bjc3395

Yesterday was the most difficult, successful and ultimately rewarding forecast/nowcast ive ever made while chasing. We woke up in Dighton, KS. Original target was Syracuse to hedge between W KS and N TX PH. Ended up favoring the panhandle and committed to it at 18z. Problem was N if I-40 was getting rocked and stabilized by elevated junk. So - again at 18z - we committed to roughly Lubbock. This was like a 4.5 hour drive, definitely pushing it. But RAP profiles had us confident it would pay off, given favorable multi-CAM ensemble/deterministic trends and observational/satellite data. About an hour from Amarillo it was evident it would be tough as it was very stable looking. We saw CI imminent as large scale ascent (LSA) - evidenced by increasing coverage and depth of Cu behind the dry line - began to spread towards the dry like. The configuration of the ascent was quite linear and favored rapid upscale growth. We abandoned the NE New Mexico target because of convective coverage and terrain, even missing a few tornadoes due to it near Clayton. Farther south, deep into the 2% tornado risk and severe watch, we noticed CI attempts ahead of the linear LSA. The first few were not very robust. However the subsequent attempt did it and a sustained updraft was born. Slowly, it matured and eventually began a right deviant motion. Behind it renewed updraft development occurred but nothing could sustain. Its right deviant motion meant that it would remain discrete, even as LLJ kicked on towards the evening. A classic Great Plains tornadic supercell looked to be developing. We arrived on scene at roughly 2345 Z I think. A persistent, identifiable cone lowering was evident behind a rain curtain. Could’ve been a tornado, I don’t remember. At some point the storm began to reorganize and a landspout appeared, with swirling dust beneath it. Confirmed tornado warning was issued. Whatever. As low level flow began to increase, winds backed from SSEly to ESEly, possibly a response to the storm scale pressure falls owing to rotation in the low level mesocyclone. This supercell was extremely organized, with pretty stunning structure to go with it. It was obvious, however, it was encountering a bit of inhibition and RAP profiles suggest the same. I had thought tornado potential was all but over at this point. Out of nowhere, a ragged, well defined wall cloud showed up behind it. Indeed a new supercell had just blown up in supercell #1’s tracks! Even as this occurred and the first cell was dying, a weak funnel/possible tornado developed. The rotation on the new cell very rapidly strengthened, perhaps aided by storm 1’s outflow. The mesocyclone rapidly expanded in size and it was obvious this storm meant business. The wall cloud increased in rotational velocities, some of the fastest I had ever seen. Little ribbons of vorticity began to fill in/touch the ground. A rather large tornado was about to develop, it seemed. And then it happened - a tornado was born. This all culminated in one of my best iPhone shots I’ve ever had, lol. Unfortunately didn’t have the camera on me. Long story. But anyway, what a day. The many adjustments and the fact we had so much stacked against us - but just enough confidence to say “we can get this done” made this the most enjoyable, satisfying and rewarding chases I’ve ever had. Like 5 chasers were out there with us. This day will be hard to top.

Today is a difficult chase target for a litany of reasons both meteorological and non meteorological. I’m choosing to head for Norman. I don’t want to deal with the flooded/closed roads in NE Oklahoma and SE KS. Once again I think supercells will track along the zone of ascent causing destructive interference and less than friendly chasing. Throw on top of that increasing flash flood threat 00-03z and chaser convergence for SOC bullseye and I’m out. Grabbing lunch in Norman and watching for anything SW-NW of I35. Tomorkw looks far better. Currently targeting liberal/DDC/AMA. Largely rinse and repeat Friday - Monday/Tues/Weds

Agreed. And anyone who says “it was X” is a fool. You can’t possibly know. The overlap between low level lapse rates for strong, tornadic, and non tornadic supercell cases is so big I’m not sure LL lapse rates are a good discriminator lol.

