####018009540#### FGUS73 KDLH 291700 ESFDLH MNC001-017-021-031-035-061-071-075-115-137-WIC003-007-013-031- 051-099-113-129-121200- PROBABILISTIC HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE Duluth MN 1100 AM CST Thu Feb 29 2024 ...Spring Flood and Water Resources Outlook... This Spring Flood Outlook covers NE Minnesota and NW Wisconsin for river forecast points on the headwaters of the Mississippi, Chippewa, St. Croix, and Rainy Rivers. The overall risk for spring flooding is below normal for these areas due to a near record low snowpack. ...Current Conditions... Precipitation since October has been near normal across the region however much of that has fallen as rain. Rainfall runoff was observed over the last week of December. No frost was present after the late December rains thus in addition to the rainfall runoff some rainfall percolated into the soil which soon re-froze. The lack of snowpack is the main driver of spring river forecasts. Near record or record low snowpack is occurring across NE Minnesota and NW Wisconsin. Without a insulating snowpack the soil frost is over 20 inches deep in Duluth and points north while Spooner, WI reported 11 inches of frost on February 29th. Frost depth is important because any heavy rainfall on frozen ground could generate efficient and rapid runoff. Rain on frozen ground is not well accounted for in the model solutions below. A widening area of abnormally dry to moderate drought conditions exists across the area and if trends continue a rapid intensification of drought impacts are expected. Rivers in the area responded to the late December rainfall with minor to moderate rises. Evidence of rivers freezing at higher stages is apparent across the Northland. River bank ice is much higher than current river heights. River ice has moved out of most reaches however recent cold temperatures may result in minor ice jamming which is not accounted for in the river model ensemble solutions below. ...Climate Outlook... Looking ahead at precipitation chances we see potential for a mixed precipitation event during the first weekend of March. Near 0.50 inches of precipitation is forecast with higher amounts possible as there is potential for thunderstorms. Above normal temperatures and a signal for above normal precipitation are forecast into the second week of March. The seasonal climate outlook for the three month period March through May shows a strong signal of above normal temperatures and an equal chance of above or below normal precipitation. 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: 03/04/2024 - 06/02/2024 : 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 -------- ----- ----- ----- : --- --- --- --- --- --- :Prairie River Taconite 10.0 12.0 13.0 : <5 <5 <5 <5 <5 <5 :Mississippi River Aitkin 13.0 15.0 18.0 : 16 53 <5 32 <5 7 Fort Ripley 10.5 12.5 26.0 : 12 41 <5 19 <5 <5 :St. Croix River Danbury 7.0 8.5 10.0 : <5 8 <5 <5 <5 <5 :Snake River Pine City 9.0 10.0 11.0 : <5 8 <5 5 <5 <5 :St. Louis River Scanlon 10.5 11.0 13.0 : <5 5 <5 <5 <5 <5 :Nemadji River Near South Superior 24.0 26.0 28.0 : <5 <5 <5 <5 <5 <5 :Tyler Forks Mellen 9.0 10.0 12.0 : 17 35 9 25 <5 5 :Bad River Near Odanah 16.0 18.0 20.0 : <5 <5 <5 <5 <5 <5 At Odanah 8.5 9.5 10.5 : <5 6 <5 <5 <5 <5 :South Kawishiwi River Ely 6.5 7.5 8.5 : <5 25 <5 12 <5 <5 :Little Fork River Little Fork 22.0 24.0 26.0 : <5 <5 <5 <5 <5 <5 :Vermilion River Crane Lake 14.0 16.0 18.0 : <5 14 <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: 03/04/2024 - 06/02/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Prairie River Taconite 3.9 4.2 4.8 5.5 6.6 7.7 8.1 :Mississippi River Aitkin 7.8 8.3 9.1 10.2 12.1 13.9 14.9 Fort Ripley 6.2 6.6 7.2 8.4 9.7 10.8 12.3 :St. Croix River Danbury 1.7 1.8 2.4 3.0 4.2 5.3 5.9 :Snake River Pine City 4.0 4.8 5.1 5.9 6.7 7.9 8.3 :St. Louis River Scanlon 4.9 5.2 5.8 6.4 7.4 8.1 9.2 :Nemadji River Near South Superior 10.1 10.7 11.9 14.6 18.7 22.2 22.8 :Tyler Forks Mellen 5.0 5.4 6.0 6.8 7.6 9.8 10.3 :Bad River Near Odanah 4.7 5.2 5.8 6.8 8.2 11.2 12.5 At Odanah 3.1 3.4 3.7 4.0 5.3 6.5 7.0 :South Kawishiwi River Ely 3.6 3.9 4.2 4.7 5.2 5.7 6.2 :Little Fork River Little Fork 4.5 4.8 5.8 6.6 7.6 9.6 12.1 :Vermilion River Crane Lake 7.6 7.9 9.2 10.1 10.9 12.2 12.5 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: 03/04/2024 - 06/02/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Prairie River Taconite 3.8 3.6 3.4 3.2 2.9 2.8 2.7 :Mississippi River Aitkin 