The above image is a departure from normal barchart for a particular county for the last 365 days.
Along the X-axis are the time intervals for the precipitation computations. From left to right, each time interval increases by 30 days or roughly one month starting with the last 30 days on the left side of the graph.
Bargraphs are drawn in red above each time interval denoting the percent of normal for the corresponding period. Above each barchart are two numbers separated by a dashed line. The top number is the observed areal precipitation for the county as computed by MARFC. The bottom number is the normal precipitation as derived from the National Climatic Data Center data sets. The percent of normal is computed by dividing the actual by the observed and multiplying by 100.
Along the Y-axis are the percent of normal tick marks.
The horizontal green line is tied to the 100% normal tick mark on the Y-axis. Bargraphs below the 100% line indicate a period where precipitation was below normal. Bargraphs above the 100% line indicate a period where precipitation was above normal.
Below the graph is the graph's supporting data in tabular form.