FGUS73 KLBF 141301 ESFLBF NEC005-009-015-017-029-031-041-049-063-069-071-075-085-089-091-101- 103-111-113-115-117-135-149-161-171-183-270000- Probabilistic Hydrologic Outlook National Weather Service North Platte NE 800 AM CST Thu March 14 2024 ...Spring Flood and Water Resource Outlook Number 3... ...A Below Average Flood Potential from Spring Snowmelt... This Spring Flood and Water Resource Outlook is for the North Platte Hydrologic Service Area, which covers western and north central Nebraska. The river basins include: the North Platte and South Platte Rivers and the Platte River in western Nebraska, Frenchman Creek and Stinking Water Creek in southwest Nebraska, the Loup and Dismal Rivers in the Sandhills of Nebraska, and portions of the Elkhorn and Niobrara Rivers in north central Nebraska. .Flood Outlook Summary... A below average flood potential is expected from spring snowmelt. No snow cover currently exists across western and north central Nebraska. Rivers are currently ice free. Temperatures have remained above normal the first two weeks of March. The potential for rainfall induced flash flooding is not quantifiable. This type of flooding is most likely to occur during the late spring and summer months. .Snow Cover and Mountain Snowpack... As of March 14th, no snow cover existed across western and north central Nebraska. March and April are typically snowy months, so additional snowfall is possible. Snowpack conditions in the North Platte and South Platte River Basins in Colorado and Wyoming are above average. Snow water equivalents ranged from near 105 percent of average for the North Platte Basin and 110 percent of average for the South Platte Basin. A below average flood potential is expected from mountain snowmelt runoff. .Reservoir Conditions... Normal operations are ongoing at reservoirs along the North Platte River for this time of year. Releases from these dams have been limited through the winter months, with inflows generally coming from melting snow. Because of these operations, reservoir levels have risen though the winter months. The current reservoir storage across Wyoming, as well as Lake McConaughy, are below average for this time of year. .Soil Conditions and Frost Depths... Soil moisture was near normal to below normal across the southeast panhandle and southwest Nebraska to above to much above normal across north central Nebraska. According to the U.S. Drought Monitor, abnormally dry conditions remained across far southwest Nebraska, which includes the Frenchman Creek Basin. Otherwise, no drought conditions currently exist. As of March 14th, soil temperature sensors indicate 4 inch soil temperatures range from 42 to 52 degrees. .River and Lake Ice Conditions... Monthly average streamflow was average to above average across the central and northern Sandhills, including the Niobrara, Elkhorn and Loup River Basins. Average to much below average streamflow was indicated across the southeast panhandle and southwest Nebraska, including the Platte River Basin, and Frenchman Creek Basin. Lakes and rivers were currently ice free. .Seasonal Precipitation... Precipitation so far this water year, since October 1, 2023, has ranged from near normal to below normal across the southeast panhandle into west central and southwest Nebraska to much above normal across Custer County northward across the eastern half of north central Nebraska. These areas which received from 5 to 11 inches, were from 130 to over 200 percent of normal. .Weather Outlooks... Water temperatures in the tropical Pacific Ocean remain above average, with El Nino conditions. The outlook indicates weak El Nino conditions will persist into March and April. For the late winter and spring months, this weather pattern will typically favor near normal temperatures with above normal precipitation across the Central Plains. According to the Climate Prediction Center, as of March 14th, the latest 8 to 14 day outlook calls for below average temperatures with above average precipitation. The latest 30 day outlook for March calls for equal chances for above, below or average temperatures and above average precipitation. The latest 90 day outlook for March, April and May indicates near average temperatures with near average precipitation going into this spring. .Numerical Weather Outlooks... For the Frenchman Creek, North Platte, South Platte, Platte, Elkhorn, and Niobrara Rivers...long range probabilistic outlooks are issued for the water year from December through May. All other months and locations are 90 day probabilistic outlooks. In Table 1 below...the current (CS) and historical (HS) or normal probabilities of exceeding minor...moderate...and major flood stages 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 more 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: 03/16/2024 - 06/14/2024 : 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 -------- ----- ----- ----- : --- --- --- --- --- --- :North Platte River Lisco 4.0 5.0 6.0 : 7 13 <5 6 <5 <5 Lewellen 8.0 9.0 10.0 : 11 18 <5 6 <5 <5 North Platte 6.0 6.5 7.0 : 21 24 12 19 11 14 :South Platte River Roscoe 9.0 11.0 13.0 : 29 14 12 9 9 7 North Platte 13.0 14.0 15.0 : 11 9 9 8 7 <5 :Elkhorn River Ewing 1N 9.0 10.0 12.0 : <5 5 <5 <5 <5 <5 :Platte River Brady North Chann 7.5 9.0 11.0 : 36 33 23 18 11 11 :Frenchman Creek Palisade 7.0 8.0 9.0 : 18 13 5 <5 <5 <5 :Stinking Water Creek Palisade 2NW 10.0 11.0 12.0 : <5 <5 <5 <5 <5 <5 :Niobrara River Sparks 6.0 12.0 16.0 : <5 <5 <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: 03/16/2024 - 06/14/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :North Platte River Lisco 1.3 1.3 1.4 1.8 2.3 3.0 4.2 Lewellen 5.9 5.9 5.9 6.5 7.2 8.1 8.6 North Platte 4.8 4.8 4.8 4.9 5.5 7.2 8.6 :South Platte River Roscoe 5.4 5.4 6.3 7.9 9.3 11.9 15.4 North Platte 7.6 7.7 8.6 9.9 11.3 13.6 16.1 :Elkhorn River Ewing 1N 2.5 2.5 3.3 5.0 6.7 8.3 8.7 :Platte River Brady North Chann 2.2 3.2 4.6 6.5 8.6 11.6 12.3 :Frenchman Creek Palisade 3.8 3.8 4.0 4.9 5.8 7.8 8.0 :Stinking Water Creek Palisade 2NW 3.2 3.2 3.2 3.6 4.5 6.0 6.6 :Niobrara River Sparks 3.0 3.1 3.2 3.4 3.6 4.0 4.1 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: 03/16/2024 - 06/14/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :North Platte River Lisco 1.1 1.0 1.0 1.0 0.9 0.9 0.9 Lewellen 5.5 5.4 5.3 5.2 5.2 5.2 5.1 North Platte 4.7 4.7 4.6 4.5 4.5 4.5 4.5 :South Platte River Roscoe 3.3 3.3 3.3 2.3 2.1 2.0 2.0 North Platte 6.9 6.9 6.9 6.8 6.7 6.7 6.7 :Elkhorn River Ewing 1N 2.3 2.3 2.2 2.1 1.9 1.7 1.6 :Platte River Brady North Chann 2.1 2.1 2.0 0.0 0.0 0.0 0.0 :Frenchman Creek Palisade 3.6 3.6 3.5 3.4 3.4 3.3 3.3 :Stinking Water Creek Palisade 2NW 2.8 2.7 2.5 2.2 1.6 0.0 0.0 :Niobrara River Sparks 3.0 3.0 2.9 2.9 2.9 2.9 2.8 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/lbf for more weather and water information. This is the third spring flood and water resource outlook for 2024. Long-range probabilistic outlooks are issued near the end of the month throughout the year. $$ Roberg