, and there would be almost zero hail.
The model that disagrees is the ECMWF computer weather model. It suggests more organization in the lower levels and a stronger wind field. It also shows a stronger jet streak passing through the trough at about 300mb, up around 30,000ft, aiding in pulling more Gulf of Mexico air into the area.
But even then, I will say, that it supports storms, a handful that are severe, with rain and wind, some small hail and a ‘you can’t rule it out’ chance for a tornado. That is why I say that the current model data shows a chance for severe weather, but it is a low-end chance.
Timing, in this case, is likely the thing that is saving the area from a higher risk. With storms moving through during the early morning hours, and now well-defined low-level jet, there isn’t as much energy for the storms to use.
That may change further down the road in Alabama and Georgia. The CIPS Analogs picks up on that. Highlighting area east of South Mississippi as the area of highest concern.
The Timeline
I’m going to have to stick with the NAM / ECMWF blend for timing. I think a wider window of 11pm Monday night through 4pm Tuesday afternoon is wider than what the actual window will be, but there is still enough variability within the data to keep me from whittling it down any further.
My hunch is eventually we will be able to trim it back to early Tuesday morning through late Tuesday morning. But you can science on a hunch. You need data and evidence. And right now, I don’t have either to support my hunch.
Things that are a bit suspect
Historically speaking, the area doesn’t often get storms systems to glide by at this trajectory with little-to-no consequence. Historically speaking when a system like this develops and passes through, it creates some sort of severe weather. Current model trends don’t support that. And that is great.
But it is suspect.
The one thing I teach in my classes is that “All the rules always apply, except when they don’t.” That line was taught to me by a great broadcaster and former professor, John Nicholson.
And, based on the available data, it may end up applying here. Sure, the area usually gets severe weather when systems like this pass through the area like this. But not always. This may be the exception to the rule.
We will have to wait and see. There still isn’t enough data to accurately predict a specific outcome like that yet.
Bottom Line
Right now, it looks like a line of storms will pass through the area between Monday night at 11pm and Tuesday around 4pm. That window will shrink in the coming days as we continue to learn more and get a better handle on the data (plus more will come in, too!). The main concern with the line of storms will be rain and wind. Hail looks to be on the lower end of the threats. And while we can’t rule out a tornado at this point, this doesn’t appear like a “big” tornado day for south Mississippi.
That said, with respect to the tornado threat, and not to freak everyone out…. But the December 16th severe event looked pretty “low end” up until about 72 hours out. That’s not to say this is looking like that day. It isn’t. But that was a day that ramped up in potential intensity quickly. So please don’t take this forecast to the bank. As always, these are constantly evolving situations that require all of us to “check in” once a day to see if things have changed.
