NWS Rapid City, SD - Spring Flood and Water Resource Outlook

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

Updated: March 7, 2013
Next Update: As needed during Spring 2013

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 significant flooding from snowmelt is low. However, heavy snow later in the spring could increase the chance of snowmelt flooding.

The potential for ice jam flooding on rivers and streams is below average. Several small streams and creeks have dried up due to drought conditions. Although most rivers are ice covered, low water levels would not produce much flooding if ice jams develop when temperatures increase.

The potential for rainfall-induced flash flooding is not quantifiable as this type of flooding is usually caused by localized thunderstorms during the spring and summer.

Conditions as of March 7, 2013

Snowpack is limited to the higher elevations in the Black Hills and Bear Lodge Mountains. Snow cover at lower elevations is minimal, at best. Most rivers and streams remain ice covered. On the larger lakes, the ice thickness is between 2 and 10 inches with quite a bit of open water. Lakes in the Black Hills at higher elevations are reporting ice thickness of 10 to 20 inches.

Precipitation

Precipitation so far this winter (since October 1, 2012) has been below average across the entire area.
Precipitation in January was above average in portions of northeastern Wyoming, the Black Hills, and southwestern South Dakota. Across northwestern South Dakota, precipitation was below average. However, average January precipitation is only between a quarter and a half inch on the plains, with amounts slightly over an inch for the higher elevations in the Black Hills and Bear Lodge Mountains.
In February, precipitation was below average except in south central South Dakota and in the Bear Lodge Mountains where precipitation was above average.
So far in March, precipitation has been below average except for the Bear Lodge Mountains where precipitation has been around average.

Click here for preliminary monthly precipitation amounts for northeastern Wyoming and western South Dakota.

Central Plains Departure from Normal Precipitation since October 1	Wyoming Percent of Normal Precipitation	South Dakota Percent of Normal Precipitation

Monthly Percent of Normal Precipitation from the High Plains Climate Center

Snow Cover and Liquid Water Content

The majority of the snow cover is limited to the higher elevations of the Black Hills and Bear Lodge Mountains. Snow cover at lower elevations is minimal.

Snow Depth	Snow Water Equivalent

Modeled Snow Analyses from National Operational Hydrologic Remote Sensing Center

Cole Canyon	North Rapid Creek	Blind Park

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

Soil Conditions and Frost Depths

Soil moisture is below average according to the latest calculated values produced by the Climate Prediction Center. The latest values can be found at: http://www.cpc.ncep.noaa.gov/soilmst/index_jh.html. Frost depth values are minimal, with most lower elevations reporting less than six inches of frost in the ground.

Lake and River Conditions

All river basins in the area are reporting normal streamflows.

Current Reservoir Data from the Bureau of Reclamation
Angostura Reservoir	Belle Fourche Reservoir	Deerfield Reservoir


Keyhole Reservoir	Pactola Reservoir	Shadehill Reservoir

Precipitation and Temperature Outlook

Climate Prediction Center Temperature and Precipitation Outlooks

According to the Climate Prediction Center, the outlook for March indicates a greater chance of below average temperatures across northeastern Wyoming and northwestern South Dakota with equal chances of below average, above average, or average temperatures for the rest of the area. For precipitation, there are equal chances of average, above average and below average precipitation. For March, the average high temperature is in the middle 40s and the average low temperature is around 20 degrees. The average precipitation amount is around an inch on the plains with two and a half inches for the Black Hills and Bear Lodge Mountains.

March Temperature Outlook	March Precipitation Outlook

According to the Climate Prediction Center, the three month outlook covering March, April, and May indicates equal chances of average, below average, and above average temperature and precipitation.

Three Month Temperature Outlook (March, April, May)	Three Month Precipitation Outlook (March, April, May)

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

National Weather Service Weather Forecast Office