6.6 6.1 5.3 4.2 3.4 2.5 2.2 Fort Ripley 5.5 5.2 5.0 4.7 4.2 3.9 3.7 :St. Croix River Danbury 1.2 1.1 1.0 0.9 0.9 0.8 0.8 :Snake River Pine City 3.2 3.2 3.1 3.0 3.0 2.8 2.8 :St. Louis River Scanlon 3.9 3.9 3.8 3.6 3.5 3.4 3.4 :Nemadji River Nemadji R nr Supe 4.7 4.4 4.3 4.1 3.9 3.8 3.7 :Tyler Forks Mellen 3.7 3.6 3.5 3.3 3.2 3.2 3.2 :Bad River Near Odanah 2.8 2.7 2.6 2.5 2.4 2.4 2.3 At Odanah 2.4 2.3 2.3 2.2 2.1 2.1 2.0 :South Kawishiwi River Ely 2.5 2.4 2.3 2.3 2.3 2.2 2.2 :Little Fork River Little Fork 3.8 3.8 3.6 3.5 3.3 3.0 2.8 :Vermilion River Crane Lake 7.2 6.8 6.7 6.5 6.2 5.9 5.7 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/dlh for more weather and water information. For additional information on stream flow conditions for USGS locations please reference https://dashboard.waterdata.usgs.gov For additional information on stream flow conditions at MNDNR sites www.dnr.state.mn.us/waters/csg/index.html or www.climate.umn.edu/dow/weekly_stream_flow/stream_flow_weekly.asp For more information on climate outlooks reference www.cpc.ncep.noaa.gov The next outlook will be issued March 14th. $$ ####018012054#### FGUS75 KCYS 291703 ESFCYS NEC007-013-033-045-105-123-157-165-WYC001-007-009-015-021-027-031- 141900- Probabilistic Hydrologic Outlook National Weather Service Cheyenne WY 1000AM MST Thu Feb 29 2024 ...Spring Flood and Water Resources Outlook Number 2... ...Below-Average Potential for Ice Jam Flooding This Spring... ...Below-Average Potential for Spring Snow melt Runoff Flooding... This Spring Flood and Water Resources Outlook is the second of three routine issuances for the Cheyenne Hydrologic Service Area which comprises seven counties in southeast Wyoming and eight counties in the Nebraska panhandle. This outlook includes the North Platte River main stem and its tributaries (the Laramie, Encampment, and Medicine Bow Rivers), the Niobrara, White and Little Snake Rivers. .Flood Outlook Summary... There is a below-average potential for flooding early this spring due to low-elevation snow melt, ice break up, and ice jams. These normally occur between February and April. The winter has brought extended periods of above-normal temperatures along with limited low-elevation snow pack. This limits the chances for flooding due to low-elevation snow melt or ice jams during periods of ice break-up on area lakes and rivers. The potential for flooding due to snow melt runoff in southeast Wyoming and the Nebraska Panhandle this spring is below-normal. At this time, the limited snowpack in the southern Laramie Range will limit the potential for snow melt flooding. In the Snowy and Sierra Madre ranges the snowpack has improved over the last two weeks and is approaching the long-term normal for this date. Near- normal snow packs in southeastern Wyoming generally translate into a low probability of flooding. However, a low probability of flooding is relatively normal for this region. There remains considerable opportunity for further accumulation of snowpack before the expected high-elevation snow melt in May and June. A normal or even low probability of flooding does not mean there is no chance of flooding. Even a lighter snowpack can generate flooding if there is a period of extremely warm temperatures and/or significant rainfall before the ground thaws. Once the ground has thawed, the flood potential for the rest of the spring and early summer will remain below normal. While the snow pack is currently near to below average. The potential for flooding, early or late in the season, will depend on future snowfall, temperature patterns, and spring rainfall. All of these factors affect the total amount of water stored in the snow pack and the speed with which it is released to the rivers. .Observed and Forecast Temperatures and Precipitation... Weather patterns since November have been warmer and dryer than average across the area. Outlooks by the Climate Prediction Center (CPC)for the period from 6 to 14 days indicate conditions that favor near-normal temperatures and above-normal precipitation. The latest one and 3-month outlooks for March, through May indicates no strong signal for above or below-normal temperatures or precipitation. .Snow Cover and Liquid Water Content... Mountain snow pack across southeast Wyoming is below normal to normal across most of southeast Wyoming. In southeastern Wyoming Basin snow water equivalents, measured at the Natural Resource Conservation Service (NRCS) SNOTEL stations, ranged