Interpretation:
The total precipitation of each month was compared to the normal monthly
total precipitation for each month.
A value of "0" means the month precipitation total was normal.
A negative value indicates below (drier than) normal and a positive value
indicates above (wetter than) normal for the specific month.

There were 143 months during the January 1998 through November 2009 time period.
84 Months were drier than normal
58 Months were wetter than normal
1 month was exactly normal