How to add a new responsive Layout for large viewports to Omega Theme
You need to copy the grids variable from the default alpha.info file, and add your new layout in your theme's .info file like so:

grids[alpha_default][name] = Default (960px)
grids[alpha_default][layouts][fluid] = Fluid
grids[alpha_default][layouts][narrow] = Narrow
grids[alpha_default][layouts][normal] = Normal
grids[alpha_default][layouts][wide] = Wide
grids[alpha_default][layouts][wider] = Wider  &lt;- Your custom layout
grids[alpha_default][columns][12] = 12 Columns
grids[alpha_default][columns][16] = 16 Columns
grids[alpha_default][columns][24] = 24 Columns

# Default settings for the new layout
settings[alpha_layouts_alpha_default_wider_responsive] = '1'
settings[alpha_layouts_alpha_default_wider_media] = 'media query here'
settings[alpha_layouts_alpha_default_wider_weight] = '4'


You'll also need a new CSS file (called THEMENAME-alpha-default-wider.css) to manage CSS for that layout, but Alpha/Omega should handle the rest for you.