Spring Flood and Water Resource Outlook for Western South Dakota and Northeastern Wyoming

Updated: March 28, 2014
Next Update: As needed during spring 2014
 

Spring Flood and Water Resource Outlook

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, Upper Missouri, White and Keyapaha River Basins.  

Current Flooding and Spring Flood Potential

To obtain the latest watches, warnings, statements, and advisories, go to: http://www.crh.noaa.gov/hazards/unr

At this time, the potential for flooding this spring is above average due to saturated soil conditions, lack of water storage availability, and higher than normal stream flows. However since there is limited snow cover right now, additional moisture is needed to cause this flooding.

  • For the Black Hills and higher elevations, flooding from snowmelt typically begins in April or 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 thaw, and the timing of peak flows will have a significant effect on the flooding.

Conditions as of March 28, 2014 

Current snowpack is confined mostly to the higher elevations in the Black Hills. Snow cover at the lower elevations is minimal. Soil moisture is above average and frost depth values are around two feet with the first foot or so thawed. The frozen and saturated soil conditions increase the likelihood of flooding this spring.

Precipitation

Since October 1, 2013 precipitation has been above average, especially since October was extremely wet. Runoff from the October blizzard and large rainstorms that followed, saturated the soil and filled stock ponds. This moisture froze into the ground during the winter and has left very little room for snowmelt and rain runoff this spring. 
Click here for preliminary monthly precipitation amounts for northeastern Wyoming and western South Dakota.

Central Plains
Percent of Normal Precipitation since October 1

Wyoming
Departure from Normal Precipitation

South Dakota
Departure from Normal Precipitation

Image of Percent of Normal Precipitation for the Water Year

Current Climate Summary Map

Current Climate Summary Map

Monthly Percent of Normal Precipitation from the High Plains Climate Center

Snow Cover and Liquid Water Content

Current snowpack is confined to the higher elevations of the Black Hills and Bear Lodge Mountains. Snow cover at lower elevations is minimal.

Snow Depth

Snow Water Equivalent

Thumbnail image of Snow Depth

Thumbnail image of Snow Water Equivalent

Modeled Snow Analyses from National Operational Hydrologic Remote Sensing Center

Cole Canyon

North Rapid Creek

Blind Park

NRCS Snotel Graphic for Cole Canyon

NRCS Snotel Graphic for North Rapid Creek

NRCS Snotel Graphic for Blind Park

Black Hills and Bear Lodge Mountain Snotel Data from the Natural Resources Conservation Service

Soil Conditions and Frost Depths

Soil moisture is above average according to the latest calculated values produced by the Climate Prediction Center. The frost is beginning to come out of the ground at the lower elevations on the plains with the ground still frozen in the Black Hills and Bear Lodge Mountains.  The Ground typically thaws by the end of March into early April on the plains and toward the end of April into May for the higher elevations. The frozen and saturated soil conditions increase the likelihood of flooding this spring. 

Calculated Soil Moisture Anomaly

Modeled Snow Moisture from Climate Prediction Center

 Lake and River Conditions

All river basins in the area are reporting normal to much above normal streamflows.

Monthly-Average Streamflow

Streamflow Mapping provided by the USGS

Current Reservoir Data from the Bureau of Reclamation

The graphs below denote reservoir storage levels. The line labeled active is the point where the reservoir is considered "full" which is when the pool elevation is at the top of the active conservation pool. Most reservoirs have additional storage above this level for surplus or to hold flood waters.

Angostura Reservoir

Belle Fourche Reservoir

Deerfield Reservoir

Current Reservoir Data for Angostura Reservoir

Current Reservoir Data for Belle Fourche Reservoir

Current Reservoir Data for Deerfield Reservoir

 

Keyhole Reservoir

Pactola Reservoir

Shadehill Reservoir

Current Reservoir Data for Keyhole Reservoir

Current Reservoir Data for Pactola Reservoir

Current Reservoir Data for Shadehill Reservoir

Precipitation and Temperature Outlook

Climate Prediction Center Temperature and Precipitation Outlooks

8 - 14 Day Temperature Outlook

8 - 14 Day Precipitation Outlook

According to the Climate Prediction Center, the outlook for April indicates a greater chance for below average temperatures with equal chances of below average, above average, or average precipitation. For April, the average high temperature is in the upper 50s and the average low temperature is around 30 degrees. The average precipitation amount is around two inches on the plains with three and a half inches for the Black Hills and Bear Lodge Mountains.

April Temperature Outlook

April Precipitation Outlook

Monthly Temperature Outlook

Monthly Precipitation Outlook

According to the Climate Prediction Center, the three month outlook covering April, May, and June indicates a greater chance for below average temperatures with equal chances of average, below average, and above average precipitation.

Three Month Temperature Outlook
(April, May, June)

Three Month Precipitation Outlook
(April, May, June)

Three Monthly Temperature Outlook

Three Monthly Precipitation Outlook

Questions or Comments

If you have any questions or comments about this spring flood and water resource outlook please contact,

Melissa Smith
Service Hydrologist
National Weather Service
300 East Signal Drive
Rapid City South Dakota 57701
Telephone 605-341-9271
E-mail
melissa.smith@noaa.gov 

 

 


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