Moderately Unstable

It's a cycling supercell in a good environment. I'm racking my brain thinking about what's causing the cycling instead of a sustained long tracker. The winds are backed, low level SRH is quite high, no other storms to interact with. Odd. Whatever the damage track(s) is/are tomorrow, it will be interesting. There are no spotter reports on this since the Seven Oaks area, yet there have been multiple debris balls, and other signatures, in a good environment. We have learned so much about tornadogenesis and forecasting the last decade, to the point we can use debris heights, to estimate tornadic wind speeds. But I still don't know of any literature that would explain why this supercell is cycling so much and others just "stay down". Not complaining, this would be a heck of a damage path if it was all on the ground. Wonder if the storm base here is higher and it's therefore having more trouble sustaining tornadoes on the ground, even though, say, 1k feet up, we've got a fairly continuous funnel. But earlier videos didn't show a high cloud base so that kinda puts cold water, somewhat literally, on that theory. Edit: spotter report did just come in suggesting a tornado in Jasper, from a 911 call center. 5 E of Jasper. So, that may have been the start of that particular touchdown. There is another uncorroborated report of the tornado OG in Jasper, of unknown magnitude, also 911 call center. That may have been strong RFD that gave off the appearance of a tornado. Won't know until much, much later. Can you imagine what this would have been like were it actually on the ground for the whole distance?

Debris sig. Well, it does look like it hopped up over Jasper. They really lucked out, hopefully. That would have been absolutely horrific. I'm not saying the current situation is good, but, they really dodged a giant bullet. I think what occurred before, and is likely now occurring right after, Jasper, is going to speak to what exactly it was that they avoided tonight.

Yep, good call by them. Dear lord.

Yes. Jasper is in serious trouble. That couplet is nasty, and it is getting stronger with each scan, and it's heading right for them. Once someone can confirm this visually, this is one of the times an emergency warning is warranted. People need to get to shelter, now.

Well, here's the link to snapchat, as was linked above: https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYbrbdlJLTjOtAAXGkM9xgAXGkM9oXAO1OAA/@30.891044,-94.751369,9.66z. I'm looking at the damage, the atmospheric environment the tornado was going through, the height debris was lifted to (around 25k feet), a couple of the videos suggest subvorticies (which would have been the spots you'd see the EF4 damage here). SPC did note they thought the environment was supportive of EF3 intensity so I think that's relatively easy to conclude. I'm basing EF4 off of the height debris was lifted to coupled with the initial images of damage, which I strongly doubt are anything close to the WORST damage that occurred. Additional: https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYCRF0KopX8ELtAXGkMO2AAXGkMOq_AO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYTzt7Gl3gH_HsAXGkIc8qAXGkIcz4AO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYaxvwtpDASDYYAXGkLfYFAXGkLfM2AO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAY7StDf0ncdRNdAXGkJLHtAXGkJK9sAO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYey_3B0Y16OgxAXGkI8DXAXGkI75LAO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYIsa_X-XJHRbsAXGkJFjrAXGkJFaiAO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYGoiCfPtp360dAXGkJB6hAXGkJBhUAO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYCu_x8p61xnFtAXGkIrVYAXGkIrG4AO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYDSmO1clrGur0AXGkIpUxAXGkIpILAO1OAA/@30.901073,-94.817562,11.18z https://map.snapchat.com/ttp/snap/W7_EDlXWTBiXAEEniNoMPwAAYvyMS9C9pSTIqAXGkIta3AXGkItSTAO1OAA/@30.901073,-94.817562,11.18z

The TX storm is heading towards Jasper, completely pristine environment, high STPs. It appears that the previous tornado, which if you look at the damage pictures and videos coming in on snap and twitter, was at least high end EF3, and was likely an EF4. The population in Seven Oaks is only 111, but that appeared to have been a direct hit. Also, this thing is heading for Jasper. As for weakening...it appears that outflow from the storm was looped back around and the air was still unstable enough to promote precipitation development which cut off the tornadic inflow. Super classic tornado cycling. The cell remains isolated, so, if it cycles, it'll generate a new low-level circulation to the southwest. There is no lack of available energy or shear, and nothing is holding it back. It may well cycle right now but I don't think it's going away in the near future. Circulation remains quite strong. I'm cycling back and forth between KPOE and HCX. It'll likely produce again shortly.

