I also agree, there seems to be a pretty good model consensus on the shape of the trough and the lack of downtrending too. For example, here's a look comparing models at 18z on Saturday:
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*NOT TRYING TO FEARMONGER* but seeing the shape of the trough, a few examples jumped out to me which I will share below.
Similar to what Andyhb said with a 50kt LLJ in play by 4pm in the plains, bad things tend to happen. I'd like to add that troughs with this neutral/negative tilt ejecting into the Plains tend to lead to bad things happening too. Based on the models, this trough seems like it will have a neutral/negative tilt. However, mesoscale details obviously still have to perfectly come together as well for supercells and tornadoes to occur.
An example of this would be 5/24/11, however, the trough was more amplified, with a strongly negative tilt. The mesoscale details also seemed perfect for this event but we won't know those until the day of, of course.
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4/14/12 also had a generally similar trough shape, however, it was a lot more monstrous of a trough than this one and generally had a more positive/neutral tilt to it. Of course, the mesoscale details also aided this event in becoming what it did.
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And my last example would be the 5/20/19 "bust" which would be an example where the overall trough is very, very impressive, but the mesoscale details did not aid the event in reaching its potential.
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As modeled this event certainly has potential and warrants the D4 30%, and I personally always like looking at historical analogs to examine the range of possibilities. As many others have mentioned the mesoscale details are yet to be seen, and will play a big role in the outcome of any storms.
Would love to hear other's insights on this!