from 42 percent of median in the South Platte River basin in southeast Wyoming to 107 percent of median in the Little Snake River basin. There remains almost 2 months until the median date of peak snow pack in most basins across the area. While the current outlooks are not overly optimistic for a robust runoff, March and April can have a disproportionate affect on the final snow pack accumulation for the season. Warm windy temperatures or late winter and early spring storms can cause dramatic, late-season, changes in total snow pack. Snow cover across the Nebraska Panhandle counties is extremely light and inconsistent. It is heavier in the southwestern Panhandle than in the north. Snow pack there contains relatively small amounts of water and should not be a major factor in Spring flooding. .Soil Conditions and Drought... Soil moisture in the area, as portrayed by the CPC, varies from near median to above median. Normal or above-normal conditions are prevalent across southeastern WY and the Nebraska Panhandle. Moderate to severe drought conditions continue to linger in the Carbon and Albany counties. Dry conditions have expanded northward from these areas but remain only abnormally dry and have not yet developed into drought. .Lake and River Conditions... It has been an exceptionally warm winter with only short periods of extremely cold weather. Despite this, most of the higher elevations lakes are iced over, although the ice thickness might be less than in most years. Lower elevations rivers and lakes have less ice than normal with large areas of open water. .Climate Outlooks... The latest outlooks issued by the Climate Prediction Center favor above-normal precipitation and near-normal temperatures for the next two weeks. The one and 3-month outlooks for the period from March through May shows no significant signal favoring above- normal or below-normal precipitation or temperatures. 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: 02/17/2024 - 09/30/2024 : 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 -------- ----- ----- ----- : --- --- --- --- --- --- :Encampment River Encampment 6.5 7.5 8.5 : <5 <5 <5 <5 <5 <5 :North Platte River Saratoga 8.5 9.5 10.5 : 32 40 12 17 <5 <5 Sinclair 9.0 10.0 11.0 : 28 31 12 17 5 6 :Medicine Box River Hanna 6.0 7.0 8.0 : <5 <5 <5 <5 <5 <5 :North Platte River Glenrock 7.0 8.0 9.0 : <5 <5 <5 <5 <5 <5 Orin 8.0 9.0 10.0 : <5 <5 <5 <5 <5 <5 :Laramie River Woods Landing 6.0 6.5 7.0 : <5 5 <5 <5 <5 <5 Laramie 9.0 10.0 11.0 : 10 22 <5 6 <5 <5 Bosler 7.5 8.5 9.5 : <5 8 <5 <5 <5 <5 Fort Laramie 7.0 8.0 9.0 : <5 7 <5 <5 <5 <5 :North Platte River Henry 5.5 6.5 7.5 : <5 <5 <5 <5 <5 <5 Mitchell 7.5 8.5 9.5 : 5 14 <5 8 <5 5 Minatare 7.5 8.5 9.5 : <5 6 <5 <5 <5 <5 Bridgeport 9.5 10.0 10.5 : <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: 02/17/2024 - 09/30/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Encampment River Encampment 4.1 4.3 4.6 4.9 5.3 5.5 6.1 :North Platte River Saratoga 6.2 6.6 7.4 8.1 8.9 9.6 10.0 Sinclair 5.4 5.9 6.9 7.9 9.1 10.2 10.8 :Medicine Box River Hanna 3.2 3.2 3.6 4.2 4.4 4.8 5.2 :North Platte River Glenrock 2.7 2.8 2.9 3.0 3.2 3.4 4.3 Orin 4.7 4.8 4.9 5.0 5.1 5.6 5.9 :Laramie River Woods Landing 2.0 2.0 2.3 2.8 3.4 4.0 4.5 Laramie 4.8 5.1 6.0 7.4 8.2 9.0 9.3 Bosler 1.3 1.3 1.7 3.0 5.4 6.2 6.6 Fort Laramie 3.0 3.2 3.4 3.5 4.2 5.6 6.1 :North Platte River Henry 3.5 3.6 3.7 3.8 3.9 4.1 4.4 Mitchell 3.0 3.1 3.4 3.8 4.6 6.5 7.4 Minatare 3.6 3.7 3.9 4.4 4.8 6.1 6.6 Bridgeport 5.0 5.0 5.2 5.6 6.0 6.8 7.2 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: 02/17/2024 - 09/30/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Encampment River Encampment 1.8 1.8 1.7 1.7 1.6 1.5 1.4 :North Platte River Saratoga 3.6 3.6 3.6 3.6 3.5 3.5 3.3 Sinclair 3.2 3.2 3.2 3.2 3.1 3.1 2.7 :Medicine Box River Hanna 2.1 2.1 2.1 2.0 2.0 2.0 1.9 :North Platte River Glenrock 0.9 0.9 0.9 0.9 0.8 0.8 0.8 Orin 3.5 3.5 3.5 3.5 3.5 3.5 3.5 :Laramie River Woods Landing 1.2 1.2 1.0 0.3 0.3 0.3 0.3 Laramie 3.8 3.7 3.7 3.6 3.6 3.5 3.5 Bosler 0.9 0.8 0.7 0.7 0.7 0.7 0.7 Fort Laramie 2.4 2.4 2.4 2.4 2.4 2.4 2.4 :North Platte River Henry 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Mitchell 0.8 0.6 0.3 0.1 0.1 0.1 0.1 Minatare 1.7 1.7 1.6 1.6 1.6 1.6 1.5 Bridgeport 3.9 3.9 3.8 3.8 3.8 3.8 3.8 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/cys for more weather and water information. The next outlook will be issued on or before March 15. $$ AJA