andyhb

Zack, I hope you're chasing tomorrow (or at least working at the office), could be a pretty significant event.

Pretty decently sized ENH risk/30% hatched for tomorrow nearly centered on the Twin Cities. 12z WRF-ARW/NMMB were pretty bullish with a few supercells across that area in the late afternoon, perhaps tracking near the warm front and its enhanced low level SRH.

More like Lieowa.

I'd definitely be chasing ND on Friday if I was out there. Moderate WSW flow aloft with strong instability and a well developed southerly LLJ feeding low 70s dewpoints into the area on both the GFS and NAM. Seems a couple of impulses ejecting ahead of the main upper low could provide enough forcing for ascent for CI.

Look out near AMA: http://www.spc.noaa.gov/products/md/md0900.html

That southern stream wave ejecting this upcoming Tuesday bears watching for the southern Plains and perhaps one last kick at the can for the chasers there. The last three runs of the Euro have shown a setup that looks conducive to tornadic supercells in KS and N OK with a moderate LLJ and a respectable, sub-1000 mb surface low along with 40-50 kt 500 mb flow (the latest run also increased the instability). I am really a fan of these kinds of lower amplitude waves that tend to not force major height rises to the east and create conditions favorable for VBV profiles. The GFS is faster and less favorable, although it appears to be a progressive outlier among the full suite and even its ensemble mean to some degree.

If we get at least a piece of this ejecting into a typical June warm sector, yowza.

Couple of strong LEWPs and a nasty MCV in that MCS moving across S LA right now.

4/10-11/2001. High risk on 4/11 for IL/IA, fairly prolific tornado outbreak in the Plains/Middle-Upper MS Valley.

Well, there goes the Monday system on all four model runs tonight.

If that Euro run slows 6-12 hrs and the 144 frame turns out to be more around peak heating, can't ask for much more than a potent negatively tilted shortwave with a 60+ kt southwesterly/west-southwesterly H5 jet and H85-H7 flow of 40-50+ kts this time of year.

It's convectively contaminated.

Eh, this run of the Euro wasn't so favorable. Trough gets more blocked in the west and the waves tend to shear out as they eject eastward. Need the larger scale trough to make it further east on its initial amplification.

Last four runs of the Euro (and three runs of the EPS) suggest a more progressive pattern in the mid range than the GFS/GEFS with that large upper trough amplifying in the W later this upcoming week then ejecting eastward (or at least pieces of it) by 5/22-5/24 and really amplifying the flow fields across the Plains. Might be quite the start to many chasecations (including possibly mine) if it turns out to be more on the right track. Would like to see more multi-model consensus on this less blocked idea though.

Seems like most of the models aside from the GFS want to eject a lead southern stream wave that basically screws the setup by stealing away the LLJ from the second trough (i.e. Monday's system) and shunts moisture southward.

12z GFS is basically suggesting a potential outbreak over a large area of the central/S Plains on Monday. Thing that really gets my attention is how broad the LLJ axis is, with 40-50 kt H85 flow covering much of OK, KS and N TX ahead of the dryline. The low amplitude nature of the shortwave trough was another red flag. Looked at some soundings basically from I-20 north to I-70 and my eyes just about popped out of my head. Euro isn't as enthused, showing a more disjointed trough ejection with weaker wind fields overall, but still plenty of CAPE. Finding it interesting that 5/9 produces majorly (anniversary of last year's CO, KS and Cisco tornadoes) and now 5/16 may try to do it as well (Elmer).

While it could obviously screw things up like the wind fields, I'm less inclined to believe it portends a lack of moisture return, especially into the High Plains. We've reached the time of year now where any sliver of the Gulf open to poleward advection for at least a day means there likely will be sufficient BL moisture. If this was March, obviously it would be an exercise in futility.

50 kt LLJ over ICT on the 00z Euro at 00z Wed, shear seems to be ramping up here in the last runs. Not to mention there's already 2000-3000 J/kg SBCAPE at 12z Tuesday across a significant portion of OK and KS.

I'd argue that the 12z Euro was more impressive than this GFS run (stronger LLJ, stronger flow overlapping the dryline, etc.) Maybe not quite as strong in terms of buoyancy, but still easily >3000 J/kg pooled up against the boundary. The upper jet orientation with this is classic as it looks right now, there's really no meridional concerns with the low amplitude nature of the low latitude ridging out ahead.

There's probably a moderate cap in place until initiation, which is exactly what you need to get supercells vs. a big linear mess.

That low level inversion is not realistic (happens time and time again with the GFS), and it's likely cooling the boundary layer too fast.

So if you get rid of that unrealistic decoupling of the boundary layer like the GFS always does at 00z, not much else to say but holy smokes. Depth of the BL moisture could be a bit better on the OK sounding, but man those wind profiles are basically textbook.

Looks pretty favorable as well, although it was further south for Tuesday last night (closer to the Red River Valley).

Popping 6/24/03, 5/3/99 and 4/26/91 in SARS on the same sounding? Not bad.

Tuesday next week is looking like a pretty legit threat at this point for somewhere in the Plains. Seeing some pretty top-tier instability/moisture values for late April, which makes sense with that lead shortwave this weekend assisting with poleward moisture transport. Oddly, it's falling directly on the 25th anniversary of 4/26/91.