Severe Weather Thread - 6/17/26 - 6/18/26

[WeathermanLeprechaun]

Right. I know SPC hasn't outlined a area and you can call this premature if you want, i understand if so. But I think there's been enough trends on ensembles and enough consistency on deterministics to pull this. Many runs have shown a high end, anomalous parameter space for portions of Missouri into Illinois (go figure, it's 2026) and haven't really backed down on this threat at all.

I expect SPC to pull a 15% sometime tomorrow. Because I'm not sure that this cold front on Monday will big time affect this event. Maybe less instability than modeled but for the worth the kinematics are there. Uncertainty remains but this is what you're dealing with. Sounding taken from W MO around the LLJ peak. Maybe 2026 goes again with its classic red herrings, but maybe we go again next week. Remains to be seen. Watch this closely.

 

[Kds86z]

If it’s Illinois, it’s gonna happen! Lol

 

[Brice W]

I know it’s 2026. But this looks like some of your bigger outbreaks synoptically, I know I know, I’ve said it before, but you can ignore that trough and 75 dew points. That’s all I’ll say for now.

 

[Cyclonic Paracosm]

I've seen some stuff and whew the paramspace is wild for the 17th been hella consistent

 

[Cyclonic Paracosm]

00 European Model with a gnarly profile SPC needs to add at least a 15% next outlook cycle which is in 2hrs if I remember correctly

 

[Cyclonic Paracosm]

Mention uncertaintys and higher-probs may be needed

 

[WeathermanLeprechaun]

Dare to say it, but Wednesday could easily be the most volatile parameter space of the year, the way things are looking. A 30% contour next outlook is easily possible.

 

[WeathermanLeprechaun]

The analogs on this sounding speak for themselves..Just a insane parameter space modeled here.

 

[N0mz]

Just like Thursday, when an April-esque trough shows up in mid June, you should pay attention.

 

[Kds86z]

 

[Kds86z]

 

[Grand Poo Bah]

Pretty crazy for a day 5 CSU run

 

[Ozonelayer]

Yeah uh, Wednesday looks very volitile. April-esque trough and great synoptics mixed with June thermodynamics. Yeesh

 

[Brice W]

Very early but Wednesday looks ugly. Not calling anything a lock this far out, but for it being far out, this is the most volatile modeled environment we’ve seen so far this year.

 

[N0mz]

Should we extend this thread to the 18th as well? Also outlined on the d4-8

 

[N0mz]

Buckle up. 30% added for Wednesday across N MO and central IL, 15% maintained for Thursday across the mid-Atlantic.

 

[N0mz]

Writeups I did for New England:

Stormnet ringing bells for us Thursday. For those unaware, Stormnet is a new AI tool for SVWX forecasting that came out this year and has performed exceptionally well. Green is about equivalent to an SPC slight or enhanced, so this is quite a strong signal for d5. I know some may hesitate due to relatively modest forecast EMLs, but globals tend to underestimate thermos, and with the forecast shear (60-70+ EBWD and 300+ 3k SRH), I wouldn't want to count anything out. We await the king NAM.

and Mid Atlantic:

Since I'm back home in Boston, I've mostly been following our weather, but I wanted to stop by here. Obviously, insanely potent jet for this time of year, with 100+ kt on Wednesday over the Midwest and nearly 100kt as it takes on a negative tilt on Thursday over NE, both per 00z euro. The GooFuS solution favors you all with the trough swinging down a little bit more and overspreading the region with 40-50kt flow, which is good for this time of year. It should be noted that with these super-fast (speed and translation) punching jets, you don't need to be right in the centroid to see good storms. Deep-layer shear should be pretty good due to the strength of the jet, although it remains to be seen whether the LLJ and associated SRH will reach down to MA. Attached is a model sounding at BWI at 18z from the 00z GFS. 41 EBWD supportive of supercells, but, as you can see, it's mostly speed shear with no real turning with height due to a very modest 850mb jet. CAPE is skinny on this sounding in particular, but I wouldn't worry, as many others were 1000-1500+, and globals tend to underestimate thermos anyways. We will have to wait for the SVWX king, the NAM, to bring us the goods.

over on americanwx

 

[N0mz]

Also, ASTORP introduced a small 15# over KC for Wednesday:

 

[WeathermanLeprechaun]

Safe to say, a potentially dangerous day with strong to intense tornadoes in Central MO. GFS suggests discrete development in a dangerous kinematic environment. Further east, I'm having doubts about how much CAPE arrives for IL/IN.

 

[WeathermanLeprechaun]

Should we extend this thread to the 18th as well? Also outlined on the d4-8

Done. Euro runs have been interesting in this area..