Jason N
EF4
Moist Absolute Instability
here's a link if you feel like reading.
here's a link if you feel like reading.
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- Weather and Chasing
- Target Area
2024-05-06 EVENT: TX/OK/KS/NE
- Thread starter Dan Robinson
- Start date
gdlewen
EF2
I ALWAYS feel like reading. Thank you!
Stan Rose
EF5
From the damage videos in Barnsdall, looks like definite high-end EF-3, probably EF-4. So the high risk was justified, from a chasing perspective your typical hp high risk bust...joel ewing
EF5
Hey Stan.....haven't seen you since that insane "Simla" et al day in Colorado in June '15. Had to have leg amputated (MRSA infection) plus Cancer at the SAME TIME has kept me out of the alley for chasing. Maybe next year finally....I've got a prothetic leg, I can drive again, etc. Do you remember that outrageous Simla outbreak day? You, my cousin Doren who is my steady chase partner Doren from Salem, Mass and I all stood around taking photos of the ridiculously many separate tornadoes in a side-of-the-road stop for many minutes. Remember it? joel ewing
Moist Absolutely Unstable Layer - basically, when you have a saturated layer of a sounding in which the lapse rate is greater than moist adiabatic. It is considered to be difficult to achieve in reality and is often a sign of specific behaviors either with instrumentation or in the atmosphere itself. A sounding might falsely depict a MAUL when ascending through a layer of very moist clouds as the sensor deals with possible microscale wet-bulbing via turbulence with the surrounding air. More often than not, though, a sampled MAUL is real. It requires very strong mesoscale ascent in a moist region, typically in the inflow to an established MCS.
Sean Ramsey
EF4
FWIW chaser traffic was very manageable yesterday, actually barely even registered as something to be noticed from my perspective. But, then again I was actively staying two steps ahead and not hanging out in any notches which turned out to be a great strategy to move freely about.
No. A single violent tornado does not verify an SPC high risk forecast. Forecast probabilities are solely based on coverage of reports, not on intensity. According to the source below, the PP obs yesterday have only verified a 5% for tornadoes so far. More LSRs will likely be added, but it seems extremely unlikely that the max probability contour exceeded will come anywhere close to the necessary threshold for "high", which is 30%.
And while I'm at it, I'll go ahead and toot my own horn of vindication after these PP wind probs suggest a high risk would have verified for wind, just as I suspected in my post early yesterday:
Andy Wehrle
EF5
We saw this at least twice in 2023 with the January AL/GA outbreak and with March 31 (Keota, IA); both featured cells that produced one or more high-end tornadoes for an hour or so while running just ahead of a pursuing squall line, and continued to produce strong tornadoes for at least one or two more cycles after being caught up to and "munched."
Stan Rose
EF5
Hey Joel, yeah that was one of my fav chases! Hoping for another one cause im back in CO now, havent really chased (other than armchair) for the past five years cause i've been busy running my gallery--i quit the NWS 7 years ago to do photography full time. Probably the only thing dumber than trying to be a full-time pro chaser ROFL. Hope you recover well and get back out there, probably next year for me too except for short trips to KS/NE/WY
Stan Rose
EF5
Yeah Jeff, I probably should have been more clear--I meant 'justified' from a public/media perspective and not a technical SPC perspective. It sure looked to me like a high risk bust from a chaser and verification perspective, I even went on record in social media and said it would be one, so I'll toot my horn too, always good to toot one's horn...
Brian McKibben
EF3
This is the old High Risk probability and intensity requirements. Per old standards, yesterday definitely didn't live up to the standard.
A HIGH risk area suggests a major severe weather outbreak is expected, with a high concentration of severe weather reports and an enhanced likelihood of extreme severe (i.e., violent tornadoes or very damaging convective wind events occurring across a large area). In a high risk, the potential exists for 20 or more tornadoes, some possibly F2 or stronger, or an extreme derecho potentially causing widespread wind damage and higher end wind gusts (80+ mph) that may result in structural damage.
John Farley
SupporterRegarding high-risk verification of high wind vs tornadoes, a lot of those wind reports in western MO, when surveyed, will likely be found to have occurred from tornadoes. Have no idea whether that would be enough shift from wind to tornadoes to affect the verification, though I would guess probably not. And would also note that the high risk was not in Missouri.
gdlewen
EF2
P
although a fine point: the Barnsdall tornado was associated with a discrete cell out in front of the line. If I correctly recall the LSR the first reported tornado was in Hominy.
