I posted this in the severe weather thread, but this thread is typically more active so I figured I'd put it here as well in case anyone here would want to take a look, very interesting work.
If you've never heard of the OMEGA project lead by SPC forecaster Chris Broyles, take a look through this paper to get an idea of what could be the future of forecasting high end/High Risk tornado outbreak days:
https://www.spc.noaa.gov/publications/broyles/omega.pdfIn summary, one of the main things they have looked at is jet translation speed, with a speed of around 40kts or higher being considered favorable for a high risk level tornado outbreak. If you've noticed they've been mentioning jet translation speed at times this year, this is likely where they are getting that from. This would also explain why they didn't hesitate to upgrade to High risk on 4/2 despite models not looking super crazy the night before. 3/14 overnight outbreak, which easily verified as a high, and maybe 3/15 (not sure but probably) also featured a fast-moving jet streak, so no surprise that all three of those ended up being major outbreaks. I'd be interested in looking at past events and see what the jet translation speed for those were. I believe I saw somewhere that the May 6 High risk last year was around 30kts, which would make sense why that event underperformed.
As of now, Monday appears likely to meet the threshold for a high end tornado outbreak across the Day 3 Moderate area, so that's probably why they are aggressive with this forecast despite some lingering uncertainties/inconsistencies on models. Now of course that doesn't mean that we'll for sure see a High risk upgrade, but it's certainly possible.
I am in no way a professional. Take what I say with a grain of salt as I could be totally wrong. Please refer to the NHC, NWS, or SPC for official information.
Boomer Sooner!