How To: Create contour lines from an ASCII file in ArcGIS Pro
An ASCII (.asc) formatted text file representing raster data consists of header information, such as the number of columns and rows, coordinates of the lower left corner of the lower left cell, cell size of the raster, etc., describing the values of each cell in the file.
It is not possible to open an ASCII file directly in ArcGIS Pro. The file must first be converted to a raster dataset, and the Contour tool must be used to create contour lines.
The instructions provided describe how to create contour lines from the ASCII file in ArcGIS Pro.
Use the ASCII to Raster tool to convert the ASCII file to raster.