Next two days look to be coming together well and will focus on these days in the discussion here as a few long days on the road have me tired. First looking at the 500 mb flow for tomorrow afternoon there is some more appreciable flow come into the central/high planes with the main center of vorticity just west of the 4 Corners region. Not ideal but can still make for enough large scale ascent to get some cyclogenisis going. The 500 mb chart below shows better flow over the westerns portion of SD but what has my eye is the KS/NE border region:

The reason why the KS/NE border region has my attention has to do with the surface features setting up in the region. The surface chart below shows surface winds and moisture. We can see that the wind shift along the KS/NE border is indicative of a warm front setting up and there is a dryline bulge in the extreme NW corner of NE. These two regions of lift along with the backing sfc winds and increasing 850 LLJ pushing into the evening hours have me hopeful that there could be some storm development. Capping may be issue as well but forcing looks to be sufficient to overcome it late in the day. I will point out that the GFS is in the same general ballpark as the NAM, see second image.

Assessing the the 4 km NAM precipitation model clearly the KS/NE border region looks to break out but the western SD region does as well, likely in response to the stronger flow aloft. I have m doubts that moisture will make it that far north and storms may not pack the punch the 4km NAM seems to show. I am also keeping an eye on storms that may fire near the Ogallala, NE region as well, which look to fire along the dryline. There is no real evidence of a good push east of the dry line here thus these do have me wondering as well. But based on the analysis setting up in Valentine, NE to keep southern SD in play (near Mission) and southern, NE in play and keeping with the favoured target near the dryline/warm front intersect seems like a good compromise for now. Other factors influencing this are CAPE values of 2000-2500 J/kg possible and sfc-500mb bulk shear of 30-40 kt. Timing is a little late as per the forecast below but the 20-23 UTC time frame will likely see storms going.

Looking at Saturday May 15, I’m going to analyze the NAM very briefly. The reason why is mostly because I don’t agree with where the GFS is placing the surface low. Given that the base of the 500 mb trough is digging down into TX with stronger divergence over the west KS region, I feel that cyclogenisis near the CO/KA border is the more likely scenario, which is also supported by the latest SREF and 12Z ECMWF. See the first image below. The GFS and GEM seem to favour a most elongated area of low pressure with the main low center into northern SD. This is a little concerning but I think that the NAM solution has the right idea.

That being said then there are several targets likely for this scenario. Along the warm front through NE and into SD, the triple point in northeastern CO and northwestern KA, and along the dryline from Colby to Dodge City, KS. Given the leading edge of the southern 500 mb jet is pushing into the Colby region and that region sits between the right entrance of the northern branch of the 250 mb jet and the left exit of the southern branch. I’m going to target the Colby, KS region for as a tentative target for now.