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Severe WX Severe Weather Threat 3/14-3/16

ColdFront said:
@Grand Poo Bah I need you to understand, violent tornados can occur and maintain themselves in lower cape regimes. Dont believe me? Here is a RAP proximity sounding of the Mayfield tornado which has the longest verified track in history. That is barely over 1000 k/j of cape

View attachment 36512

I can hit you with a list a mile long of this happening.
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FWIW, this RAP sounding is likely low on CAPE based off the observations in the area at the time of the tornado. The dewpoint was closer to 70 in SW KY at that time and temperature was 72-74.
 
andyhb said:
FWIW, this RAP sounding is likely low on CAPE based off the observations in the area at the time of the tornado. The dewpoint was closer to 70 in SW KY at that time and temperature was 72-74.
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I agree I have seen the RAP do that in certain proximity soundings. Especially with some of the 4/27/11 tornados when actual obs were much higher.

I was really just trying to use it as an example that you don’t need 2500+ CAPE to have a violent tornado. Like I said it helps, but it’s not a requirement.
 
jiharris0220 said:
All in all, I think we can identify the 6 main ingredients for a super outbreak.

1. Longwave trough

2. Perpendicular orientation of the jet streak over PBL flow

3. Modest forcing

4. A decent amount of surface mixing (drying of low levels) to prevent crapvection

5. Moist mid levels

6. Extreme kinematics

Getting all 5 of these to occur at the same time is why these sorts of outbreaks only happen every 30+ years.
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Given just how dynamic (to the point of chaotic) the Earth's atmosphere is, it shouldn't be too surprising that such events are intrinsically rare by nature. Even relatively small changes in certain places and times could lead to radical changes in atmospheric events. It's possible that, say, 4/3/1974 could've ended up being a fairly unremarkable weather day with a few slight tweaks; conversely, a similarly unremarkable day in our own timeline could've become a red-letter severe weather day, again with only a few tweaks necessary.

In addition, I can't help but wonder what the upper-air parameters were like on the other known super outbreaks (namely 2/19/1884 and 3/21/1932). It's unfortunate that there's little to no such data available from those events, and that we'd have to rely on reanalysis models to ascertain those kinds of things to the best of our abilities.

And along those lines, I also can't help but wonder what other potentially "super" outbreaks occurred even before 1884, but have gone unrecognized as such because not enough (or even any) data was recorded to say for sure one way or another.
 
Tennie said:
Given just how dynamic (to the point of chaotic) the Earth's atmosphere is, it shouldn't be too surprising that such events are intrinsically rare by nature. Even relatively small changes in certain places and times could lead to radical changes in atmospheric events. It's possible that, say, 4/3/1974 could've ended up being a fairly unremarkable weather day with a few slight tweaks; conversely, a similarly unremarkable day in our own timeline could've become a red-letter severe weather day, again with only a few tweaks necessary.

In addition, I can't help but wonder what the upper-air parameters were like on the other known super outbreaks (namely 2/19/1884 and 3/21/1932). It's unfortunate that there's little to no such data available from those events, and that we'd have to rely on reanalysis models to ascertain those kinds of things to the best of our abilities.

And along those lines, I also can't help but wonder what other potentially "super" outbreaks occurred even before 1884, but have gone unrecognized as such because not enough (or even any) data was recorded to say for sure one way or another.
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on the offical OIS scale (how to classify a outbreak as a superoutbreak) there were only ever ... 2 to 3 super outbreak , one is disputed because it wasn't a single outbreak but a outbreak sequence.

1742151369212.png

anything with a OIS score of 250 is a super outbreak
the closest one that is not a sequence is plam sunday 1965
1742151501439.png
 
joshoctober16 said:
on the offical OIS scale (how to classify a outbreak as a superoutbreak) there were only ever ... 2 to 3 super outbreak , one is disputed because it wasn't a single outbreak but a outbreak sequence.

View attachment 36516

anything with a OIS score of 250 is a super outbreak
the closest one that is not a sequence is plam sunday 1965
View attachment 36517
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I really don’t like this by Grazulis. As far as I’m concerned, the OIS is trash. It’s such an apples to oranges comparison for pre EF scale events and even post-2013. Guy has done wonders for the documentation of tornados though. But I have always disliked comparing 20th century events to now.

It’s pretty obvious what the super outbreaks were.
 
ColdFront said:
I really don’t like this by Grazulis. It’s such an apples to oranges comparison for pre EF scale events and even post-2013. Guy has done wonders for the documentation of tornados though. But I have always disliked comparing 20th century events to now.

