Low risk of significant spring flooding in Red River Valley, forecasters say
The magnitude of spring flooding likely will hinge on how much late-winter snowfall the region gets as well as the timing of the spring thaw.
FARGO — The risk of significant spring flooding is “relatively low” and lags behind long-term historical averages across the Red River Valley, according to an early outlook from the National Weather Service.
The outlook issued on Thursday, Jan. 26, the first of several reports to provide a look ahead at the spring flooding situation, predicts minor to moderate flooding.
Soil moisture levels were below normal and stream flows near normal before freeze-up, according to Amanda Lee, a hydrologist for the National Weather Service.
January has been mostly dry, but early-season storms contributed to above-normal snowfall and precipitation so far.
The climate outlook predicts a shift to a colder, wetter weather pattern that will prevail into spring, with much colder conditions and light precipitation expected over the next two weeks, including the storm expected to sweep the area late Thursday and Friday.
The magnitude of the spring flood will depend largely on two key factors: late-winter snowfall and the timing — whether abrupt or gradual — of the thaw cycle, according to the flood outlook.
Conditions are driest in the lower Sheyenne basin and southern Red River Valley, where precipitation is 3 to 4 inches below normal.
Elsewhere, moisture was 1 to 2 inches below normal.
The frost depth is near normal, although depths vary widely. The deepest frost levels, 20 to 30 inches, were recorded in northeastern North Dakota, with depths running 10 to 20 inches elsewhere.
Since Dec. 1, snowfall is running 125% to 300% of normal, with the highest amounts in the Devils Lake and Sheyenne basins. Water content in the snow ranges from 1 to 5 inches across the Red River Basin.
Expected Red River flood crests, according to the weather service’s initial spring flood outlook:
- Fargo: a 95% chance of reaching 19.1 feet, 75% chance for 21.5 feet, 50% likelihood of 24.5 feet, 10% chance of 34 feet and 5% chance of 36.2 feet. In Fargo, minor flooding starts at 18 feet, moderate flooding at 25 feet and major flooding at 30 feet.
- Grand Forks: a 95% chance of reaching 22.3 feet, 75% chance of 27.6 feet, 50% likelihood of 35 feet, 10% chance of 42.7 feet and 5% chance of 47.5 feet. In Grand Forks, minor flooding starts at 28 feet, moderate flooding at 40 feet and major flooding at 46 feet.
- Wahpeton: a 95% chance of reaching 10.2 feet, a 75% chance for 11.2 feet, 50% chance of 11.9 feet, a 10% chance for 14.8 feet and 5% chance for 15.6 feet. In Wahpeton, minor flooding begins at 11 feet, moderate flooding at 13 feet and major flooding at 15 feet.