2025-05-19 EVENT: KS/OK/TX/MO/AR

[Jason N]

its interesting given the distance of the convection out ahead of the DL. at 18Z, so I assume it was confluence lines and old OFB' interactions that preceded the weaker DL?

 

[gdlewen]

its interesting given the distance of the convection out ahead of the DL. at 18Z, so I assume it was confluence lines and old OFB' interactions that preceded the weaker DL?

That's my assumption. The Stillwater cell formed near Duncan, OK on an old OFB. I was not looking that far south, having determined that the plan would focus on the dryline in central OK. This is just about 25 minutes into the lifetime of the cell (image extracted from Weather & Climate Toolkit Level 2 display for KTLX 2051Z):

 

[Jason N]

@Jason N Here is the overlay of dryline position and mean static stability for 18Z & 21Z on 5/19 and 00Z on 5/20/2025. It seems that all the convection to the S & E stabilized the lower atmosphere ahead of the advancing dryline between 21Z and 00Z. That's a big shift in 3 hours and includes the period the L-moving cell went through the Stillwater-Red Rock area.

Note: to improve legibility, only the region with Static Stability ≥ 4.5˚/100mb is shaded. Otherwise most of the map would be shaded in cyan. Convergence along the dryline in OK was very weak prior to 00Z.

GOES E/Static-Stability Overlap for 5/19/2025 18Z​

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GOES E/Static-Stability Overlap for 5/19/2025 21Z​

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GOES E/Static-Stability Overlap for 5/20/2025 00Z​

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Individual Plots of RAP Mean Static Stability in Lowest 125mb for 18Z, 21Z, 00Z

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So based on the imagery below, and at the time it was done, can you aim this same analysis at Greensburg 2.0? because looking at the DL imagery, assuming you pasted it, or did you draw that in, I am trying to assess what was different about that area as opposed to northwest OK.

assumptions are:

- increases in height falls after dark
- rapid LLJ increase between 21-02Z
- its the thermodynamics which at least per the RAP still seemed to be in place, but Jeff Duda has me questioning some of that analysis per his earlier discussion about its validity given the lower resolution.
- Did the stabilizing effect of the cloud mass(from earlier convection) just not reach that far and there was a very narrow corridor of pristine conditions. I am just curious what your analysis might pick up on that storm vs. the others

 

[gdlewen]

Not sure what is Greensburg 2.0. Sorry! I did a search for that in ST and did not find anything. I have been away from ST for the past month, so probably missed a lot.... Thanks for your patience!

 

[Andy Wehrle]

Not sure what is Greensburg 2.0. Sorry! I did a search for that in ST and did not find anything. I have been away from ST for the past month, so probably missed a lot.... Thanks for your patience!

Supercell in southern Kansas last Sunday night (5/18) produced a family of intense wedge tornadoes after dark (in very similar fashion to that event), one of which narrowly missed Greensburg proper to the southeast and derailed a freight train between Greensburg and Haviland. Then another impacted parts of Plevna, KS.

 

[gdlewen]

So based on the imagery below, and at the time it was done, can you aim this same analysis at Greensburg 2.0? because looking at the DL imagery, assuming you pasted it, or did you draw that in, I am trying to assess what was different about that area as opposed to northwest OK.

assumptions are:

- increases in height falls after dark
- rapid LLJ increase between 21-02Z
- its the thermodynamics which at least per the RAP still seemed to be in place, but Jeff Duda has me questioning some of that analysis per his earlier discussion about its validity given the lower resolution.
- Did the stabilizing effect of the cloud mass(from earlier convection) just not reach that far and there was a very narrow corridor of pristine conditions. I am just curious what your analysis might pick up on that storm vs. the others

Hey @Jason N--working on this. (Thanks to @Andy Wehrle for the pointer to the event.). There's a lot to unpack.

To answer one question--the dryline analysis I performed "manually" on my computer using a surface analysis plot and then superimposed on the GOES-overlay plots. I would prefer to use the WPC analysis because it is authoritative, but I don't know the projection they use on their surface analysis maps and guess-and-trying my way through and then digitizing their curve was more trouble than doing it myself.