Rapid Snowmelt Accelerates Red River Flooding

Published April 28, 2013

| AccuWeather

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-years 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.

The Red River at Grand Forks was at 35.41 feet early Sunday morning, or about 7.41 feet above flood stage. The river will continue to rise to near 45 feet, or 17 feet above flood stage by Thursday night, May 3rd.

Farther to the south, the Red River at Fargo was at 27.85 feet early Sunday morning, or 9.85 feet above flood stage. The river will continue to rise to near 38 feet by Wednesday night, which is only 2.8 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.

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.

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.

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.

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 18th.

Other recent significant floods occurred along the Red River in March 2010, April 2006, April 2001, April 1999 and April 1996.

URL

http://www.foxnews.com/weather/2013/04/28/rapid-snowmelt-accelerates-red-river-flooding/