Rapid Snowmelt Accelerates Red River FloodingWarmer temps unlocked half-a-year's worth of water in winter snowpack
People walk on a narrow strip of land between the flooded Woodlawn Park, background, and the rising Red River, foreground, Sunday, April 28, 2013, in Moorhead. (AP Photo/The Forum, Dave Wallis)
Rapid snowmelt began in earnest on Saturday across the Red River basin. Temperatures across much of North Dakota and Minnesota reached well into the 60s, 70s and 80s, effectively unlocking nearly half-a-year's worth of water stored in lingering winter snowpack.
Snowmelt from April 20, 2013, to April 27, 2013, has been on the order of 10 to 20 inches across parts of the basin, with most of the melting occurring in only the latter two days.
This has resulted in what amounts to a two-day rainfall of 2.00 to as much as 8.00 inches, and rapid, dangerous rises on the Red River.
This map, courtesy of the National Operational Hydrologic Remote Sensing Center, shows how much water was trapped inside snowfall on April 20th.
The Red River at Grand Forks was at 37.33 feet Sunday afternoon, or about 9.33 feet above flood stage. The river will continue to rise to near 46 feet, or 18 feet above flood stage by Thursday night, May 3rd.
The Red River at Grand Forks will crest late next week at 45 feet.
Farther to the south, the Red River at Fargo was at 29.24 feet Sunday afternoon, or 11.24 feet above flood stage. The river will continue to rise to near 37 feet by Tuesday night, which is only 3.8 feet below the record of 40.8 feet.
Dangerous flooding of low-lying areas will be the first impacts, and this has already been seen across many areas along the river.
As the river continues to rise, the impacts will begin to pose more of a risk to life and property.
The Red River at Grand Forks on April 27, 2013, was swollen and filled with melting snow and ice. Photo by Matt Eckhoff, a graduate student and meteorologist at the University of North Dakota in Grand Forks.
According to the Associated Press, preparations have been underway to protect the cities of Fargo, N.D., and Moorhead, Minn., to a river level of 41 feet.
This includes sandbagging and ensuring that levees are in good shape. Temporary dikes will also need to be constructed during the coming days in order to protect the Hjemkomst Center.
Flood waters will force many roadways to close, and travel to the region by early to late next week is not advised.
The Red River at Fargo will crest next week around 37 feet.
Expert Senior Meteorologist Alex Sosnowski said earlier last week, "Spring flooding is not uncommon for the river which flows across a vast plain. There are no steep hillsides to contain the river. During a flooding event, when left unchecked, the river can stretch for hundreds of square miles beyond its banks."
Sosnowski went on to say, "The river also flows from south to north, from a warmer climate to a colder climate, which can amplify flooding in certain situations, such as from ice jams or heavy rain in one part combined with heavy snow in another."
This will be a prolonged flooding event. As hinted, the waters will not even crest until the middle or end of next week, and the waters will be very slow to come down, perhaps not receding below flood stage until the second or third week of May.
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Normally with late-season snowstorms, a thaw occurs in between. This allows the ground to warm up and absorb some of the melting snow.
However this season, the weather has remained very cold between the storms, so the ground has not thawed as it normally would at this point in April.
The frozen ground increases the runoff potential into the river system.
A look at the expected flood stages on the Red River for Monday.
Record flooding occurred in Fargo during 2009, when waters reached a level of 40.84 feet on March 28th. The 2009 flood was the fourth highest on record at Grand Forks, N.D., with a level of 49.33 feet on April 1st.
The most recent flood on the Red River occurred during the middle of April in 2011. At Grand Forks, waters crested at 49.33 feet. During this flood, the forth highest crest on record occurred at Fargo with a state record of 38.81 feet.
The record crest at Grand Forks was 54.35 feet during the April 22, 1997, flood. The 1997 flood brought the second highest crest on record at Fargo with 38.72 feet on April 18.
Other recent significant floods occurred along the Red River in March 2010, April 2006, April 2001, April 1999 and April 1996.
In addition to the melting snowpack, rain is on the way for the Red River Valley.
Rain will fall on part of the area later Monday into Tuesday, as a storm system moves into the northern Plains from the Canadian Rockies.
"Fortunately, not enough rain will fall from this particular system to greatly impact water levels on the Red River," Sosnowski said, "Since the bulk of the snow melt occurred without rainfall, crests on the river are likely to fall short of record levels."
"However, even with the lack of heavy rainfall, the level on the river will reach major flood stage at many locations, which will send water into unprotected areas," Sosnowski added.
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