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Severe WX Severe Weather Threat 3/14-3/16

A series of posts from Andrew Shearer regarding Saturday. Seems relevant since a lot of us are talking about limiting factors, floors and ceilings. I'll quote the text since Twitter gives me all kinds of headaches when trying to link lately.
1/ Now I have time, I can provide my thoughts on a potentially volatile severe setup on Saturday. I will go over what is known well, and some lingering uncertainties that remain for this setup. 2/ There's pretty good agreement on the synoptic trough, location of surface features, moisture, instability, and shear in place. In short, the overlap of parameters favorable for severe weather (particularly tornadoes) is a very rare combination of upper echelon. 3/ The ceiling for this event is potentially one of the highest in recent memory. However, the floor now is also particularly high given recent guidance. In my opinion, the latest guidance shows limited failure modes, and those failure modes would only prevent higher coverage. 4/ However, the main limitation is the extent of morning convection as ensembles suggest high chances of morning convection throughout the 12-18z period. CAMs, however, show a mixed bag at this time. This could be a parameterization issue, but something to watch. 5/ Another limitation to consider is the strength of the EML present. Models like the NAM/NAM 3k show a particularly strong EML while other models show a weaker EML overall. That is a known bias of the NAM, which explains its high instability. 6/ The EML is also important for more open warm sector convection. As the NAM 3k has a stronger EML, it has less prefrontal convection. This is a known bias of the NAM/NAM 3k, and most other models show a weaker version of the EML. This is something else to watch. 7/ Overall, most discussion should be over how widespread this severe event will be as it has the chance to be a widespread outbreak of severe weather, including tornadoes. However, these lingering uncertainties are also important when forecasting this event.
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Clancy said:
A series of posts from Andrew Shearer regarding Saturday. Seems relevant since a lot of us are talking about limiting factors, floors and ceilings. I'll quote the text since Twitter gives me all kinds of headaches when trying to link lately.

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So, the EML is the ballgame?
 
Fred Gossage said:
At least for Saturday, the mid-level air from the MS/AL/TN warm sector isn't coming from Oklahoma. It's coming from the northern Mexican plateau. But an EML is needed for a significant tornado event, and a slightly stronger cap than what is face value modeled in the CAMs at the current moment. They are trending in the direction they need to, however.
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Interesting insight Fred. What factors do you look for to try and ascertain what the “optimal” cap strength needs to be?
 
On his videos, James Spann talks about weather anxiety being a real medical condition. I know we all love the weather on this message board. However, don’t be afraid to step away for a few hours and do something else. As much as I love the weather, I think I need to take a break this evening from this thread to protect my mental health and do something else and come back tomorrow afternoon. Even then I might need to pace myself so I don’t get too overwhelmed as this system will be a long duration event.
 
Regardless of smoke impacts, CAMs are showing a concerning trend of moderate to high CAPE values as far north as Minnesota tomorrow...

Hard to believe we were discussing moisture return 24 hours ago, this system now has the potential of a widespread tornado outbreak from Minnesota to Georgia over the course of two days. Kinematics in Iowa/IL are already forecast to be upper-end. Thrown in 1500+ CAPE and strong to even violent tornadoes are possible.
 
Extent of morning convection is really a thing we aren't great at knowing in advance until it's going on, so that might be a factor we will not be able to nail down until Saturday morning; by that point mesoscale features become the main thing to watch
 
I’ve seen the term OWS now a few times, what exactly does it mean?
 
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