From the home page click your state on the map or the name of your state below the map. On the next page click radar/lightning as your map type.
From the homepage on the national radar, select the layers option and select Lightening as a weather layer option.
Alternative, you can choose the Radar or Satellite links below the national radar from the homepage or from the navigation menu. Select the layers option on the radar and select Lightening as a weather layer option.