Forecast Discussion - March 21, 2023 - Multi-Day Severe Threat Coming This Week

For educational purposes only. If you live in the affected areas, please stay tuned to your local National Weather Service office for the most accurate and up-to-date information.

March 21, 2023: Our active pattern continues as a multi-day severe weather event is on tap beginning Wednesday night and focusing on Thursday/Friday from the southern Plains to the Southeast. Wednesday will feature mostly elevated storms with a hail threat across the Midwest before the more robust portion of the event begins Thursday afternoon from Oklahoma into west-central Texas. Supercells will form along a dryline with a (very) large hail and damaging wind threat before congealing into a line that will move across Oklahoma/Texas overnight. The tornado threat will likely increase Friday from east Texas into the Southeast, as low-level shear will be much stronger. We'll have to watch for a tornado and damaging wind threat with storms both along the advancing cold front and in the open warm sector.

In this video, we'll take a look at the current state of the atmosphere before comparing/contrasting model data for each day of the upcoming event. Model discrepancy remains high, especially for Friday, so we'll be able to refine the individual threats and locations over the next couple days.

Chapters
0:00 Introduction
2:07 Current observations
7:30 Model analysis (NAM, GFS, ECMWF)
37:04 Quick look at early next week's severe potential
37:38 Summary

[Duck_]

With March being so active I can imagine what April is going to be like

[aliashurricane]

I noticed that as well on the radar this afternoon and commented that it looks like a hurricane off the coast of California and even showed my mom because I happened to be sitting with her when I opened my Radar Omega. An impressive low pressure system for sure.

[Max-jpdm]

I’m under the marginal risk in Indiana. Excited

[samantharexford]

Im in Houston and I just remember having severe weather since November. Wishing this area would get a break lol

[zacharysmith]

Great video as usual! Looking forward to the day one is in Illinois!

[peachxtaehyung]

I always appreciate that you usually give your opinion on what could happen in DFW area and not JUST the state when we are in the risk area or near the risk!! Thank you for doing that! It helps my storm anxiety a lot to know what's expected and stuff instead of not knowing especially if we are just close to the risk (like with this we are kinda at the edge currently)

[runt]

Great stuff, Trey! I remember seeing this trough a few days ago and wondering how long of a pattern it'd bring because the GFS was showing it moving very slowly. Well now it's almost here and that's still holding up, and there seems to be agreement on a fairly negative tilt on Friday which I think is contributing to that low-level jet really picking up.

Unlike the recent systems, as you pointed out, moisture return is absolutely not in question. It's been a pretty constant mist/drizzle here in Central Texas the past couple days, that juicy airmass is already entrenched. The interesting aspect of this to me, however, is that we may run into a very similar situation as our most recent storm where there's going to be CONSTANT cloud cover throughout the risk areas that is only expected to cap off early on in the system's lifecycle as the EML advects into place. Thursday seems to be fairly slam dunk, even this far out, for massive hail potential from whatever supercells CAN break through.

Friday, on the other hand, is looking much more concerning. For one, that's a pretty massive model discrepancy between the three.. That said, the 18z NAM, just glancing around at CAPE and 0-3km SRH values, is really ramping up a bit west of the current SPC outlook, right in South-Central Arkansas into northern LA, with MLCAPE values over 1500 and SRH values as high as 450. And the shear vectors across that region are very perpendicular to the advancing frontal boundary, albeit right now 4 days out no pre-frontal convergence boundaries are popping up in the area. I don't know that CAPE values are going to end up being bit enough if the cloud cover doesn't break up, but if it does, there's tons of shear to work with and I bet you Southeastern Arkansas is on the docket for some nadoes if the models hold up.

The massive cold blast from the crazy polar vortex nonsense is really tempering the start of tornado season as there's just not been much of a chance for the EML to really start building up and start pressure cooking the south yet. But man, the jet stream keeps being wavy, and it seems like this year "the weather" has chosen Thursday as our "Day of Storms" as GFS is currently showing that next trough that you alluded to blasting into the south-central plains next Thursday.

Looking forward to seeing how this storm system progresses. It's a bit of a weird one and thank you for breaking it down yet again!

[peachxtaehyung]

5:50 yeah I saw that James spann tweeted a radar loop of that storm near LA and it looks a lot like it's a hurricane! So crazy

[MightyMuffins]

Definitely will be interesting how the Thursday and Friday event plays out. The hail on Thursday could be impressive as hell and those middle Texas setups usually can be so impressive on the hail sizes as we saw a week ago. As for Friday, this is trending to be very curious to me as the tornado threat is kind of trending up and up. I REALLY want to see just how many discrete cells will be able to stay ahead of the front as it come in. LLJ is gonna be impressive as hell for this Friday event so anything that gets going will be something to watch. Hell even when this does eventually line out the LLJ is for sure gonna spawn tornadoes on that line. GFS really going quite impressive on the 850s especially.

And yeah, this looks like we are about to fully ramp up into Spring and the severe season quite fast. Tornado season officially open in the Southeast....even more than it's been so far this year obviously.

[Duck_]

I don't think moisture will be a concern all season. It doesn't look like the gulf clears out after this system at the end of the week and moisture will be plentiful into Saturday also

[TheStormChasingGuy]

Looks interesting thursday thinking about friday chasing wise. Might target Snyder to San Angelo, Brady area for monster hailers Thursday evening

[StormChaserGabe]

My state is completely engulfed in the 15% for day 6

[sagemaster]

Hi. Trey, I know you touched on it a little bit. But can you explain a little more in depth that, why, if the 850 mb trough stalls and kind of hangs around near Colorado, that that would and could slow down or impede a surface low from forming, or strengthening?

[MetallicAAlabamA]

Yeah that cuts across northwest Alabama on friday, infringing on my territory lol. We've been pretty quiet so far, but this one may not be that quiet as it progresses. Tbh I'm kinda ready to see some storms. I love taking photos and I've got quite a few lightning pics that I got lucky capturing with my Samsung galaxy phone back a few years ago, and they actually turned out pretty good. And when you mentioned the wx prn comment about that system off the California coast, I was going to make a joke but I decided to stay away from that. Especially with this being a family friendly level of a channel.😬