Conditions as of: February 16, 2017
Next Update: March 2, 2017
This spring flood and water resource outlook is for the Rapid City Hydrologic Service Area (HSA) which covers northeastern Wyoming and western South Dakota. The main river basins include the Little Missouri, Eastern Powder, Belle Fourche, Grand, Moreau, Cheyenne, Bad, White and Keyapaha River Basins.
To obtain the latest watches, warnings, statements, and advisories, go to: http://weather.gov/unr
Flood Outlook Summary
At this time, the probability of spring flooding from March through June is:
- Below average in the Little Missouri, Belle Fourche, and upper Cheyenne River basins due to dry conditions last fall.
- Near average in the Grand, Moreau, Bad, and lower Cheyenne River basins due to ample snowpack over the winter months.
- Above average in the White River basin due to saturated soil conditions and above average precipitation over the winter.
For the Black Hills and higher elevations, flooding from snowmelt typically begins in late April and May. Flooding on the plains due to snowmelt and ice jams typically occurs between February and May.
The potential for rainfall-induced flash flooding is not quantifiable because this type of flooding is usually caused by localized thunderstorms during the spring and summer.
The flood potential is still very dependent on weather conditions from now until the spring melt. The amount of additional snow and rain, the timing and rate of the spring thaw, and the timing of peak flows will have a significant effect on the flooding.
Since October 1 2016 precipitation has varied from below average across most of northeastern Wyoming and portions of far western South Dakota to above average across central South Dakota.