4/29/22 EVENT: NE/OK/KS

Ray Walker

Apr 9, 2022
Long ways out but given latest Model Guidance and climatology I am concerned about this day. Nice negative tilt trough progged to eject out of the rockies and into the southern/central plains Friday. The difference I see with this system vs the past few systems is timing. The timing right now in guidance is perfect for a major severe event in the central southern plains. Not going to say severe or tornado outbreak yet due to the face its a long way out and things will likely change between now and then. However if trends continue over the next few days alarm bells should start going off. It has been a VERY long time since I have seen a setup like this in tornado alley. Something that bears watching.
Just took a quick perusal of the 00Z runs from yesterday evening:

  • Seasonally in-line MLCAPE values along the entire dryline on the GFS AOA 2750 j/kg with the Euro going slightly lower but still showing substantial values above 2500 from the Texas Hill Country to the OK/KS state line.
  • Mid-60s dewpoints surge north out of the Gulf on Thursday morning (4/28) and seem to stay relatively untapped until the day of. There's some noticeable mixing out on the Euro with surface temps in the upper 80s right at the edge of the dryline cratering dews into the upper 50s in spots.
  • Forcing looks a little hard to come by. Both the GFS and Euro sit the trough northwest into Colorado/New Mexico/Kansas with our mid and upper-level winds not responding to the approach before 00Z. This is probably my biggest concern with this setup as the overall shear profile looks good but the high CAPE/weak ventilating winds makes me think hybrid but leaning to HP supercells with big hail. That said, the LLJ is absolutely cranking by 00Z and there's substantial 0-3KM SRH >400 m^2/s^2 along a pretty good chunk of the dryline in Oklahoma/Kansas and into North Texas.
  • Capping doesn't look super ridiculous which is good given the time of year/glancing lift from the trough but it is still substantial and it seems like we may struggle to get anything.
Obviously we're not in range so a lot can change. I definitely am thinking of taking an early leave from work on Friday for this one regardless.
With the lack of upper level support on the dryline target, I'm inclined to default to my normal targeting of the TP/WF, as I'm apt to do. I will admit though that I've noticed a difference vs the 12th that gives me pause. Everything I'm seeing at the low levels indicates more convergence of surface winds along the DL than was present on the 12th. Surface winds essentially being parallel to the DL was a big reason why I was convinced that it wouldn't fire at all that day. Not so much with what I've seen so far for the 29th. I'm not sure if that'll be enough to get more than a couple storms to fire, but given everything else, that may be all that's needed.

I generally favor warm fronts over drylines for my own targeting (which I know isn't particularly common among plains chasers), but I will have to do my due diligence and not rule out the DL out of hand before I make the drive north to Kansas.
Yesterday's 00Z runs seemed to have changed their stance a bit on the trough positioning/ejection timing out of the Rockies. I'm still unsure if it'll be enough to breach the cap in Oklahoma but the Euro, GFS and NAM all shifted the trough into a more favorable position over the Panhandles/SE CO with better forcing for ascent along the dryline north of the US 62 corridor. The TP still appears to be the most obvious play for just getting initiation but the shear parameters in Oklahoma and southern Kansas are bonkers.

The Euro appears less willing to develop a sharp dryline, with the best moisture/instability displaced off the leading edge of the boundary. However, both the GFS and NAM paint a pretty different picture with persistent return of mid-60s dews and MLCAPE values exceeding 2500 j/kg. The NAM's instability axis is noticeably more narrow with eastern extent than the GFS but that doesn't seem like something to worry about until day of.

The triple point/just south of the TP seems to be the best bang for your buck option in terms of tornadoes as it stands but that conditional threat in Oklahoma is extremely tempting.
12z GFS is showing the main 500mb trough a little further south and east than previous runs. Add in that both the GFS and Euro have a lead 700mb SW time up nicely over Oklahoma around 21-00z, I think we will be able to get initiation. Looking at 3000+ CAPE and increasing shear after 21z, we should have a potent environment in place. This one definitely has my attention.

The 3im WRF,. which has performed well in the Great Plains so far this season, is extremely bullish about Friday. Here is the forecasted sounding for 4pm Friday over Hesston, Kansas.

I also like that the models are forecasting morning rain over the eastern half of the state. I did a research project that indicates that violent tornadoes are often preceded by rain on the morning (11 years ago today in the South, the Andover Tornado 31 years ago yesterday and many, many others).


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The 3im WRF,. which has performed well in the Great Plains so far this season, is extremely bullish about Friday. Here is the forecasted sounding for 4pm Friday over Hesston, Kansas.

I also like that the models are forecasting morning rain over the eastern half of the state. I did a research project that indicates that violent tornadoes are often preceded by rain on the morning (11 years ago today in the South, the Andover Tornado 31 years ago yesterday and many, many others).
I think a lot of time the morning rain helps stabilize the atmos a bit so that the strong forcing from bit time systems don't fire off storms too early. So many time I have seen the perfect setup, but then the forcing is so strong that instead of discrete supers we get a very substantial squall line. You want a little big of cinh to keep things discrete, but not too much that storms don't pop.

