2024-03-24 EVENT: TX/OK/KS

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In the spirit of recent threads decrying social media stealing real-time discussion from ST, I'm making an effort to post thoughts on some Plains days of interest this year... we'll see how long that lasts!

A major trough ejection out of the Rockies is on tap for Sun 2024-03-24. Across the N Hemisphere we see a relatively high wavenumber pattern, which typically isn't ideal early in the spring when moisture is scarce. Still, NWP progs for Sunday show a very impressive trough resulting from some degree of phasing between the polar and subtropical jets over the SW US during the prior 24-48 h.

With a seasonably strong jet aloft punching into TX/OK, the dryline should be arced nicely SE-NW back toward a very deep sfc low (985 mb range) in W KS by 00z Mon. Dynamics and kinematics appear excellent for high-end severe weather. Moisture, of course, is the limiting factor... and with progged dews ranging from mid-upper 40s in W KS to low-mid 50s near the Red River, that limitation will be significant. It's common to hear chasers say "if only it were May" this time of year when 80-kt flow aloft and 40-kt LLJs are easy to come by. Sometimes that's just silly, but in this case it does sting... because it's not like we just had a Gulf-wiping front recently. We've had a relatively quiet, warm period this week leading up to the event, with mid 60s dews already sitting on the TX Gulf coast. If only the downstream wave weren't amplifying significantly this weekend over the SE US, we could probably manage enough moisture for respectable tornado potential. But, as it stands, we will be dealing with marginal moisture even relative to the seasonably cool temperatures aloft.

MLCAPE by late afternoon appears likely to range from 500-1000 J/kg along the most unstable segments of dryline, quite low by Plains chaseability standards. The marginal instability and moisture coupled with large, looping hodographs scream "structure chase" to me. The good news is that strong forcing should eject into the warm sector during the afternoon, so daytime convection is all but certain, barring an anomalously significant slowing trend for the lead times we're now at. IMO, the probability of supercells with decent to good structure by sunset is considerable. The Hollis, OK, supercell on 2019-04-03 is a good example of dynamic early season setups with similarly sad moisture coming through in that regard.

I would not rule out a low-end tornado threat around sunset, simply because this system is so dynamic and 500-mb temperatures as cool as -22 C are progged to punch over the dryline. But in general, this looks like a setup worth considering for structure fanatics and/or people within a few hours' drive... not so much tornado snobs. As of now, you could argue for anywhere from SW KS (best dynamics and cold punch aloft) to NW TX/SW OK (least objectionable PBL moisture). My hunch is that northern areas will be the better long-shot tornado target, whereas the safer structure/hail target will become clearer as CAMs come into range.

A final note is that when moisture looks this marginal and it's only March, would-be setups have been known to fall off a cliff even at these 3-5 day lead times... simply because moisture return that's 3-5 F worse than now progged, or entrenched cold air further constricting the warm sector, turns this into a complete non-event. The very high-end dynamics and vigorous return flow on Sunday should make that unlikely, but it's worth noting.
 
One thing I'm noticing with this one is how low the 500 mb heights are over KS and N OK for a non-traditional cold core setup. They are pushing into the 540s on most of guidance, which is very, very low (and suggests very cold air aloft). Lapse rates are certainly going to be doing the heavy lifting in this scenario with the absence of moisture. There is appreciable low level buoyancy on most guidance with very steep low level lapse rates. Might be enough to squeeze a few tornadoes out of this especially closer to the surface low. It's not a true cold core setup, but thermodynamically, it might behave like one.
 
ECMWF: 7p Sunday has a 978mb (29.88") low over Hamilton Co, KS (inside the Colorado border west of KGCK). Warm front extends to KOFK. Dry line from the low to KDDC - KP28 - KCSM - KSPS. The left front polar front jet stream at that time will affect the S. Cent Kansas and northwest OK area. The same area will have instability of as much as 1000j at that time. Like with the Alma Tornado, Pw's will are forecast to be above the climatological average by about 0.2 inches.

The same model has thunderstorms with high rates of lightning at 7pm in that area after thunderstorms farther west a couple of hours before. The latter produces some rotation tracks per the 3km NAM.

