FARGO — The outlook for the spring flood has changed little because of the lack of snowfall since mid-January, though the 5% chance here has nudged up to a Red River crest of 39.7 feet from 39.1 feet predicted in the outlook two weeks ago.
But the likelihood of more moisture — including a snowstorm expected to hit the Red River Valley Sunday, March 15, and Monday, March 16 — as well as a spring melt delayed by the return of cold weather mean the area still could face a top 10 or even a top five flood, the National Weather Service warned.
The weather service's latest spring flood outlook, released Thursday, March 12, includes a quarter inch to half inch of moisture that is expected to come from the snowstorm Sunday and Monday, with the heaviest amounts expected for the central to northern Red River Valley.
The range of probabilities in the new flood outlook gives a 10% chance of 38.2 feet, 25% chance of 36.1 feet, a 50% chance of 34.7 feet, a 75% chance of 33.3 feet, a 90% chance of 32.5 feet and a 95% chance of 32 feet.
A 39.7 foot crest would be on par with the 1997 flood, the second-highest on record, which was 39.72 feet. The 50%-risk flood, 34.7 feet, would approach last year's spring flood in Fargo, 35.03, the 10th highest on record.
In the previous flood outlook, issued Feb. 27, the weather service predicted Fargo had a 5% chance of fighting a 39.1 foot flood, which would tie the third-highest on record, a 10% chance of a 38.5-foot crest, a 25% chance of a 36.2 foot flood and a 50% chance of a 34.8-foot crest.
Over the next two weeks, "We are going to struggle to get above freezing most of that time," said Greg Gust, a weather service meteorologist. "We are now pushing our risk later and later in the season."
Forecast models indicate another possibility of snow March 19-20, with half an inch or more of moisture, he said. A quarter or half inch of moisture is normal now to April, so if precipitation stays at that level, the flood risk could be kept in the 50% range, he said, which would be similar in Fargo to last year's spring flood.
Because of the lack of significant snow since mid-January, Fargo's precipitation available for the spring flood has slid down the rankings. From Sept. 1 through March 10, Fargo received 11.73 inches of moisture. That compares to 15.19 inches in 2009, which produced the record flood with a crest of 40.84 feet.
Still, Gust said, there has been little risk reduction since the initial flood outlook, released Jan. 23. Wet soils and high river and stream levels persist, with the water content in the snow cover remaining "at or above normal," with high runoff potential.
"Really the flood risk hasn't changed much," he said. "Still little additional snow since mid-January, but stay tuned. One is coming."
That means the risk for significant snow-melt flooding continues to be substantial, running above long-term averages across the Red River and Devils Lake Basins, Gust said.
Fargo city officials are preparing to fight a possible 39-foot flood. That would require building 8 miles of levees in 22 sites with about 10 locations that would require sandbag protection.