RSS FeedsHydrologic Summary for May 2002 for the Area Served by the NWS Forecast Office at Sioux Falls, SD
Summary
There was no river flooding in the area during May. However, there were two flash flood events resulting from "training" thunderstorms which redeveloped and moved across the same areas.
Flooding
The first flash flood event in May occurred in east-central South Dakota into southwestern Minnesota on the 8th and 9th. Average rainfall of 4 to 6 inches fell in these areas, with maximum amounts of 8 to 10 inches. Kingsbury, Brookings, Lincoln, and Lyon counties were affected by this flooding. Flooding farm fields was the main problem reported in these areas, but there were a few roads that were also flooded. No estimate on monetary damages was available at this time, and no injuries had been reported.
The second event was on the Perry Creek basin north of Sioux City on the 28th and 29th. Average rainfall of 2 to 4 inches with maximum amounts of 5 to 7 inches fell across the basin with this event. Union, Dakota, Woodbury, and Plymouth counties all received flash flooding during this event. The Sioux City metro area experienced significant urban flooding with many roads and intersections under water, requiring the rescue of several motorists. Other county roads were also inundated and closed for a period of time as Perry Creek overflowed. There were no reports of injuries, and no estimate on monetary damages was available at this time.
General Hydrologic Information
Temperatures in May were below to much below normal across the region. Most areas recorded average monthly temperatures 3 to 4 ½ degrees below normal. Precipitation for the month was generally 1 ½ to 3 inches. This is 1 to 2 inches below normal. Some isolated monthly totals of 5 to 10 inches were recorded in areas that received flash flooding. Some places in the far western areas only received around 1 inch of rain for the month, which is around 2 ½ inches below normal.
Stream flows at the end of May were near normal to slightly above normal for all but the extreme western areas, where below normal stream flows were observed. The long term drought indices show near normal to slightly dry conditions. Soil moisture is slightly below normal across the region, but dry conditions have not persisted long enough to cause any water supply or agricultural problems yet. Precipitation totals through the summer months will be crucial for the abnormally dry conditions to either improve or deteriorate into a drought.
June 4, 2002