It is ironic that I was in Wellington, KS earlier hoping for discrete supercells ahead of a line and one formed practically in my back yardLast edited:
Jason N
EF4
Warren Faidley
SupporterFor those of you on X, Cameron Nixon wrote a fantastic analysis regarding yesterday's performance.
Color me a little surprised that only 8 tornado reports (at least 3 of which were from the same tornado) flanked by 2 others a few hundred km away was enough to satisfy a PP max of over 25%, but there you go. Technically a high would not have verified for tornadoes based on this PP methodology either, although a moderate certainly did.Attachments
Jesse Risley
Staff memberIt's interesting to see some of the SPC employees chiming in with their theories as well, particularly that the ejection of the trough and upper level jet core were such that storms didn't really move off the dry line perpendicular to the shear but rather sort of trained and interfered with each other. Sometimes I don't think to look at cloud features on chase days as closely as I should, but Cameron made a good point about the mammatus present in the downstream environment and how storms were moving into areas where stratus clouds existed from earlier. I wonder if that could have been another fly in the ointment with convective temperatures previously being shown in the upper -80s, something like maybe around 87°, whereas some of those shallow clouds may have held temperatures back in Oklahoma and contributed towards maintaining some of the CINH too.
JamesCaruso
Staff memberQuestion on the Barnsdall / Bartlesville storm - what is the mechanical lifting mechanism for an open warm sector storm like that? Was it outflow from the line to its west? Or general large scale forcing from the upper trough? Some other source?
And is there ever any real basis for targeting a particular spot for an open warm sector storm (other than a boundary of some sort, in which case it’s no longer really an “open warm sector storm”) or is it pretty much a random / chaos theory thing?Mike Smith
EF5
In the mid-70's, Steve Tegtmeier, a classmate of mine at OU, did a masters thesis of synoptical climatology patterns that lead to tornadoes. To my knowledge, he was the first to document the "dry line bulge" and "isolated cell ahead of a line." In addition, he told us that solid (as opposed to broken or scattered) lines were less likely to produce major tornadoes. All of this information was new.
Since, I've found his findings to be invaluable when warning of tornadoes. I can't state the physical mechanism for the "supercell ahead of a line" but it -- tragically -- works like a charm.
Jason N
EF4
That was one of the topics discussed prior to the evolution of the High-risk day was the crossover wind orientation from 850 to 500. I noticed and mentioned here about the clouds and ConvT as the day was unfolding as well. I think as you said above, the Anvil overspreading over a more SCT/BKN low level that didn't clear out enough in advance to spike temps may have limited some of the dynamics below the LFC maybe since I think everything above that was certainly more than favorable in terms of large scale lift and shear, and as mentioned by several here now, the timing/location of the initiation, and perhaps sub 1km wind vorticity generation issues IVO the CI location, but that's just a guess there.
Jason N
EF4
I was watching the observations and radar, and I am not 100% sure, but it appeared as though there may have been a confluence line that initiated the cells, and at the time when they first started to loft, the LLJ was peaking out in a clear zone undisturbed by the line to the west. I didn't see any outflow influence at the time they fired offPatrick K
EF0
I’ll offer my late thoughts while I wait on a delayed flight. Most of this has already been said in some capacity but here are things I noticed in the OK target area while virtual chasing this event;
1. Storms appeared outflow dominant on radar. I’m curious if this relates to some of the other observations/thoughts.
2. Timing was slightly misaligned with TEC-like storms forming more westward/later than ideal to take advantage of peak heating (which didn’t really materialize as expected anyway)
3. Related to #2, storm orientation was skewed more parallel to the dry line rather than orthogonal as expected. It also seemed like storm motion was slower at times and the combined effect was interference between supercells before they could fully mature and/or become surface based.
4. Once we got an isolated supercell in NE OK, it did go nuts before being absorbed, even despite IIRC appearing to be a bit of a left mover (correct me if I’m wrong, but I thought SRH would be maximized for right movers)
All in all, another tough situation for SPC, getting people to take high risk days seriously.Similar threads
