Snowstorms raise flood risks in Red River Valley
GRAND FORKS, N.D. — Thanks to recent snowstorms and blizzards, the risk of spring flooding has increased significantly in parts of the Red River Valley, especially in the south, according to the National Weather Service’s latest outlook.
Still, rivers are not expected to approach record levels unless spring is unusually wet, which currently is not in the forecast.
It will be “nowhere to the levels of 2009, 2010 or 201l,” said Greg Gust, warning coordination meteorologist with the agency’s Grand Forks office. “On a positive note, the drought impacts are easing slightly.”
The Red River in Fargo, N.D., now has a 79 percent chance of major flooding. The risk was just 6 to 7 percent last month. The Grand Forks area has small chance of major flooding, but the risks rises farther north on the Red, especially in Oslo, Minn., and Pembina, N.D.
Devils Lake could rise by 1.5 to 2 feet, considering precipitation, runoff through two outlets and evaporation, and ultimately end the summer at about 1,451.4 above sea level, virtually the same elevation it is today. That’s about 3 feet lower than the record set in 2011.
Because of wide variations in snowpack and snow-water measurements taken from the ground and air, the weather service said there is some uncertainty in the flood risks.
“It’s too close for comfort,” Gust said.
Partner agencies and volunteer networks “will be out in full force” from late this month through early March to fill in existing data gaps, the agency said.
The weather service released its spring flood outlook Thursday. The next outlook will be issued March 7.
Chance of flood
The term “major flooding” does not mean a major flood fight. Rather, it is a level that triggers local officials to take precautionary measures.
“It may not be noticeable to the casual viewer,” Gust said.
-- In Fargo, major flood stage on the Red River is 30 feet. There’s a 50 percent chance the river will reach 33.2 feet, a 25 percent chance of 35.1 feet, and a 5 percent chance of 37.8 feet, the outlook said. The record is 40.84 feet, set in 2009.
-- In Grand Forks, the chance of reaching major flood stage at 46 feet is only 6 percent. The record is 54.35 feet, set in 1997.
-- In Oslo, the chance of reaching major flood stage at 36 feet is 19 percent. The record is 45.55 feet, set in 1997.
-- In Pembina, the chance of reaching major flood stage at 49 feet is 40 percent. The record is 54.94 feet, set in 1997.
-- To the far south in Wahpeton, N.D., the chance of reaching major flood stage at 14 feet is 64 percent. The record is 19.42 feet, set in 1997.
The weather service based its outlook on a variety of factors.
Late January and February snowstorms and blizzards added significant amounts of snow and snow-water across eastern North Dakota and western Minnesota, especially in the southern Red River Basin, the agency said.
Snow depths measure up to 2 feet in the headwaters of the basin from southeastern North Dakota into Minnesota lakes country; 6 to 10 inches across east-central North Dakota and the west-central Minnesota part of the basin; and 10 to 20 inches in the rest of the basin, the outlook said.
The deeper snowpack contains upwards of 5 inches of water, while the shallower snowpack contains 1 to 2 inches and the rest of the basin holds about 2 to 4 inches. Snowpack in the southern valley ranges from 3 to 5 inches.
While the Red River Valley remains in a severe drought, which has persisted over the past 15 months, the recent snowfall has improved conditions, according Gust.
Deep soils remain quite dry and stream flows are low, he said, “but topsoils did get wet last fall and are frozen, so significant runoff is expected.”
The climate outlook is for temperatures to trend from normal to slightly cool, he said, and precipitation to range from normal to slightly wet.
-- Kevin Bonham, Forum News Service
-- Kevin Bonham, Forum News Service