Historic Red River Crests at Fargo-Moorhead During April.
Spring snowmelt run-off flooding typically reaches its peak along the Red River near the Fargo-Moorhead area from mid-March into mid-April. A secondary crest may also occur later in the growing season due to runoff from summertime rains.
The probabilistic outlooks prepared on March 24th, 2011, are based on the basin conditions present at this time, run against the temperature and precipitation regimes which occurred during historic flood scenarios in the past 60 or so years. Of those years, the 29 years depicted below represent floods which occurred between March 27th and April 30th.
Clearly the next three weeks are crucial, as 9 of the 11 major spring floods since 1948 have occurred in this period (2009, 2006, 2001, 1997, 1989, 1979, 1978, 1969, 1965). Major floods in 1966 and in 2010 occurred the preceding week in March. Major floods in 1975 and 2007 occurred long after the main snowmelt runoff period, in late spring or early summer.
Climate indicators and the historical record suggest an enhanced risk for a rapid warm-up beyond the first week in April, 2011, with an increased risk for above normal precipitation during the mid-month period.