There are now clear observations of large parallel electric fields (E$parallel$) from Polar and FAST in the auroral upward-current region (UCR). Such fields in some events are associated with large perpendicular electric fields (E$perp$) and density cavities while in others they could occur without them. The observed features of the fields and density are found to be compatible with the spatial structures seen in a simulated U-shaped potential structure (PS) using a 2.5D electrostatic code. The spatial and temporal evolution of the U-shaped PS (USPS) including its upward and downward motions and its striations into thin long potential structures suggest a variety of signatures in the satellite detection of E$parallel$ and E$perp$.