Given the cold aloft relatively dry air near the ground, the chance of hail and strong thunderstorm-generated gusts seem pretty good. However, the chances of a tornado seem pretty low, in spite of the model forecasting 311 0-1km SRH over KICT.

If, somehow, more moisture becomes available than it looks at this point, the chances for a tornado would be quite good as everything else is favorable.
 

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The 00z model suite (sans the Euro, yet to come in) maintains much of the pessimism about the moisture situation. Prior hopes for some pooling assistance on the northern end nearest to the low increasingly don't seem to be realistic. Yet even as a chaser living 7+ hours away from this, it's still hard to ignore the wind profile and the depiction of healthy supercells now by most every model (including CAMs). I still have to suppress the impulse to go, recognizing the (albeit slim) potential for an overperforming cell to produce a fleeting, rogue high-based beauty somewhere in that area.
 
Well, things have taken an unexpected turn........

Our friends at NADOCAST ( ) are forecasting a big day -- with a strong tornado risk -- and isolated 15% probability on the KS-OK border. I have found NADOCAST to be quite reliable.

The moisture is forecast by the ECMWF slightly better than originally forecast. As I previously wrote (above), moisture has been the only missing element.

I went back to last week and the dew points were in the 55-57 range in the initiation area for the Alma Tornado. Tomorrow, thy are forecast to be in the 53-55 range. Precipitable water is forecast to be right around 1 inch, which is well above climo and, exactly that the TOP sounding measured at 00Z before the Alma storm.

The STP is as high as six which is very high (second from left)

The third from left is the lightning forecast (ECMWF) for 7pm. At far right is are the o-3km helicity tracks.

This is a narrow threat area but if the storm movement is fro 220° as forecast, then the storms should be able to stay in the favorable area for a while.

If I had to issue a tornado watch, it would be 50 mi either side of a line from 25 mi north of HUT to 40 SSE of END.

Before I forget, Sunday's sunset in Wichita is 7;46pm (0046Z).

Bottom line: If you'd like a chance at a photographic, high-based storm then tomorrow may be your day.
 

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Now that numerous CAMs cover the timeframe in question, they're hinting at a potential issue that may not have been apparent in broader-scale forecasts: widespread CI may occur up and down the dryline around 20-21z, but even modest moisture is still trying to stream in at that point, only reaching the values widely expected by chasers (e.g., widespread low-mid 50s in OK) at the very last minute around 23-00z.

As a result, many CAMs currently depict small cellular convection that races out of the instability axis an hour or two prior to ingredients falling into place, unceremoniously dissipating along the I-35 corridor by dinnertime. This, I'm afraid, is one particularly nauseating path to something like the "non-event" scenario I mentioned at the end of my last post. I would still lean toward a >50% probability of getting at least one robust storm that comes off the dryline during the 22z-00z timeframe and attains real supercell characteristics. But given the combo of storm motions and the length of dryline in play, setting oneself up to intercept that storm may be a stressful proposition.
 
The software would not allow me to update my post above. This Andrew Brady's tweet from a few minutes ago showing that a second objective method have some to nearly the same conclusion as NADOCAST.

For planning, Wichita gas prices are currently $3.19.

Happy....and, safe....chasing tomorrow!
 

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A potential secondary target near the Red River in SW OK/N TX may be evolving where models depict a dryline bulge with upper 50s dewpoints in stronger deep-layer shear. There is even some pooling suggested that would get DPs to 60F just east of the dryline. The downsides of this area is the lapse rates are much weaker and sustained storms before sunset are in question.
 
Photos here

More
 
Another Unwarned, And Obvious, Tornado
The story is here: Kansas EF-1 Tornado With NO Warning

If you wish to contact your Congresspeople, please do so!

Was discussing this with some folks on another weather forum and someone pointed out that NWS offices seem to be developing a pattern of explaining away missed warnings by downplaying the tornado as a "landspout" or some such (even though a landspout meets all the criteria for being a tornado by definition), as if only tornadoes originating from a supercell's mesocyclone are worth warning for.
 
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