Need to count repeating, consecutive values in python dataframe within a groupby

Question

df = pd.DataFrame({\'site\':[1,1,1,1,1,1,1,1,1,1],\'parm\':[8,8,8,8,8,9,9,9,9,9],\'date\':[1,2,3,4,5,1,2,3,4,5],\'obs\':[1,1,2,3,3,3,5,5,6,6]})