This is my first time using this dataset, so I have probably made an elementary mistake. I am having trouble understanding a file from the NCDC's climate normal dataset:

http://www1.ncdc.noaa.gov/pub/data/normals/1981-2010/products/precipitation/ann-snwd-avgnds-ge010wi.txt

Here is a sample of a few rows from the above file:

USC00064767 105P

USC00065077 31P

USC00065445 370S

USC00069388 66S

From the documentation:

ann-snwd-avgnds-ge010wi.txt Long-term averages of number of days during the year with snow depth >= 10 inches

From the readme and the above, I am assuming that the numerical portions of the entries in the second column in the above sample should all be numbers of days per year, so at most 367.

Any ideas for me, or other places to look? Did I miss any threads on this forum that discuss how idiots can understand NCDC data?