hlcater

really cant help but think we see storms struggle to maintain supercell structure tomorrow, but I dont know of any analogous environments. just that effective shear and cloud layer shear are far below the threshold you'd expect. Don't think we go unpunished for that so to speak. That being said, 400 0-1km SRH and ~150 0-3km CAPE are probably good for something. Would probably be staring at a moderate risk if the profile above 500 wasn't worse than garbage.

Tomorrow’s setup in IL/IN is completely foreign to me and I honestly have no idea what to think of it. Especially the hodographs. 0-6km shear is nothing short of substantial and likely results in storm motions exceeding 40kts, but wind aloft is significantly backed and in much less magnitude. The result is a hodograph I’ve literally never seen before where it doubles back on itself. What the result of this is, perhaps rain on inflow? Similarly, never seen 0-6km shear contrast with abysmally low EBWD that is typically far too low to support supercells. To me, storm speed seems to suggest that this environment appears far more sheared than it actually is in a storm relative sense. If storms can initiate on a confluence zone in S IL or elsewhere, my guess is that we get fast moving clusters of storms and transient supercell structures with perhaps a few tornadoes owing to large SRH values present(note the sounding posted is on the conservative end of guidance) I’d feel better if EBWD and cloud layer shear weren’t in the gutter. Thermos should be sufficient but not stellar and shear aloft is better with northward extent tomorrow. Definitely interested to see what results from this.

This is easily going to be one of the worst storm chasing seasons of all time.

The storms a few nights ago dumped on me. Measured 1.98”.

This month is just about locked in for the worst May ever. Far cry from how things looked even 10 days ago. Tomorrow/Saturday could be decent but its not gonna save the month. It really is fascinating considering that the second half of May looked good as late as May 13th.

Can we just take a moment to appreciate the beauty of this?

In other news, tomorrow looks conditionally fun for some low topped supercell action and perhaps a few tornadoes assuming atmosphere sufficiently destabilizes. Environment is very similar to today's setup in the Arklatex and is reminiscent of classic low topped supercell days.

Finally getting around to it, but I also chased the HP supercell in Iowa last Thursday. I never did find my localized area of backed winds, but was bored and needed something to occupy my time so I went out anyways. Storm went up farther west than I thought it would, initiating all the way back by I35, when I was expecting initiation near Oskaloosa or Ottumwa. Arrived on the storm near Melcher Dallas and found it to be OD and sucking strong but cold inflow. This is just how this storm was, and never at any point while I was on it did I think it had any significant tornado potential. Chased it to near Washington, where I let it run over me and went back to catch some rainbow/sunset stuff. Core was far more intense than I was expecting it to be however, and I encountered what I would crudely estimate to be winds in excess of 75mph and some pea size hail. Fun local chase overall.

The NAMs show the type of environment I’m looking for with regards to tornadoes. Both have an area of localized backing in W IL with good thermos.

I would ideally like to see more surface backing tomorrow(to SSW or even due S) than is currently modeled if I were forecasting for tornadoes. Storm motion is also boundary parallel, but that doesn't seem like a variable that is likely to change. Lapse rates through 500mb per 18z runs are actually quite steep (all exceeding 7.0*C/km) and would support a damaging wind and potentially even a hail threat should any supercells evolve. I'll be out if it looks like any enhanced corridors of low level shear are likely to evolve. Looking pretty sloppy regardless.

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.