The models have progged a very interesting setup during the day on Tuesday in the Northern Plains. The 0Z NAM along with the 0Z GFS are forecasting the development of strong surface low pressure systems just off the High Plains. The NAM and the GFS are still differing on the position of the low pressure systems, but the NAM is forecasting a low pressure of 993mb to be situated in SW Nebraska at 0Z Wednesday. The GFS model is forecasting a low that isn't as strong, the 997mb low pressure system to be centered in W Kansas at 0Z Wednesday. However, the models agree on what could be a major storm system that is aimed to strike the Northern Plains on Tuesday. Looking at the areas of highest Theta-E Advection, northeastern Nebraska and southeastern South Dakota are in both of the models sights for highest chances of severe weather. Both models are forecasting a very moist atmosphere in both eastern parts of South Dakota and Nebraska with dewpoints running into the lower to mid 70's. Extreme instability is expected in the area, with SBCAPE values running higher than 4500 J/Kg via the 0Z NAM in southeastern South Dakota. Though storm relative helicity will be higher to the north, anywhere in this area can expect to see supercellular storms develop. However, a capping inversion (via the NAM model) will be in place for most of the day in South Dakota/Nebraska as 850mb temperatures are forecasted to be near 23-25 degrees celsius and 700mb temperatures are forecasted to be around 10-12 degrees celsius, but the GFS model is forecasting a weaker cap. This appears to be a make or break day for the northern Plains States, but is absolutely something worth watching.
Edit: 12Z NAM is showing a deepening low pressure, now progged at 990mb centered around the borders of Colorado/Nebraska/Kansas. NAM is still forecasting a very strong capping inversion over Nebraska which might hinder the chances of initiation across the state, even maybe hindering chances in SD along and south of I-90. Some turning in the winds is also noticed in SD, with surface winds to the South, 850mb to the S or to the E, depending on location, and 500mb to the SW. So far, I would consider EC/NC/NE South Dakota as a potential target.
Graphic for this forecast at "My Chase Forecasts" link below.