2024-07-01 EVENT: NE/KS/SD/IA

[Dan Robinson]

The NAM and GFS are showing an impressive environment in a narrow zone between a warm front and dryline bulge in central to eastern Nebraska on Monday, July 1. Forcing aloft is shown as nebulous, but at least 30kt+ flow should be in progress over this area for much of the afternoon/evening. Midlevel lapse rates are shown weakening substantially through the evening, but both models show robust simulated reflectivity indicative of a storm in an environment with 70F+ surface dewpoints and large low-level hodographs. The width of the warm sector is a concern, and the GFS is less enthusiastic about the degree of instability. I'm not able to chase this one, but will be watching it evolve from afar.

 

[Brett Roberts]

This setup has intrigued me for several days now. The large-scale pattern with a low-amplitude but very broad W CONUS trough resembles some memorable central Plains days in late June. As more NWP guidance becomes available today, it appears the big wildcard will be morning convection. The NAM shows a worst-case scenario with extensive convection exploding around sunrise Monday over a large swath of KS/NE, after which the warm sector struggles to recover even to I-80 by early evening. That could very well lead to a cap bust. Global models have trended slightly in this direction over the past couple days, but still generally don't look nearly that bad, with a window of opportunity perhaps a couple counties either side of I-80 in C to E NE by 22-23z.

If the effective warm front can advance northward quickly enough to provide for a quality warm sector by late afternoon, this setup looks to have a reasonably high ceiling, IMO. However, poor mid-level lapse rates may be a secondary concern, even given warm sector storms. Otherwise, parameters and environmental attributes look impressive. And unlike the E NE event on 15 June (which still managed to produce a couple decent tornadoes), deep-layer shear should be more than sufficient for a late season, high CAPE setup.

 

[JamesCaruso]

Surprised there hasn’t been more activity on this thread. I considered a quick hit trip for this, figuring it should be a slow week at work and easy enough to take the day off. But I had family over yesterday, and would have had to fly out this morning. The bar would have to be super high to justify trying to fly and chase on the same day, and today doesn’t qualify. But if I were out there, I’d be setting a preliminary target of Holdredge, adjusting from there with the warm front. I think as Brett said there’s a high ceiling on this. I have some capping concerns, but I also don’t see 70s dews getting into the region based in current obs and surface wind trajectories. Mid-level shear is weak. The moisture and instability axis is also fairly narrow from a north/south perspective, so I could envision storms moving out of the best environment. Also LCLs are could be high south of the front.

I’ll enjoy some armchair chasing later today, and may check out some livestreams too. BTW - As part of my armchair chasing, I looked at flight status this morning and saw that three different originating flights for one-stop itineraries to Omaha were cancelled, and a 9am direct flight to Denver is delayed until after 11, not arriving until 1:30 MDT. I’d be going berserk if I was at the airport. Just goes to show why it’s futile to try flying and chasing in the same day, or bothering to fly out at all for one or two day chase trips. This is all on American Airlines, which is the predominant carrier out of Philadelphia.