Not relevant. As I said, public forum. If you have a problem with that, there are other places you can chat with folks. Being derogatory doesn't help anyone. First, remember that folks have different specialities. I have a degree in meteorology, and have taught classes on it. Have you? In school, you can take different tracks, and the higher you go, the more you specialize. The skills for forecasting summer severe wx are different than for winter. Also, remember--there are MANY worse ways for someone interested in 'rubbernecking' to spend time than to chat about something on a forum (see YouTube for your assortment of people driving through bad weather and oggling the carnage). At the end of the day, most people who get into meteorology, don't do so because they hate severe weather. That has nothing to do with wanting people to be hurt by weather though. No one wants people to die. But, I'll just be blunt, I didn't go into this field because I was excited by calm sunny days! Definitely, absolutely, not worth all the calculus, physics, chemistry, comp sci, technical writing, misanthropic compatriates and starting pay less than a school bus driver...etc. Sorry, if that's mean. This is the wrong place to be if you're not trying to see people be impressed by bad weather. Be kind, and be grateful people that have knowledge are willing to discuss and share it at all. 80%+ of my met friends are not on this forum. There is a good reason for that. When they're done for the day, they are DONE for the day. I always try to help people when I can, and learn when I don't know. Remember that we are all human, we are not that different, and you'll be much less angry about the world if you try approaching new people with some kindness. Cultivate empathy. Else, you'll go mad. I'd rather personally, and have others, be here, than IN those storms, hopefully you agree.

It's a public forum, not a professional forecasting office. The point is to discuss things, learn, and make mistakes. Also, websites like this operate based on ad revenue. They're expensive, and need eyes and participants. There are plenty of private weather chats you can join on social media apps. If you want only expert guidance, there are many better sources. Bring people in, educate, correct, and comment.

55k actually. It is entraining air from other storms and isn't staying discrete. As with most supercell structures, when a well defined structure like this crashes into another storm, it makes a mess. If it sorts that out, it has plenty of energy and space to produce. Couplet never really went away, but it is far from the radar. Beam height at the couplet is centered at 6.2k feet. Strong rotation, if it follows a typical sig tor tornadic supercell pattern, it will produce again. More a question of how strong, how long, and what does it do with the other cells in the area. That last one was pretty serious, and we will hear about problems from that one later. Does this go on to now put down an EF0, or does it keep it together and drop another 3? Outflow dominance has been the theme of the day.

If I had to guess, looking at the echo tops, these storms probably have stronger updrafts than last week. That would make some sense, we aren't lacking instability. Last weeks storms had more spin and low level shear, but updraft strength wasn't as strong (iirc). Also, what we define as "a lot" is subjective. I haven't seen a "lot" of anything today. A lot of crudvection, yes.

Welp, that couplet is going directly over Fort Polk. I don't remember what the 88ds are rated to withstand. I do recall the dome is several tons, they're doing upgrades on KDIX soon and read a notice a couple weeks back about a crane needed. Who needs a dow truck? Edit: ah I can still see the couplet se of the radar site. Wow that's close.

Not necessarily. What that reads to me as is, we don't think there will be many tornadoes, but the tornadoes that do occur, will likely be strong. That makes sense, given what has been discussed about storm mode above, and questionable sfc conditions, but concurrently, favorable overall dynamics and elongating hodographs. Fwiw, models do show things getting more favorable late afternoon early evening. This whole event, while thus far a snooze fest, has been excellent educationally. It's a complex forecast over a huge area with multiple storm modes, risk types, surface and elevated convection including storms transitioning from one to the other, upscale growth, areas of veering wind vs backing wind, etc. Sometimes in the plains forecasting is almost perfunctory on a gangbusters day. This setup is making everyone have to think, I know I am.

Can someone take a look at the storm near Lenox GA and tell me what they think? KVAX is showing a TVS but it is far from the radar site.

Ok, yeah that makes the most sense actually, especially if the trees recently leafed and some still have flowers etc. Thanks guys

I'm almost wondering if that isn't a tds actually, or, if it was, wasn't indicative of the size. Could it be straight line winds, some ground based phenomenon, flowering trees all blown up by a small spin up creating unusually strong returns.

Oof.

Jojo, I agree with you, though I lack a crystal ball, ef2+, this ain't/was not striking me as, right now. But there are a few reasons for weak-ish low level radar returns. It's been several years since I took meso and went a different direction since then, so, ya know, I'm rusty, but.. when you have a super classic hook like that, you can get a spin up or two. WSR88ds are great but not infallable. Just like model analysis, and idk why I'm telling you this since you know it better than me, you look at all the data. What's holding it back right now appears to be a lack of singular focus for low level rotation. I'm personally more interested in the development of a meso closer in on the flanking line, not the one that produced the spin up..if something sig were to occur. Environment is there. Again imma preface that by saying I probably don't know what I'm talking about. But I think it'll produce again, and I think nws does too bc they extended the warning.

It is confirmed on the ground now.

Classic hook on HGX. Can't upload image because file size is too big. Took its time didn't it? Looked like it was fizzling for awhile, interacted with another upshear storm, developed new low level rotational foci. Keep your eye on the CC panel.

