####018009454#### FGUS73 KABR 151926 ESFABR MNC011-155-SDC013-017-021-025-029-031-037-039-041-045-049-051-057- 059-065-069-075-085-089-091-107-109-115-117-119-129-231930- Probabilistic Hydrologic Outlook National Weather Service Aberdeen SD 126 PM CST Thu Feb 15 2024 ...Spring Flood Outlook... This spring flood outlook is for the rivers and streams in northeast South Dakota, portions of central South Dakota, and portions of west central Minnesota. A current lack of widespread snow cover, areas of thawed ground, and decreasing river ice currently points toward a below normal flood risk over the area over the next 90 days. With this said, additional heavy precipitation events or cold outbreak could change the flood risk going forward. Changes to the flood risk factors will continue to be monitored and updates provided in future outlooks. The outlook for the next two weeks is for increased chances for above normal temperatures and near normal chances for precipitation. The 90 day outlook for February through April shows equal chances for below, near or above normal precipitation and temperatures. ...Current snow conditions... Current snow depth ranges from little to no snow pack across the northern part of South Dakota and west central Minnesota, to areas of 2 to 7 inches along a line from Pierre to Redfield to Watertown. The liquid water equivalent with the snow pack is generally a track to less then one inch. ...Current soil conditions... Soil moisture is above normal across the entire area. Frost depths are below 1 foot across much of the area, with the exception of north central South Dakota, where they range from 1 to 2 feet. The only areas remaining in drought at this time area Deuel and Hamlin counties, and portions of Grant, Codington and Clark counties. ...Current river conditions... Most of the rivers are iced over, but reports indicate that there are open, or very thinly covered, spots. River levels and flows are generally running near to below normal across the region. The threat for break-up ice jams appears low at this time. Any potential ice jam flooding will be determined by how fast the remaining ice melts and how much additional flow can get into the rivers to raise and break up the existing ice cover before it melts. ...Probabilistic Outlooks... In Table 1 below, the current (CS) and historical (HS) or normal probabilities of exceeding minor...moderate...and major flood stage are listed for the valid time period. CS values indicate the probability of reaching a flood category based on current conditions. HS values indicate the probability of reaching a flood category based on historical or normal conditions. When the value of CS is greater than HS...the probability of exceeding that level is higher than normal. When the value of CS is less than HS...the probability of exceeding that level is lower than normal. ...Table 1--Probabilities for minor...moderate and major flooding... Valid Period: Valid Period: 02/19/2024 - 05/19/2024 : Current and Historical : Chances of Exceeding : Flood Categories : as a Percentage (%) Categorical : Flood Stages (FT) : Minor Moderate Major Location Minor Mod Major : CS HS CS HS CS HS -------- ----- ----- ----- : --- --- --- --- --- --- :Elm River Westport 14.0 16.0 19.0 : 11 28 9 22 5 9 :James River Columbia 13.0 16.0 18.0 : 38 54 28 43 20 29 Stratford 14.0 17.0 18.5 : 35 54 24 42 11 29 Ashton 13.0 14.0 16.0 : 30 52 29 45 20 43 Redfield 20.0 22.0 25.0 : 20 42 19 41 16 39 :Snake Creek Ashton 11.5 13.0 16.0 : 18 45 17 40 8 34 :Turtle Creek