hlcater

Looking at medium to long-range ensembles, the signal for a potentially active pattern is really quite strong(especially given the range) and it's hard not to like what is being shown. First off, subtle system coming into the west next week will probably yield some chase worthy days with a potential lull for a few days over the weekend.By weeks 2/3 things really get interesting, the modeled jet extension starts to come into play here and this is where that super consistent -- both run to run and model to model -- signal is located. Northern hemispheric pattern is also following a rather textbook evolution that tends to lead towards active periods for plains severe wx potential and supports this evolution. The current ridge over the Yukon/Alaska slowly retrogrades with time and ultimately ends up somewhere over Eastern Siberia. Furthermore, a ridge looks to build to a limited degree over Hawaii, with multiple strong waves crossing the pacific on a track for the western US courtesy of an active jet. Looking like the long-range could evolve into a fairly active stretch and given the range there's really quite the signal for it. It also makes sense with AAM/GWO transition but the mechanisms of how AAM and tropical forcing mettle with patterns is not my cup of tea (though to be fair none of this hemispheric stuff really is). One last thing is that the AAM/GWO transition is not as amplified as last year which might mean that the resulting pattern is not as amplified (someone correct if wrong), and if that is the case, combined with an Actually Present EML™, could set up a really nice chasing period. I'm obviously very optimistic.However, one thing that does put me on hold here is the tendency for low latitude troughing to show up on some ensemble runs. The gulf is cooking this year so whether or not this actually has any significant effect with such a strong gulf and being in the second half of May remains to be seen, but it is there off and on and is worth noting.But for now, let's just treat ourselves with this. 18z GEFS pacific pattern gif just because:

Sleeper setup that could be alright if moisture/thermos are there. Nothing high end and there's a ton of uncertainty regarding convective evolution, but these tight surface lows kind of have a hot hand in 2020. I'll be keeping a half eye on it for potentially a local chase Tuesday.

In a raw 1v1, I'm inclined to agree, but the NAM goes against consensus here which is notable to me. It is very possible guidance trends in that direction(euro had a tick slower), but I don't see this reaching the levels the NAM thinks it will.

Looking like consensus is still sticking with a faster(rather than slower) evolution with this system keeping the ceiling much lower than it would be if it were to slow down significantly. Definitely still time for that, but seeing the 12z suite, I think the NAM is almost certainly the outlier on the slow end, GFS an outlier on the fast end.

Lots of variation in guidance. Unsurprisingly, the models that are more significant with the parameter space are also the ones that have the slowest progression (NAM/UKMET). Will have to watch to see if their solution becomes favored. As this had been modeled up until today, the surface low was lifting out far too quickly, leading to a veering of the LLJ/surface winds by midday thursday. The 12z UKMET is slightly more backed with each, while the 00z NAM is substantially more backed. This system will also be pulling some sort of an EML with it from the plains, so thermodynamics are pretty good on all models.

Just came across some of the worst tree damage I think I have ever seen. Supposedly from Bassville. Compare with Smithville: and El Reno '11

Never have I seen a couplet appear, ramp up like that (to 190mph G2G) and disappear as quickly as that one did. Knowing the area, there was almost certainly topographic influences at play.

Going to have to watch this mess of convection here to see if something can organize out of it and move into the PDS watch in S AL. The environment down that way is still incredibly conducive for long tracked tornadoes and supercells. It is in veered flow for the time being, but flow is more backed in MS/AL.

Couplet orientation relative to both the RFD and FFD suggest this is still an inflow dominant circulation and has not occluded yet. Remains to be seen how long this lasts. Could occlude in 5 minutes or 30, hard to tell.

Subjectively, given what we've seen so far and that picture, this tornado was almost certainly violent and at least a mile wide. It's been down for over 45 minutes now and for ~35 miles. Incredible situation unfolding

The debris scattering and fallout downshear of this tornado is by far and away the most expansive I have EVER seen. Wow.

its on Sharppy skew-ts. SPC meso has a 3CAPE/LLLR crossover plot thats really helpful too

Anymore, I find myself using 0-3km MLCAPE as my instability parameter of choice over SBCAPE, particularly with regard to tornadoes. I've found SBCAPE is best used as a discriminator as to how robust an updraft may be but not how "good" that instability is for tornadoes. That definitely applies here I think and the fact numerous models are struggling to surpass 50 3CAPE is something I find tough to ignore.

A met for the same NWS office was also saying that the low level moisture will take care of and somewhat compensate for subpar low level lapse rates. While this is certainly true to an extent, I tend to think that low level instability is far more the consequence of low level lapse rates than is on moisture and numerous setups in the past which depended on OWS thunderstorm development suffered for it (5/20 says hi). Furthermore, cold core events with their 50s dews and 7.5*C/km+ LLLRs are the absolute quintessential example of this. Despite the moisture quality being good here, I think if the low level lapse rates decide not to cooperate we may be out of luck and storms may struggle to become surface based in the warm sector.

Definitely worried about sloppy storm modes for this one. Models(particularly the UK) have somewhat improved here, but there continues to be a signal for widespread thunderstorm activity potentially as early as 12z. Ideally, I'd like to put some distance between the setup and the gulf, or otherwise put something over the gulf/gulf coast(like the right exit region or an EML or both!) to temper the amount of thunderstorm activity we have. I'm not entirely sure there's much that can be done about tstm activity north of the warm front, or that it particularly matters in this setup if it clears out in a timely fashion. I think the ceiling is super high here given the frankly excessive hodographs that are present on the UK/Euro, IF we can get supercells in that environment. Even if we cant, a parameter space like that has a tendency to just make tornadoes out of blobs of rain.

I think I'm the only one in here that wanted a part of that 2" hail around here earlier. So that's exactly what I did. Went and got cored near Springville to the company of multiple stones larger than golf ball size with a few exceeding 2". Then decided to set up on a hill and get a time lapse of the backside of the storms illuminated by the sunset. I'm no photographer so this is just about as good as sunset time lapses are gonna get for me. Warning: The first video is *loud*.

I’m still mad about that

Models as a whole have kind of abandoned this idea today. Now looks like its only gonna last 5-7 days before switching back to a more severe wx favorable base state.

This isnt gonna be linear off the pacific front. Discrete storm mode with splitting cells seems most likely to me personally right now. Look at nature of boundary, storm speeds and shear vectors.

Euro just popped a CA of 60. Quite a step up from previous runs and the NAM with CAs of 35-40.

I do think this setup has the potential to be pretty clean. Certainly cleaner than 11/17 ended up verifying as. This doesn't mean this setup is superior to 11/17(because it isnt) but as far as storms themselves go, I think they're gonna be more isolated. The only things I'm worried about from a setup perspective are the critical angles/linear hodographs(see below) and the fairly limited residence time storms will have on the axis of best parameters before flying out of the warm sector at light speed. Storms, especially those at the triple point, may only have 2 hours or so before they go stable. With all this being said, even some small modification to the 0-3km hodograph yields pretty big changes and a much higher caliber of a setup. Whether or not this can be successfully chased remains to be seen.

The NAM is actually the worst model in the suite right now. I think the globals(particularly the UK) are painting a better setup. The primary difference between them and the NAM is the fact that the NAM is significantly faster

Quite a signal coming in from the UKie. Has had something similar for 3 or 4 runs now.

Iowa has closed all schools for 4 weeks per Kim Reynolds.