If you would like to know what is the unit rate, you can calculate this using the following steps:
13 inches ... 5 hours
x inches = ? ... 1 hour
13 * 1 = 5 * x
13 = 5 * x /5
x = 13/5
x = 2 3/5 inches
Result: There will be 2 3/5 inches of snow in 1 hour.