Flooding from spring snowmelt runoff can be a temporally isolated episode. Ironically, Red River flooding which occurred in 1989, did so in the midst of a prolonged and intense dry period as shown by the annual data. Another interesting feature of the December through March data is the lack of winter totals less than two inches since 1986-1987. Figure 4 depicts October through April precipitation totals. This sequence of months was chosen in an effort to capture autumn soil moisture recharge, winter precipitation, and the April precipitation that often compounds snowmelt runoff flood events.
Temporal variability is again quite obvious.
Note that the 1996-1997 total is the largest value on record. Figure 5 summarizes May through September precipitation totals, the bulk of the growing season. On average, two thirds of annual Red River basin precipitation falls during these five months. Interannual variability is again quite obvious. As was the case with annual precipitation patterns, a distinct drying is obvious for the first four decades of the 20th century.