There's a greater than 50 percent chance of the Red River exceeding major flood stage at Grand Forks, Fargo and several other cities in the valley for the third year in a row, the National Weather Service announced.
But warning coordination meteorologist Greg Gust said the 2011 spring flood outlook released Thursday also contains "pretty sobering numbers" for the Devils Lake Basin, including a 50 percent chance the lake will break its record level by about 2.5 feet.
Gust said the weather service ran several "what-if" scenarios this fall to get a sense of what the lake might do next year. At first, officials set the computer models to assume the Devils Lake Basin would get normal amounts of rain and snow throughout the fall and winter and also have a normal spring thaw.
But even this conservative assumption showed high chances for setting a new record next year -- troubling news for Devils Lake, which has risen by about 30 feet in the past 17 years and reached 1,452.1 feet this summer.
"And even with that, just a normal condition, we were pushing up above 1,453 feet toward 1,453.5 feet," he said. "Now that we've already exceeded normal and are going beyond that with the precipitation, it's pretty sobering to start looking at 1,454 feet and higher as viable numbers."
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The weather service will release flood outlooks each month, updating the probabilities of spring flooding based on the latest weather conditions.
Devils Lake
Above-average snowfall has blanketed the region, especially in the southern Red River Valley, which has 15 to 20 inches of snow. In Grand Forks and other northern valley communities, the snow pack is 8 to 15 inches.
But parts of the Devils Lake Basin have as much as 40 inches of snow right now -- equivalent to 3 to 6 inches of water.
"We've already seen in the Devils Lake Basin that we've reached a full winter's worth of snow and are now exceeding it," Gust said.
Mike Lukes, weather service hydrologist in Grand Forks, said the lake is now at 1,451.5 feet, down less than a foot from the summer record because of evaporation and operation of an outlet.
But with so much snow set to melt next spring, the latest forecast shows that Devils Lake almost certainly will hit a new record in 2011.
The flood outlook, which is valid through September, gets its numbers by combining current weather conditions, snow depth and ground moisture and then running the figures through what happened each spring in the previous 60 years.
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The outlook calls for a 90 percent chance of the lake reaching 1,453.6 feet at Creel Bay; a 50 percent chance of reaching 1,454.6 feet, about 2.5 feet higher than the record set this summer; and a 10 percent chance of exceeding 1,455.9 feet.
Lukes said it's "no surprise" considering the deep snow pack and wet conditions surrounding the lake. Still, he said the outlook shows that, at least for now, "we expect to see no relief for Devils Lake."
Lukes said that even in the 1 percent outlook -- a "very risky" number to forecast because it's among the most unlikely of scenarios that will happen next year -- Devils Lake is still projected to rise to a point that's about a foot below a level that would cause a natural and uncontrollable spill out of connecting Stump Lake into the Sheyenne River.
Red River Valley
When it comes to flooding in the Red River Valley, Gust said there are three factors that each typically complete one-third of the "spring puzzle."
It's still "way too early" to accurately forecast the spring thawing conditions, he said, but the climate outlook calls for below-normal temperatures and normal to slightly above-normal snowfall for the rest of the winter.
But Gust said the other two factors "have us somewhat apprehensive" and could have more of an impact on flooding this year.
River flows throughout the region are at or near record levels for this time of year, including the Red River at Grand Forks, and much of the summer and fall moisture was still in the ground going into this winter's freeze up.
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"The trouble is they're very high, way too high for this time of the year now," he said. "So, they are more significant factors."
That also holds true for the snow pack this year, Gust said. Taking those factors into account, Thursday's outlook called for high chances of major flooding on the Red River next spring.
Grand Forks has a 56 percent chance of reaching major flood stage (46 feet) and an 88 percent chance of reaching moderate flood stage (40 feet).
Fargo has a 58 percent chance of seeing a major flood (30 feet) and an 85 percent chance of the Red River reaching moderate flood stage (25 feet).
Several other communities on the North Dakota side of the river face high chances of major flooding, including Wahpeton (37 percent), Drayton (51 percent) and Pembina (51 percent).
Oslo, Minn., has a 58 percent chance of reaching major flood stage (36 feet) and a better than 98 percent chance of reaching moderate flood stage (30 feet). But the outlook calls for only a 14 percent chance the Red Lake River at Crookston will exceed 25 feet, the major flood stage.
Gust said officials expect most of the region won't see record-breaking snowfall totals this winter. Even Devils Lake, which is far above the average amount of snow for this time of year, probably won't approach the snow record set during the 1996-97 winter.
He said most of the region's snowfall in recent years has been far below that record-setting winter -- yet there was major spring flooding up and down the Red River Valley in 2009 and again earlier this year.
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That's because of a persistent wet cycle, Gust said, and there's been "excessive precipitation" throughout 2010.
Fargo is just shy of 30 inches for the year -- 10 inches above normal -- while Grand Forks has seen about 27 inches of precipitation this year, about 7 inches above normal and slightly below the record 29 inches that fell in 1944.
"These basins are made to push a certain amount of water through in a given year," Gust said. "If you throw a foot above normal rain into them, they just cannot get rid of it in one year."
Reach Johnson at (701) 780-1105; (800) 477-6572, ext. 105; or send e-mail to rjohnson@gfherald.com .
