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Severe WX Severe Wx Outbreak March 1st- 3rd, 2023 - Southern States, MS/OH/TN Valley
- Thread starter KevinH
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Yeah, just because the environment Is not as extreme as once thought, cells like these could still produce a violent tornado given the right conditions. I wouldn't merely focus on this being a high or moderate risk area. Those are only for high confidence in tornado outbreaks ... Doesn't necessarily mean you won't have a violent meaningful tornado just fyi guys
For example... Beauregard system was only enchaned, Mayfield was only enchaned, ef4 that hit Tennessee was what only slight? Conditions are still very favorable for significant storms that if conditions are just right a violent/strong tornado is highly possible.
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That was one of the factors I kept seeing pop up over and over on soundings leading up to this were those weaker LLLRs.If you get a cell or two riding the warm front up in southern Arkansas where the shear would be enhanced you could get a sigtor threat there but yeah the open warm sector doesn't really look like it's going to amount to much.
I'm not sure why a parameter space like this isn't producing any convection but yeah. LLLRs aren't great but there isn't much capping to speak of. Seems like it should produce storms, and yet.
Low level lapse rates are key to supercells, as a steep low level lapse rate will provide the best updraft in the shear-bearing section of the storm below 3km, making for the highest enhanced helicity index.
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Not necessarily meager to moderate are actually some of your best lapse rates for events like these in the low levels. High low level lapse rates are needed when you have a lot of dry air or a very stout EML if I'm correct, somebody correct me if I'm wrong.
I think the moderate area on that day should’ve been shifted to the East. The environment on that day checked all the boxes, I think the SPC said the only reason they didn’t go high on risk was because they hadn’t really seen that type of environment in December, feel free to correct me if I’m wrong but I thought I read that somewhere.
TornadoFan
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Small enhanced risk for wind added for tomorrow.
I honestly don't think its an issue with the environment - the CAPE/Shear combo across N AR and S LA is still very impressive with STP on soundings in the range of 4-6, it's just the fact I don't think we are going to see any storms actually utilise that environment fully. Most of the soundings I'm pulling have 1000-1500j/kg SBCAPE and 300-500 Effective SRH yet a stout cap really limiting discrete development.
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Lol I was pointing out to the latest hrrr runs it shows some semi discrete convection that could utilize it, you could have a strong violent tornado if it utilizes the conditions available.
The environment is there but theres low confidence in storms being able to use it, but the HRRR is poking around giving a possiblity to a couple cells
The semi discrete convection shown on the HRRR lifting north on the warm front is in the 22-00z timeframe. The warm front could increase shear locally and produce an isolated strong tornado or two.
Yet the really properly favourable parameter space is going to be 02-6z through N LA and S AR... but no storms are forecast there.
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Not necessarily, your in a battle between losing instability and gaining higher shear in the 02-6z frame but in the 22-00z you have higher instability but some lower shear. Overall things don't look to really mesh well but you don't need extraordinary parameters to have significant tornadoes.
MattPetrulli
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Pretty good thread discussing tomorrow's severe potential
warneagle
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Yeah, this is the part I really don't get. There's a window in that timeframe where the environment should be relatively uncapped and there's sufficient shear and instability...but there just aren't any storms in it. The only thing I can really see as an issue is the lapse rates, so I guess that's enough to spoil a parameter space that's otherwise very favorable?
They're a little bit better once you get up into southern Arkansas and southeastern Oklahoma, and the HRRR does generate some semi-discrete convection there. I guess that's probably gonna be the sweet spot for any kind of sigtor potential, but I'm still confused about the almost total lack of open warm sector development in a robust, uncapped parameter space like that. Maybe a lack of forcing that far away from the surface cyclone? Idk.
At the warm front instability remains relatively similar all night. That being said, looking at the latest HRRR soundings in the vicinity of storms near the warm front it seems shear has trended more significant and now I've pulled a couple of pretty large looping hodos with 300-400SRH, though instability is a tad more marginal right along the warm front. Isolated strong-intense tornado possible I think.
MattPetrulli
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17z HRRR is somewhat improvement showing some semi-discrete cells riding the WF through the afternoon-evening vs earlier runs where that wasn't really the case
17z HRRR with deeper and longer updraft helicity streak on discrete tornadic potential in the warm sector.
warneagle
Member
Yeah that looks a lot more believable to me than the bone dry warm sector on the last couple of runs. I'm sure there's something to the idea that the warm sector isn't exactly ideal (since most of the other CAMs also show limited warm sector convection) but the idea of it just being totally dead during the most favorable window didn't add up.
I think there is a small area in S Arkansas where the soundings I'm pulling are uncapped, and I think this could be the sweet spot like you said, but for the rest of the warm sector I'm pulling soundings with a pretty hefty cap.
Further North though I would agree and think that it would make sense for a couple of storms to develop just south of the warm front... and if there was anywhere I would put a 15%# zone, it would be there (S AR just along and S of the warm front around 00-04z
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My feelings stand from earlier these storms have some strong tornado potential it will be pretty intriguing to watch.
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Think the concern is definitely shifting north for tomorrow given the bulk of recent guidance. Most of the 12z CAMs were indicating the potential for semi-discrete convection with some absolutely hellacious shear towards the Ohio Valley tomorrow. Remains to be seen how unstable things will get, but it is essentially a cold core setup, and mid-level temperatures should be more favorable with northward extent. Oh, and storms will be moving insanely fast if they do form.