Is this a Mike Smith that know Dean Schoeneck and used to work in Dodge City?
Several things I've noticed the past few days with regards to trends in guidance. First thing is the Euro trended towards the GFS several days ago. Second the GFS has started trending in an ominous direction as of last night. This ominous direction I'm talking about is a deeper, stronger trough. A stronger upper/mid level Jet streak rounding the base of the trough and ejecting out across the plains with strong divergence aloft. Several days ago the global models were showing weak winds in the upper levels around 300mb of around 30kts and only 35 to 40kts in the mid levels across Oklahoma and Kansas. Also at the same time the models were showing the bullseye of this jet streak swinging in and out across the main body of Kansas. However with recent runs of the GFS these winds are not only stronger with each run but MUCH stronger. Now we have upwards of 60kts at mid levels across Oklahoma and parts of Kansas with a 70 to 80kt core punching in from the High plains. Also the GFS has slowly been trending more south with this main mid level jet. The winds at 300mb are also MUCH stronger on recent runs pushing or exceeding 80kts. you can clearly see this jet already on WV imagery on the west coast. This is concerning because from the trends I'm seeing a MUCH stronger mid and upper jet from several days ago up to tonight means models are picking up on a stronger NEGATIVALY tilted system swinging through the plains with ideal low level shear for supercells and tornados along with good thermodynamics. The EUROs 12Z run still has the main jet across Kansas however the GFS has been MUCH more reliable so far this season with these systems. Also several CAM runs tonight seem to be hinting at a similar situation as to what the GFS is showing. If and its a big IF right now especially since we are still days out and the system is still off the coast but IF the GFS is onto something and its trends continue i would expect AT the very least a few VERY significant supercells from I40 in OK up towards the Wichita Ks area Friday evening. If that happens given climatology/synoptic pattern and the background conditions tornadoes would be likely. If the EURO solution is more realistic then I would say NC into NE and Central Kansas into southern Nebraska would be the area to see sig severe. Either way looks like Friday should produce supercells with a heightened tornado threat over at the very least portions of the central plains. Very interesting setup. This drought has increased the capping issues but I don't see capping being much of an issue Friday at least up into Kansas. Very interested to see how the CAMS and the Global models handle this system over the coming days and if the GFS is onto something. Going to be a good chase day for at least a few come Friday.
@Drew Terril you are not alone in favoring warm front targets. Always an interesting decision process as to whether to take the option on a more conditional but potentially better (more discrete, classic, etc.) storm on the dryline , versus more likely but potentially messier storm mode near the triple point…

A couple of days ago I would have leaned toward the triple point for this event and targeted generally in the SE Nebraska area. But now the GFS shows a veer-back profile in that area. I wouldn’t necessarily call it veer-back on the Euro, but 500mb is somewhat meridional there. It looks quite cool on the north side of the warm front. Meanwhile, the cap seems breakable on GFS at least as far south as the KS border possibly into northern OK, and the position/orientation of the mid-level trough is better there. Nice sharp dryline on GFS. As @James Gustina noted, the dryline is not nearly as sharp on the Euro, which anecdotally seems to have been the case with the previous one or two setups. One concern is the surging cold front, could this overtake the dryline in KS?

At this point my armchair chase target would be somewhere around Ponca City, although if I were actually chasing I would have to weigh terrain considerations. I really would not want to have to chase east from there…

Edit: Wrote the above before reading SPC Day 2 issued 06z on 4/28. They note that CAM guidance (which I have not yet looked at) leaves an outflow boundary from prior convection across southern KS. Obviously something to look for on Friday and would certainly be a reason to adjust my target northward, where the terrain is also at least a little better.
I'm tentatively planning to eat a late-ish lunch in probably Blackwell. I can't make the play on the TP, so I'm just going to have to hope that outflow boundary that's been mentioned has an influence on things before the cold front comes crashing down. But from Blackwell, I'm near two of the major river crossings via US-60 and OK-11, plus have ample routes north or south via I-35, US-177 or US-77.

Only a handful of Arkansas river crossings between Wichita and Tulsa, so those not familiar with the area should do some map study tonight and in the morning. IIRC, only a couple of those (aside from the old US-60 alignment across Kaw Dam) are not a numbered state or US highway, but there are few enough of them to create issues.
17:30 SPC notes potential moisture quality issues and you can definitely see the shallow moisture, with low RH at 850mb particularly in OK on the GFS. Even NAM, which usually has a bias toward higher moisture, hints at this. NAM and Euro have higher RH in E OK but that’s in the trees. I found it hard to get more than a marginal TOR sounding just east of the I-35 corridor in my area of interest from Wichita to Ponca City.
Interestingly enough, the observed 00Z sounding at OUN showed some solid moisture depth up to about 2km, or halfway between the 850 and 700 level. I'm not as worried about moisture as I am forcing. And even the CAMs are traditionally very poor at resolving old outflow boundaries for a given day. 00Z FV3 is already showing to be worse on moisture at the 850 level than what's being observed, so I'm not going to put much stock on models for this one.
Not truly related but something to think about. Check out the subtle SW currently moving across N. Texas.

You can see it on the mid-level WV. If you switch over to the Vis you can see it created a mid-level HCR. This HCR was the focal point for numerous attempts at CI. We did finally get some convection and a few bolts of lightning. End the end the cap is to strong.

So when it comes to tomorrow, look into the fine details to see if there are any subtle SWs, or perhaps an OF boundary that could be the focal point for initiation.

Fingers crossed we can see that.
Well sports fans, the latest calibrated SPC guidance is of interest, especially since the #2 analog to tomorrow (I would say #1) is May 8, 2003. The forecast I posted on my blog at 5p had the highest risk farther north but this certainly isn't out of the question.


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