It’s pretty obvious what the super outbreaks were.
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i do sort of agree , the whole F VS EF scale and different eras will make some outbreaks seem less severe
along with the whole outbreak sequence issue... there is also the issue of what if there are 100+ EF0-EF1 tornadoes but 0 EF2-EF5 tornadoes? it would apparently not be classified as a outbreak...

anyhow currently this outbreak has a OIS rating of 30 making it a low Major Outbreak
1742151852379.png
 
tornado examiner said:
I’m interested in the damage from “oil trough” Arkansas, yes that’s a town name.
Pretty violent night time damage photo’s came from that town.
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Oil Trough is one of the most gloriously Arkansas things to ever Arkansas. It's apparently named after carved-out trees in which the frontiersmen stored rendered bear fat.

Thanks to this outbreak, I learned there's also a Hot Coffee, MS
 
Tennie said:
In addition, I can't help but wonder what the upper-air parameters were like on the other known super outbreaks (namely 2/19/1884 and 3/21/1932). It's unfortunate that there's little to no such data available from those events, and that we'd have to rely on reanalysis models to ascertain those kinds of things to the best of our abilities.

And along those lines, I also can't help but wonder what other potentially "super" outbreaks occurred even before 1884, but have gone unrecognized as such because not enough (or even any) data was recorded to say for sure one way or another.
Click to expand...
We really don’t have any idea of knowing how truly violent the outbreaks of 1932 and 1884 were because of the lack of data and radar and whatnot… It’s not likely, but they could have absolutely been more violent than 4/27/2011. This is part of the reason why I believe the super outbreaks we have seen are not at the true limit of what the atmosphere is fully capable of unleashing. They probably come kinda close, but they are 1-in-40 year events. I can imagine that there are 1-in-1000 year tornado outbreaks that can occur, or maybe even 10000, but that’s getting into territory where the Earth’s atmosphere is capable of changing pretty substantially over that time frame. But since we’ve only been tracking these things effectively for practically an infinitesimal blip compared to the history of Earth, there’s little doubt in my mind that the true fury of the atmosphere is not these events. It’s the apex as far as we’ve seen.

I wish there was a way to rebuild upper air maps of the late 19th - early 20th century monster outbreaks, but we would unfortunately need the beefiest supercomputer ever to even come close to doing so… lol
 
jiharris0220 said:
Maybe, but looking at the soundings between the two outbreaks, there really wasn’t much difference until you looked at the PBL and it becomes obvious what caped yesterday.

Surface mixing would’ve made it too dry for crapvection to form, and looking at how yesterday evolved it’s also clear had it not been for that, we would’ve had many more tornadoes, as well as long tracked ones.

Not saying at all that there weren’t minor synoptic setbacks though.
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Yeah, I definitely agree with you and think the very moist PBL contributed to a lot of the junk convection. That being said, the synoptic of 4/27 was absolutely one of a kind and pretty much perfect, which brings together all of the ingredients much more easily. The position of the trough to the north of the warm sector allowed the robust, strongest EML to overlap the warm sector perfectly. The surface low was removed to the north, and the excessive forcing leading to widespread rain/showers/convection was also removed well to the north. You had essentially a pristine warm sector, with the speed max swinging through perfectly timed with the peak parameter space.

Yesterday, your warm sector was located well to the East and North of the speed max, which as the trough trended slower should have been a clue that despite the similar trough geometry we were looking at fairly different setups. The strongest EML was slightly delayed and if anything the excessive forcing/lead shortwave contributed massively to the very widespread junk convection, over developed the early day stuff and if anything backed surface winds too much so that the highest end parameter space wasn't advected so much into AL when the trough ejection and wind profiles became even more favorable (arguably they were more not super well ventilated and conducive to shorter lived cyclic supercells)

Essentially, my point is, with a broad synoptic/setup like 4/27, the background conditions are already so favorable even with minor limitations the event still performs (for example I truly believe 4/27 would have performed almost exactly the same with moister PBL conditions, just tornadoes would have been extremely grungy). Whereas when the background is not perfect (as it is in the vast majority of cases, like yesterday), you need almost *everything* to go right to get an outcome even remotely close to a 4/27 type day.
 
slenker said:
We really don’t have any idea of knowing how truly violent the outbreaks of 1932 and 1884 were because of the lack of data and radar and whatnot...
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Absolutely cannot imagine sending a modern-day structural engineering team back in time to the 1880s to inspect damage. I think they'd have an aneurysm trying to compare houses from that time and being unable to locate anchor bolts. Not to mention they would probably revise everything down by 3 levels.
 
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