21Z 19 APR 2017 Surface Plot with boundaries
21Z 19 APR 2017 NWS Surface Analysis (source: NWS)
The surface divergencce and vorticity chart adds an extra element to your analysis. Recalling that a boundary is characterized by convergence and a cyclonic wind shift, you can use the convergence areas (in red) and positive vorticity areas (shaded green) to help identify boundary locations.
The boundary that stands out is the cold front that extends from Omaha, NE into southwest KS, and then northwest into CO. There is a well-defined wind shift along the boundary and colder air to the north. The accompanhying warm front that extends from Omaha eastward across southern IA is also well-defined by a cyclonic wind shift and temperature gradient.
A weak trough extend northward from Omaha into western IA. Winds to the east of the trough flow from the east while winds to the west of the trough are northerly.
The dryline from southwest KS into west TX is a little more challenging. There is weak convergence in the TX and OK panhandles with lower dewpoints to the west. The location of the dryline has been placed along the 45 degree isodrosotherm, the traditional location of the dryline.