2018-06-25 Event: KS/NE/MO/IA/IL

[Ben Holcomb]

A continuation of Sunday's event. Still a lot of question marks about overnight convection and some extremely warm (16-17C) 700mb temps during the day, but the GFS cools off between 18 and 00Z near Topeka and NE KS to acceptable levels (11-13C) and produces some fantastic hodographs on the nose of the LLJ (where has that been all season?!)

A couple things i don't like including a lagging surface low to the SW of where I'd expect supercells to fire, but if I'm chasing Saturday and Sunday I might as well try for Monday right? Definitely seems like a higher end probability day for 2018 which isn't saying much.

 

[chrisbray]

I also noticed on soundings I pulled that the winds above 500 seem really weak, but I agree the hodos looks great beyond that. The SPC seems really down on this day based on last night's out look, mentioning only MCS modes.

 

[Billy Faletti]

Tomorrow is certainly not a pretty colors day and has changed pretty dramatically from when this thread first started, but jet impulse moving over modestly unstable warm front laying across Iowa tomorrow may be a decent play. Yes, I know, Iowa. But 12z NAM solution paints CAPE values of 1000-2000 j/kg along the WNW-ESE oriented warm front, with impressive low level shear right along the front near I-80. Convective trends will certainly be a major factor in how everything plays out, but there may be some tornado potential if an optimal solution occurs.

I somewhat cherry picked a sounding along the warm front near Grinnell, IA. You can find several similar ones along the front between Des Moines and Iowa City. Wind profiles to the NW of Des Moines get messier but may still be workable. Lapse rates are not that impressive and again, instability is modest, but also note ample 0-3 km CAPE. VBV is also present in the upper levels, but this doesn't really concern me that much given how high up it is and the magnitude of low level shear.

This will almost certainly change somewhat between now and then, and may end up not happening, but it seems to be the only thing going for tomorrow at this point. Might be worth the gamble, especially for those eyeing out Tuesday's potential just to the east.

 

[Devin Pitts]

Thread header should probably get amended to have Iowa added.

Hodo's look pretty decent, the low level shear is there, plenty of moisture, and I'm a big fan of subtle warm fronts like what is being progged for tomorrow. Biggest question is the ongoing convection early day and how much clearing there will be near the warm front. Currently eyeballing that corridor between DMX and Iowa City as well, while potentially cheating a bit further east if it clears out better that way. Gonna be another day where I ignore models and glue my eyeballs to surface obs, haha.

 

[Andy Wehrle]

Not a fan of that large area of rain lifting into the threat area from the southwest.

 

[Dan Robinson]

Pretty legit tornado/supercell threat evolving just south of I-70 between STL and Jefferson City. E-W boundary favorably oriented for deviant motion, out cooking in the sun, 40kt+ of bulk shear and a gradient to a reservoir of 2,000-3,000 MLcape to the south, backed surface winds north of the boundary. Storm mode is the only potential negative I see with this situation, not to mention the terrible terrain and roads south of I-70 and rush hour traffic in the metro at storm time. Looking likely that the STL metro will see some significant winds even if storms don't stay discrete.