I have also found inaccuracies in his script. For example, if the tag TSNO is present (which means (T)hunder(S)torm info (NO)t available his code interprets it to mean that there ARE thunderstorm conditions.
Also, his code seems to pay no attention at all to precipitation strength, he throws away the indicator before processing. (He has a comment about "getting rid of those annoying" hyphens and removes them with a string replace. Those "annoying" hyphens indicate the strength of the precipitation. A Hyphen means light, none means moderate, and a plus means heavy. He doesn't seem to realize that. ;)
A cribsheet for METAR format can be found
I have found difference between your program and Phpweather (http://freshmeat.net/projects/phpweather) about the height of the clouds, and temperature in °F.
An open, cross-platform journaling program.
A scientific plotting package.