On SIGWX (significant weather) charts, what does **/** mean?
http://www.beyourowncaptain.com/downloads/files/Reading%20Prog%20Charts.pdf
http://aviationweather.gov/static/adds/docs/metars/wxSymbols_anno1.pdf

Asterisks are snow, dots are rain. The slash means a mixture of the two. 



The dot with an R under it is a substitution for the the thunderstorm symbol.



What you're looking at isn't a real SIGWX chart, it's a testing figure.