NWS ups moderate flood risks

Recent snow storms have increased the chance of minor to moderate flooding along the Red River, the National Weather Service announced Thursday.

Minor flooding is almost certain throughout the main stem of the Red River, including Fargo, Grand Forks, Drayton and Pembina, all in North Dakota, and Oslo, Minn.

"It's better that we had this precipitation," said Mark Ewens, climate forecaster for the weather service in Grand Forks. "I've heard from a lot of farmers recently who said they'd sure like to see some snow cover."

"Even in the south, where they got a lot of snow, it's been dry," he said. "This isn't cause for concern. It's good news."

Two storms during the last week in February added from an inch to 1¼ inch of snow-water to the southern third of the basin, and from ¼ to ¾ inches of snow-water to the northern two-thirds of the basin, according to the latest report from the weather service in Grand Forks.

Oslo is among the areas with the highest chance of moderate flooding, pegged at 88 percent. That's up from 25 percent in mid-February.

The chances of moderate flooding through the rest of the Red River Valley include: 58 percent in Fargo; 19 percent in Halstad, Minn.; 41 percent in Grand Forks; 45 percent in Drayton; and 50 percent in Pembina.

Flood risks

The risk of major flooding at those points is: 19 percent in Fargo, up from 6 percent in mid-February; 4 percent in Halstad; 6 percent in Grand Forks, up from 3 percent; and 8 percent in Oslo, up from 4 percent.

Along tributaries, there's a 9 percent chance of major flooding in Grafton, N.D., and 8 percent in Neche, N.D.

Meanwhile, the latest spring outlook for the Devils Lake Basin remains virtually unchanged from the last one, with a 20 percent chance that the lake will surpass an elevation of 1,454.3 feet above sea level this year.

The lake reached a record 1,454.4 feet in June 2011, but since has dropped to about 1,453.4 feet.

The chances of minor flooding along the Red River are: 98 percent in Fargo; 51 percent in Halstad, Minn.; 93 percent in Grand Forks; 93 percent in Oslo; 77 percent in Drayton; and 67 percent in Pembina.

Still pretty dry

The weather service said the latest outlook was created before the second round of snowfall actually was measured.

If the actual snowfall and snow-water measurements vary significantly from estimates, or additional snow occurs in early March, an updated outlook will be issued later in the month, it said.

The outlook indicates March will be warmer and wetter than normal. The early indications are that April and May could be somewhat warmer than normal.

"In the grand scheme of things, it's dry," Ewens said, "but not like it would have been had we not received these recent snows. This will probably continue for the near future."

Weather service computer models do not extend three months in the future to accurately forecast temperatures and precipitation, however.

"We use history as a guide," Ewens said. That history shows winters such as this past one are followed by a string of months with oscillating weather patterns in which, for example, a warm, dry month is followed by a colder, wetter month, then another warm month, etc.

What's next

Below is a summary of the National Weather Service outlook for the Red River Valley and Devils Lake:

• Snowpack has resurged with the last snow storm of February, with depths of nearly 18 inches in the Bemidji area, extending toward Detroit Lakes and Park Rapids, Minn. Less than 15 inches appear in the Devils Lake and Upper Sheyenne River basins. Lesser amounts appear in other regions, including only 4 to 6 inches found in Cavalier County in North Dakota and Kittson and Roseau counties in Minnesota.

• Snow water content is relatively normal with this snow, with 2 to 3 inches where the snowpack is deeper and 1 to 2 inches elsewhere.

• The top few inches of soil remain somewhat dry, but are completely snow-covered and quite frozen, while deeper soil levels appear damp but not saturated at freeze-up and have remained so. Soils are frozen from 20 to 40 inches over most of the area, as a lack of snow cover early in the winter allowed frost to penetrate more deeply than last year.

• Most rivers and streams remain ice-covered, with levels and flows still somewhat above normal for this time of the year, but well below record levels of the past two winter seasons.

• Factors yet to be determined are the growth of the snowpack, the rate of snowmelt/thaw; and the possibility of heavy rain on top of snow or frozen ground during thaw or peak flood season.

• The short-term weather forecast calls for near normal temperatures, with light dustings of snow through the weekend, followed by near normal to warmer-than-normal temperatures with little chance for precipitation until mid-March.

• The updated climate outlook for the remainder of March indicates an increased risk for above-normal precipitation and an increased risk for above-normal temperatures, with above-normal temperatures continuing through April and May.

The next scheduled spring flood outlook will be issued March 22, unless conditions require an earlier update, according to weather service.

To learn more, check out the National Weather Service's flood potential outlook . The first few pages are the Red River Valley outlook. Click through several pages to see the Devils Lake outlook.

Reach Bonham at (701) 780-1110; (800) 477-6572, ext. 110; or send email to kbonham@gfherald.com .