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2026-04-14 EVENT: IA, IL, WI, MO, KS, OK, TX

Joined
Jul 16, 2025
Messages
46
Location
Madison, WI
For the upper Midwest on Tuesday, there's a lot of potential but also a lot of questions. Models have been unusually inconsistent about where and when things might happen. However, they've consistently shown plenty of storm ingredients, and storms initiating somewhere, so that's got me watching the day carefully.

Models forecast a moist airmass in place with lots of CAPE (models are often showing 3,000-4000+ J/kg across a significant area) and significant mid-level lapse rates. There's a healthy 500mb jet, with strong low-level winds often producing enlarged hodographs.

Models put a dryline in the ballpark of west Iowa, with a warm front/occluded front east of that. Both would be places to watch for storm initiation, and some model runs include warm-sector storms.

However, models have varied markedly on where they put these ingredients, and whether they put storms within those places (before dark). Other potential downsides include there being clouds earlier in the day and weak low-level lapse rates, as well as enough moisture throughout all altitudes to have me thinking about high-precipitation storms (though I admit I don't know how much moisture triggers that).

My overall take is that Tuesday has a high ceiling, but with a lot of question marks. Still, though we don't yet have a good sense of the details, there's enough there that I'm currently optimistic that at least somewhere will get some very interesting weather.

I also note fast storm movements are often shown in the simulated soundings, on the order of 40-50 mph. This looks like a good day for chasers to be extra cautious: From the outlook now, I could picture a high-precipitation supercell moving at 50mph with a strong tornado hidden by rain.
 
There sure is a lot of unanswered questions for tomorrow, Tuesday. I see the outlook has been upgraded, and the ingredients appear to be favorable for a severe day in and around the Chicago area. With that being said, don’t really see too much agreement in the models as of yet. I think a lot is going to have to do with what happens today north of us, and if the Chicago metro area becomes involved in any of today’s action. Personally I think it is going to be mainly a large hail and destructive wind type of scenario, but gonna hold off on making a go or no go decision until later today or very early tomorrow morning.
 
I haven't looked at Tues 4/13 since this morning, but as of then multiple models showed the difference between the surface/850 mb and 300/500 mb level much improved (from a chasing point of view that is) near the dryline in NW TX into OK. The last few days (Sat 4/11, Sun 4/12, and what Mon 4/13 has looked like so far) the flow has been non-optimal over the southern plains dryline target. This sloshing dryline got a lot of people excited, but I kept seeing flow issues, and I could not hop on the band wagon. We will see what Tuesday am brings, but right now I think I will head out.
 
Models now are at least starting to look more similar to each other, even if they disagree how far east/west things will be. Possibility of undercutting cold air is a lot more present, though.
It’s looking like a bulge/in-cutting of the dryline somewhere in IA/WI/IL territory might be a focal point of good conditions and storm initiation.
 
Models that totally failed to initialize morning rain in Illinois surge the WF too far north into Wisc. Models that have the rain lift the WF more gradually, right into the SPC 10% hatched 2 zone. The reasoning is self-evident.

We're getting past the early season where one just forecasts the south end of the possibilities, but I'm not feeling the north end either. I'm thinkin' the WF in IL this am will make it to southern Wisc. Just not as far north as some early 00Z projections. Regardless of any model zig-zags (they always happen around 14Z) just follow that WF. I would slightly favor Wisc. Early Iowa storms could go tornado quickly; but, then you're trying to navigate a Mississippi River crossing. If chasing from Iowa, I suppose bag a tornado and be back in time for supper.
 
This morning, HRRR really wants south Wisconsin to have supercells, but other weather models are suggesting more toward central Iowa, at least for tornadoes before dark.
(That said, I didn't read Jeff's post until after writing this.)

Forecast soundings are often looking impressive (though not always); I continue to think that today has a high ceiling for what could happen.

With high CAPE, lapse rates, and wind shear, hail could also be a big-time threat, in addition to the tornado risk, which is what I'm most interested in.
 
We are starting to clear out in the Chicago metro area and having mostly sunny skies, have to see how warm it gets, and right now doesn’t feel too humid. Have a feeling it may get interesting here or a little further north between 3-10 pm.
 
Looks like there could be a couple of outflow boundary plays away from the main action areas. The background environment is supportive virtually anywhere that boundary can keep from washing out. HRRR has been all over the place, but as we saw yesterday, it's also been picking up on things that verified - just with not-great run-to-run consistency.
 
I can't say I have much confidence in a target location (beyond ballpark area), but at least storm motions are looking a little slower in the forecasts, and ENE to E motion is around the orientation of a lot of roads.
 
Dan beat the SPC to it. Yes outflow OFB is noted down in Illinois actually south of Chicagoland. OFB may lift closer to town which is sub-optimal for both the population and chasing. I also feel like it could use some higher probs.

Then the main WF is surging in Wisc. A couple weeks later and I'd favor the OFB to the south with building CAPE. Still mid-April I lean for the shear up on the WF. IIRC southern Wisconsin is not yet forest. A few supercells should get going long enough to chase before the whole thing blobs out.

As for the nowcast, just keep on whichever boundary one chooses. Follow it closely.
 
The Cu field along the I-72 corridor in IL has been very flat so far this afternoon, with little change in the past 2 hours. The upstream cirrus deck evidently indicates the incoming main wave impact is imminent, so we'll see if it can give the extra push to get a storm or two going. I'm not very optimistic at this point.
 
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