Severe weather threat for New Year’s Eve

We're a day early, but some of these storms in north Louisiana have been rotating today.


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Early morning CAM update:

The HRRR and the NAM have two slightly different solutions, with the HRRR bringing a cluster of storms through around mid afternoon ahead of the best dynamics but allowing more daytime heating. Basically it rides a cluster of storms in with a warm front (you can see it looking at dew points) and would be the typical that they fire approaching I12 and probably would be more likely severe as they move into southern Mississippi. Then a decaying thin squall line comes through with the actual cold front at night. 





See where the 65+s are near the state line vs the near 60s around Jackson? The storms ride that line in roughly. 



This is for the Northshore just ahead of that cluster of warm sector storms. Note, it gets into the 70s, which drives the instability high enough to get storming. If the temps don't make the 70s, like the NAM shows keeping things in the 60s, this early pop off might not materialize. There is tornado potential with the SRH and plenty of shear, but the deeper SRH isn't eye popping and the low level instability isn't as pronounced as you'd "want" for tornadoes. There is some wind potential here though with the strong winds aloft where the dry air is, any storms that can fire up that high would end up pulling some of that down. 

The NAM is less aggressive with the warm sector, just having a small cluster fire off near Baton Rouge and not really approach anything severe looking until up in Mississippi. 




The NAM here is a lot stronger with the low level SRH #s, with a ton of twist from the surface to 850 mb. There isn't much of a low level jet here though, and a little inversion around 900 mb doesn't scream explosive convection. Only instability here is pretty elevated. See the surface temperature? If this wind profile is in place and the temp can get up to like 72-73, then this might be a little more dangerous but as shown, probably pretty mild for our area. 

On the NAM, it's the squall line with the most punch. This makes sense if it has the temperatures correct, because the airmass will need some frontal forcing to really accelerate upward. Embedded within the line you'd see bowing segments and quick spin ups, mostly around and west of I49 but getting farther east into Mississippi. Basically following the enhanced area pretty well. The line begins to break up coming into the BR area. This would also put what I would think would be the best tornado potential over near Lake Charles in SWLA. 

The short version? We're going to watch the surface temperatures and check in on the SPC site to see where the 850 mb jet, CAPE, and SRH levels are showing up. Warmer at the surface? I'd expect storms to fire earlier and that to be the main severe risk as a cluster running S to N. Stays cooler and it'll mean farther west will see greater impacts because it'll have the best dynamic support with instability pretty limited. 

That's where I'd focus today, if I was crazy enough to chase QLCS naders in the jungle.

Does The SPC have designated times that they update, like The NHC? Or do they update when the need arises with severe WX events?