Snowmelt due to warming temperatures is predicted to result in a second river crest for South Dakota’s James, Vermilion and Big Sioux Rivers. And, more rainfall is predicted according to the March 21, 2019 National Oceanic Atmospheric Administration’s (NOAA) April Climate Outlook.
“This is not the outlook that many wanted to hear,” said Laura Edwards, SDSU Extension State Climatologist. “The risk of major flooding is not over. Now is the time to act.”
Hydrologists and emergency managers strongly recommend state’s residents take flood preparation seriously. The state has activated its Emergency Operations Center in Pierre, with state and federal agencies in close communication.
And, the flood risk is not isolated to eastern South Dakota. The White River is already in moderate-to-major flood stage. Anticipated snow runoff is predicted to impact the Grand and Moreau Rivers similar to the upper James and Big Sioux Rivers.
Edwards encourages South Dakotans to follow the National Weather Service for most up-to-date weather and river forecasts and check out the SDSU Extension website where staff are posting daily updates to the site’s Flood Page, at extension.sdstate.edu.
Across the state, Edwards said snowpack is above average for this time of year, resulting in increased potential for more flooding. “Moderate to major flooding was already predicted to occur this spring for many of the state’s rivers. And, with much of the northern areas still waiting on their snow to melt, and a forecast of wetter than average conditions, South Dakota could experience accelerated snowmelt that will potentially increase runoff into rivers.”
Although warmer, more seasonal temperatures moved into the area the week of March 18, Edwards said the outlook predicts cooler temperatures to return at the end of March and into the first part of April.
“This pattern may hold throughout April, according to the NOAA Climate Prediction Center, as cooler than average temperatures are slightly more likely in April for the eastern two-thirds of the state,” Edwards said.
For many of the state’s farmers, this is unwelcome news.
“Cool and wet conditions will slow down spring planting, as the soil will be slow to dry after recent flooding,” Edwards said.
Resulting muddy conditions are also a concern for livestock producers. “Mud will continue to be a concern,” Edwards said. “The soil will also be slow to warm in preparation for planting.”
As of March 21, frost depths are close to 2-feet in southeastern South Dakota and as much as 4 to 5-feet in the north.
“Farmers may need to work quickly when conditions improve to plant their spring crops such as spring wheat, corn and soybeans,” Edwards said.
The NOAA National Weather Service predicts snowmelt will cause rivers to crest the week of March 25 through the first weeks of April.
“The estimate peak and timing are due solely to snowmelt,” Edwards explained.
There is an estimated 2 to 4- inches of water in the snow pack in north central and northeastern South Dakota. “If there is any significant rain, that will change the timing and peak flow through these rivers,” she said.
As of March 22, Edwards said the forecasted month-end crest along the Big Sioux from Brookings and southward, and the lower James River, may rank among the top five highest historically.
River levels could be close to past peaks in 1993, 2010, 1984 and even record levels in some reaches of these rivers.
Additional Resources:
For river levels and forecast information: https://water.weather.gov/ahps/index.php
For weather forecasts, flood watches and warnings: https://www.weather.gov/
For road closures and travel advisories: https://www.safetravelusa.com/sd/ or SDDOT 511 app or call 511.
