A fix was made to the RUC analysis on 7 March at 1300 UTC to prevent a divide-by-zero condition that was responsible for a crash on 12 Feb. It is possible that other occasional crashes were caused by this same condition. There is an ongoing log of NCEP RUC changes, including this fix, at http://ruc.fsl.noaa.gov/RUC2.changelog.html (also under the main RUC page in the index on the left).