Re: tomorrow. There are some hints of CI from QPF trends on globals. SREF highlights potential too. HRRR is most aggressive. Maybe from overmixing? Is that still a bias with the HRRR? If so that would explain the convective scenario it depicts tomorrow vs the rest of CAMs

Also see way too much defensiveness from SPC/NSSL/NWS folks after a bust. Just admit it was a bust! Don’t try to tell people how 20+ QLCS tornadoes verify a forecast that called for discrete, long track violent tornadoes. Sure you may have quantitatively verified your forecast - but not qualitatively. Right for the wrong reasons if you will. And I’m not even talking about yesterday, either. I just wish people had more humility sometimes. Every time we have a giant overforecast like yesterday the masses/fanboys come rushing to the defense of them like they’re being attacked. Come on folks. I have had my share of bad forecasts and been criticized. And yet I was better for taking the criticism to heart and analyzing what went wrong. Not to say SPC guys should listen to criticism on Twitter. Whatever to that. But I do see a lot of this weird wagon circling every time there is a forecast bust. It’s okay to bust. They happen. Just look at Roger Edwards’ tweets today as a great approach to it.

I’m an operational meteorologist who has done a research stint w/SPC before. I should have clarified what I meant. I would’ve issued the same high risk forecast Edwards did. We lack the obs network to avoid busts like yesterday. That fascinates me. I am skeptical the capping alone did this event in. A comparison to BMX 18z sounding from 2011 shows an astonishingly similar profile. Same cap. It was probably a mix of multiple moving parts. It just didn’t come together. There were attempts at CI along multiple confluence axes that just didn’t pan out... this was for the better. Just to clarify. Yesterday 100% was a bust, and a massive overforecast. Will probably end up verifying no more than a 15% moderate risk. Criticism is fine - we all make mistakes. My forecast busted just the same. Should I get all butthurt about people calling it a bust on social media? Absolutely not. It is part of the business. We learn and we move on. So i repeat. We have much to learn!

This event is wildly fascinating to me. Extreme CAPE/shear combo and largely busted today. We have much to learn.

So you’ve got more experience than me. In a typical Plains setup i would agree that MCS in NW OK pretty much confines the front to I-40, maybe even S. But.. this is anomalous for the Plains. Would argue the LL flow keeps that boundary N of 40.. perhaps closer to 412. Your thoughts from experience?

Think the warm front is going to hang up roughly along Highway 412 in OK. Sure outflow will sag south some but anomalous low level flow regime will almost surely keep the OFB from surging south into I-40.

This is one of the few times the trend is going to a worst case scenario.

Probably skewed by CAMs with MCS/linear modes which produce large swaths of High UH usually. But the W TX signal is legit.

I like to use the HRRR as a time-lagged ensemble, and I gotta say.. The trends on the HRRR *aren't* pretty. Potentially historic setup tomorrow.

Not necessarily discounting them but I think we get a long lived supercell event. At least til 3Z. That assumes the front isn’t shunted to ~red river or further south. Looks pretty big time. At worst I think we are looking at a mixed mode by 01z or so. We will see. Think we all agree there’s a very high ceiling.. but definitely a low floor too, relative to many expectations. Another day that has my attention is Wednesday despite rising heights. Seems globals show hints of diurnal CI along the dry line... environment is pretty ripe for tornadic supercells if we pop a few off.

At this point - glancing at summary of 12z guidance... I think so long as we don’t get a warm sector crushing MCS... this is bound for a borderline historic outbreak of tornadic supercells. I know that’s crazy to call >24 hours in advance, and I’m by no means saying Dixie level historic. But for plains events, I think we are headed for something very high end.. bordering on history making. CAMs are not built nor able to properly resolve discrete, propagating supercells.. this could easily be a long duration tornadic supercell event across E TX PH into W and C OK, and NW Texas. TTU WRF and NCAR ensembles show a strong signal for discrete modes maintained well after dark - into 5z. Again.. the CAMs you can access for free on pivotal.. especially the 3km NAM.. are not going to resolve tornadic supercells or a discrete fashion for long. Personally this looks like a pretty prolific event - but the uncertainties as mentioned above preclude a high risk until perhaps even the 10 am update. But I think this is shaping up to be a memorable, long-duration tornado event.

In my honest opinion, what sets this apart from the 4/13 "bust" is a prominent focus for surface-based convective initiation: the dry line. If you had a surging dry line into eastern TX with favorable shear orientation, I imagine that day plays out much differently. Instead we didn't exactly have that and storms were initiating but not exactly well-rooted into the surface, nor organized. I think that is a key difference, and the CAMs across the board are depicting varying solutions that all kind of converge on a mixed-mode severe weather outbreak by/after 00z. Agree that a day 2 high is too much. But don't think a day one high is out of the question yet. Threat for supercells producing significant or violent tornadoes should carry well into dark with the strong theta e advection. Boundary layer stabilization should be offset some.