Storms SW of Houston do need to be watched. Mesoanalysis trends are favorable for further development, STP is high. Things are starting to light up at this point all over east TX and southern and western LA as diabatic heating increases amidst already high dew points and strong(er) deep-layer sheer. We're heading into the active part of the day--whatever that ends up meaning. I see I've been beaten to this as well by a bunch of folks but I was waiting to post until the two cells had finished merging to see what happened with that interaction before sounding a fool. Looks like a couplet is forming right now so any chaser in that area is probably seeing a developing wall cloud. Ignore the second attachment, the first one is the newer update.

It's not PDS due to the EF2+ odds. In watch 110 it was 95/90. Here it is 90/70 over similar areas. Difference between a "couple" intense tornadoes, and "several" intense tornadoes. Not saying whether or not that's right, just guessing why the issuing met didn't choose PDS language.

I mean it is clearly a high risk writeup with a moderate forecast cone. It's almost comical to read.

Mkay, think this is a sound call. Few thoughts--this isn't wishcasting. There isn't enough confidence here to issue high right now. They can absolutely go high in the AM if they need to. Broad area of SOME risk, different than concentrated area of HIGH risk. Once we see how things shape up in the AM, there will be a better handle on the setup. I'm going to play the reverse card: if tomorrow is a bust, would you rather it was a high risk or moderate? You can always up your warning language, hard to go down. For the public, this will have the same warning language and be communicated effectively, and that's what matters. There is 0 chance anyone who hears about this, in the public, will act differently, because the risk is moderate (aka 4) instead of high (5). They don't know what that means. This is for emergency managers. And they can get the last update in the AM. No one is going to die because a moderate was issued instead of a high. The same person will or will not die. I hope that the rumors I read that Birmingham doesn't want a high period bc this isn't as severe as last week's setup, period, no matter what, isn't true though. That similarly shouldn't have any bearing here. Statistics are statistics. Either your probability is high enough or it isn't. However I'm guessing bc it covers some of the same area, they advocated that lower risk shouldn't be articulated as higher risk. Sigh.

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Messy forecast. Could go either way. High end potential is there. Easy to bust. Some may depend on what you define high risk to be. Technical definition of probability of a tornado within certain distance, vs. large potential area of strong tors, multiple rounds and foci, and two modes (isolated cells, QLCS's). Clearly, going to be an active day for the south. The corrected HREF probabilities are sort of telling--a conservative model showing a very high cumulative risk. Conditionals favor a moderate, at any given time, BUT, overall setup favors a high. The risk at any single point in time may not meet the 30% guideline, but it is possible that the cumulative 24 hour period WOULD justify it. However... bust potential also high. So, do they issue a high tonight, or stay moderate and change it in the AM, as was floated last week but ultimately never done? Beyond the nerd factor, high risks get carried pretty widely across the media. You don't want to play boy who cried wolf, we've seen high profile high risk busts. So before issuing a high, you want confidence that basically sounding your red alert alarm is warranted. People won't pay attention if you overwhelm them with too many warnings. I think, if you're the SPC, given the data, high risk is justified here. It was justified last week too. But it's hard to argue keeping a moderate until the AM. Edit: Re crying wolf. Here's the thing, this is a philosophy question. The reason you don't over-warn, is because you get warning fatigue. I live in Philly. People DO NOT change their behavior when even a tornado warning is issued. At ALL. "Oh my phone just said there's a tornado warning *proceeds to go outside to go run x errand*". I've seen this a lot. When everything is a severe thunderstorm, nothing is, until it's on top of you and, oops. The public is constantly being distracted with many different stimuli. As with a tornado emergency, you can warn a tornado that may kill people, and is large, with an emergency, or pds warning. Death, however, does not justify issuing an emergency, or a high risk. They are not related concepts. Many things are deadly, and they are not related to probabilities. You can absolutely say, this storm is dangerous and may kill you. That's quite different from a high risk of someone experiencing that in a given area. And that matters, because if 90% of your warning group sees nothing, they WILL NOT pay attention to the next one, which may NOT be so kind. Does not matter if 10% saw destruction, the 90% do not equate that to mean them. Similarly, tornado emergencies are best used when a big tornado is striking a large population center. A tornado warning, should be sufficient to tell people "take cover". Dixie alley is not a place to use your finite "pay attention to me" ammo, unless you really feel you need to. Otherwise, use a lower tier, and warn the heck out of that. In a nutshell: people dying is not sufficient for high risk (sad to say), and people will die tomorrow. Somewhere, in the south, a storm, in a 24 hour period, will kill someone. We don't know how many, or where. That's the truth. However, you risk more people dying in the future if you warn too strongly, and it doesn't pan out. Hence, this isn't just a forecast question. It's the trolley problem. Next Thursday remains another, uh oh, kind of possibility. Do not use your ammo, before you need to. Given who is writing the outlook, high risk is certainly likely.