By Brian Gehring
Barring heavy snow or rainstorms in the coming months, the National Weather Service in Bismarck says the risk for spring flooding for most of the region is below average.
The weather service issued its latest spring flooding forecast Thursday, good through late May.
Patrick Ayd, a meteorologist with the weather service, said the exceptions in the Bismarck area are for the Cannonball River at Breien and Apple Creek east of Bismarck.
Ayd said those locations have an elevated chance for minor flooding not becauseof snowpack, but because of the deep frost depth in the soil.
Almost all of the region went into last fall with a more than ample amount of soil moisture. With the onset of winter, that translates into frozen soil – more than 4 feet deep in the Williston area.
A lack of snow cover has driven the frost lines unusually deep, Ayd said – 43 inches down in Bismarck and 53 inches in Williston.
“If we get an early rainstorm,” Ayd said, or heavy snows in March or April, “that’s going to be problematic.”
He said the outlook for the next three months calls for below-normal temperatures with an equal chance for above- or below-normal precipitation.
The average daytime high temperature in March is roughly 30 degrees, warming to about 45 by the end of the month.
For Apple Creek, Ayd said the forecast calls for a 68 percent chance of minor flooding compared to a historical chance of 57 percent.
The odds for moderate flooding on Apple Creek are 59 percent and 48 percent for major flooding. The flood stage for Apple Creek is 15 feet.
For the Cannonball River, Ayd said there is an 81 percent of minor flooding, mainly because the flood stage at the Breien gauge is just 10 feet.
The chance for moderate to major flooding on the Cannonball drops to around 5 percent, mainly because of a lack of snow.
“West of the Missouri River doesn’t have a lot of snow cover,” he said.
In terms of the potential for ice jams on the Missouri, Ayd said that remains the wild card in the equation, especially after the 2011 flood.
Ayd said while there is quite a bit of open water on the river now, there is a chance for ice jams to develop, particularly in the oxbow area near the University of Mary.
The flood of 2011 deposited large amounts of silt in that area of the river.
“The potential is always there,” Ayd said. “It’s difficult to predict.”
Releases from the Garrison Dam through the next three weeks call for 18,000 cubic feet per second through the end of the month, then a drop to 16,000 cfs through mid-March.
Ayd said higher releases can be both beneficial and detrimental in terms of ice jams.
High releases can eat away at the ice from below, opening up water, or can cause flooding in the event of ice jams.
Ayd said those along the river should call their local emergency manager or law enforcement agency to report rising water.
The weather service said the Souris River upstream of Minot and the Des Lacs River are generally at a near normal risk of minor flooding this year.
Frost levels in the soil are deep there as well, Ayd said, and the highest probability of flooding is in the Towner and Bantry areas.
On Thursday, Sen. John Hoeven, R-N.D., and Gov. Jack Dalrymple issued a joint statement calling for continued improvements in the management and operations of the Souris River.
The Souris River is jointly managed by the United States and Canada through the International Joint Commission’s International Souris River Board.
“It’s important that we move forward on a full study of the Souris River’s management and operations,” Dalrymple said in the statement.
“A plan of study offers us a great opportunity to learn more from the devastating flood of 2011 and is key to developing effective, long-term flood protection throughout the Souris River Basin.”