Redfield 7.0 10.0 15.0 : 48 47 24 44 14 30 :Big Sioux River Watertown 10NW 10.0 11.0 12.0 : <5 19 <5 <5 <5 <5 Watertown Conifer 9.0 10.0 12.0 : 7 35 <5 29 <5 <5 Watertown Broadwy 10.5 11.0 13.5 : 8 35 7 33 <5 <5 Castlewood 9.0 11.0 16.0 : 14 40 7 28 <5 <5 :Grand River Little Eagle 15.0 17.0 21.0 : <5 27 <5 17 <5 6 :Moreau River White Horse 21.0 23.0 25.0 : <5 22 <5 17 <5 11 :Bad River Fort Pierre 21.0 25.0 27.0 : 6 9 5 5 <5 <5 :Little Minnesota Peever 17.0 22.0 24.0 : 16 24 <5 <5 <5 <5 :Minnesota River Big Stone Lake 971.5 973.0 975.0 : <5 6 <5 <5 <5 <5 Legend CS = Conditional Simulation (Current Outlook) HS = Historical Simulation FT = Feet In Table 2 below...the 95 through 5 percent columns indicate the probability of exceeding the listed stage levels (FT) for the valid time period. ...Table 2--Exceedance Probabilities... Chance of Exceeding Stages at Specific Locations Valid Period: Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Elm River Westport 5.1 5.1 5.1 7.2 10.0 15.5 19.3 :James River Columbia 7.4 7.4 8.0 10.6 17.6 18.6 19.9 Stratford 9.7 9.7 9.7 10.6 16.9 18.8 20.1 Ashton 6.0 6.0 6.0 6.6 14.2 19.9 26.9 Redfield 6.8 6.8 6.8 8.9 15.6 30.5 32.7 :Snake Creek Ashton 3.0 3.2 4.0 5.5 7.5 15.1 20.6 :Turtle Creek Redfield 4.5 4.5 5.0 6.6 9.1 17.2 18.3 :Big Sioux River Watertown 10NW 4.2 4.3 4.7 5.2 7.5 8.8 9.8 Watertown Conifer 3.8 3.8 4.0 4.4 6.0 7.7 9.4 Watertown Broadwy 5.2 5.2 5.6 5.8 7.6 9.4 11.3 Castlewood 5.3 5.3 5.5 5.8 7.4 9.3 11.1 :Grand River Little Eagle 3.0 3.0 4.4 5.6 7.7 9.6 10.5 :Moreau River White Horse 3.2 4.7 5.8 7.2 9.9 12.7 15.5 :Bad River Fort Pierre 4.2 5.2 6.5 8.4 12.4 16.8 24.1 :Little Minnesota Peever 12.3 12.5 13.3 14.9 16.4 18.1 20.5 :Minnesota River Big Stone Lake 968.0 968.0 968.0 968.0 968.2 969.8 970.5 In Table 3 below...the 95 through 5 percent columns indicate the probability of falling below the listed stage levels (FT) for the valid time period. ...Table 3--Nonexceedance Probabilities... Chance of Falling Below Stages at Specific Locations Valid Period: LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Elm River Westport 4.7 4.7 4.4 4.0 3.9 3.9 3.9 :James River Columbia 6.4 6.1 5.9 5.7 5.7 5.7 5.7 Stratford 8.0 7.8 6.9 6.5 6.4 6.4 6.4 Ashton 5.3 5.0 4.5 4.1 3.9 3.9 3.8 Redfield 6.2 6.1 5.5 5.1 4.8 4.8 4.8 :Snake Creek Ashton 2.9 2.9 2.9 2.8 2.8 2.5 2.5 :Turtle Creek Redfield 3.8 3.7 3.6 3.3 3.2 3.1 3.1 :Big Sioux River Watertown 10NW 4.0 4.0 3.9 3.8 3.8 3.8 3.8 Watertown Conifer 3.7 3.7 3.7 3.7 3.6 3.6 3.6 Watertown Broadwy 5.1 5.1 5.1 5.0 5.0 4.9 4.9 Castlewood 5.0 4.9 4.9 4.7 4.6 4.6 4.6 :Grand River Little Eagle 2.6 2.6 2.6 2.6 2.5 2.4 2.4 :Moreau River White Horse 2.3 2.3 2.3 2.3 2.3 2.2 2.2 :Bad River Fort Pierre 0.8 0.5 0.5 0.5 0.5 0.5 0.5 :Little Minnesota Peever 10.5 10.5 10.4 10.0 9.7 9.7 9.7 :Minnesota River Big Stone Lake 967.4 967.4 967.4 967.4 967.4 967.4 967.4 These long-range probabilistic outlooks contain forecast values that are calculated using multiple season scenarios from 30 or more years of climatological data...including current conditions of the river...soil moisture...snow cover and 30 to 90 day long-range outlooks of temperature and precipitation. By providing a range of probabilities...the level of risk associated with long-range planning decisions can be determined. These probabilistic forecasts are part of the National Weather Service's Advanced Hydrologic Prediction Service. Visit our web site weather.gov/abr for more weather and water information. The next outlook will be issued on February 29th, 2024. $$ Parkin