Why Nebraska?

All of these ingredients will conveniently find themselves in a single location tomorrow afternoon...

• Nose of upper level jet
• strong diffluence 
• strong curvature from downstream ridge amplification over the course of the last 18 hours
• More than sufficient instability
• synoptic flow will keep morning warm frontal convection cirrus and debris from hampering afternoon destabilization
• Strong cyclogenesis
• bulging dryline and cold front
• pressure falls in region (Dima I know you like that parameter)
• Excellent vertical speed shear (ie bulk shear)
• lowest 1.5 km speed shear of 30 knots
• SSE wind at surface and SW at 850 (ie helicity)
• further enhanced shear from LLJ hour or two before sunset when storms are still coupled with BL

And this...