Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
950 FGUS73 KBIS 141511 ESFBIS NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053- 055-057-059-061-065-083-085-087-089-093-103-105-161400- Probabilistic Hydrologic Outlook National Weather Service Bismarck ND 1011 AM CDT Thu Mar 14 2024 ...SPRING FLOOD AND WATER RESOURCES OUTLOOK... This Spring Flood and Water Resources Outlook is for the James and Missouri basins of North Dakota, covering the period of 16 March through 14 June, 2024. This is the third and final edition of the Spring Flood and Water Resources Outlook. On 28 March, the NWS will revert back to routinely issuing of flood probabilities on, or around, the fourth Thursday of every month. The following message has four sections. The first provides some text on the highlights of this outlook and conditions affecting the local hydrology. The second section gives the current and historical risks of flooding as determined by the Ensemble Streamflow Forecast model of the National Weather Service. The third section gives the current probabilities for reaching flood stage at the listed forecast locations. And finally, the fourth section covers the risk of the river sites falling below the listed stages. ...Flood Outlook Highlights... Given the unseasonably warm weather over the past week, the Missouri and James river basins of North Dakota are in an active melt pattern that is currently removing what little snow remains on the countryside. No damaging high water is expected and the below probabilities are largely in effect for once the current melt pattern is complete. As such, the probabilities below largely represent the risk posed by spring rains. Accordingly, as the wet ground surface continues to thaw, these probabilities reflect below normal to well below normal risks of widespread flooding. However, if history is any lesson, a few examples of minor flooding due to heavy rains cannot be ruled out as they commonly occur in late spring. Perhaps the greater risk going into spring continues to be the existing long-term trend of below normal precipitation. If this trend continues, increased and expanded drought designations are a real concern going forward as temperatures increase and soils dry out. ...Missouri and Yellowstone Rivers... In western North Dakota the Missouri and Yellowstone rivers above Lake Sakakawea are back down to normal water levels for this time of year despite having recently experienced modest runoff. The overall snowpack on the plains and headwaters area of Montana continues to trend well below normal for this time of year, and remains in contention for the lowest observed Snow-Water Equivalent (SWE) going into spring for the Missouri and Yellowstone rivers in the past 30 years. The ice on the Missouri River below Garrison Dam has now eroded to well south of the Bismarck and Mandan area. Given the short-term and mid-term temperature forecasts and outlooks, this signals the end of ice jam related high water along the Missouri River below Garrison Dam even though there will be at least some ice yet to hit the Missouri River from upstream tributaries. ...Snowpack Conditions... Snowpack across the Missouri and James River basins of North Dakota is largely melted and making its way to local streams. While areas protected from lengthy direct sunlight during the day still have minor amounts of snow, there is not enough volume in that hidden snow to pose a threat of flooding by itself. ...Current Drought Conditions... A steady, but slow expansion of D0 (Unusually Dry) continues to plague much of North Dakota and the Northern Great Plains. A continuation of the dry pattern in place will increase wildfire and drought concerns going into spring as the ground thaws and the region enters its growing season. ...Reservoirs and Natural Wetlands... Despite an overall snow deficity across most of the state, runoff due to a wet and frozen ground surface has been remarkable at times. Most small livestock dams and natural wetlands are near normal for early spring water levels. Larger water impoundments though are at greater risk of below normal water levels going into spring and summer. ...Soil Conditions... Soil moisture values across the Missouri and James basins are generally near normal going down to near 40 inches (100 cm), but the ground surface is much wetter than normal due to early winter rain and melting snow. This wet and frozen ground surface will increasingly thaw and allow future precipitation to more readily infiltrate into the ground. ...Weather Outlook... The Climate Prediction Center 6-10 and 8-14 day outlooks favor below normal temperatures and above normal chances for precipitation. That generally carries the state through the remainder of March, however the weeks 3-4 outlooks bring back a fairly strong favoring of above normal temperatures with a slight to strong favoring of below normal precipitation. Looking longer term at the three-month outlook for March, April, and May...a favoring for above normal temperatures with precipitation placed in the equal chances category for above normal, near normal, or below normal precipitation. ...Ice Conditions... Ice is quickly waning across most of North Dakota, although the northernmost areas are somewhat slower to see degradation of its ice. Many, but not all, small streams in the southern half of North Dakota area already nearly free of ice. Ice on the small lakes and natural wetlands continues to soften and degrade as runoff arrives. 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: 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 -------- ----- ----- ----- : --- --- --- --- --- --- :Pipestem Pingree 11.0 13.0 15.0 : <5 12 <5 <5 <5 <5 :James River Grace City 12.0 14.0 15.0 : <5 15 <5 9 <5 8 LaMoure 14.0 16.0 18.0 : <5 17 <5 8 <5 <5 :Missouri River Williston 22.0 24.0 26.0 : 7 42 <5 27 <5 8 :Cannonball River Regent 22.0 24.0 26.0 : <5 <5 <5 <5 <5 <5 :Cedar Creek Raleigh 12.0 14.0 16.0 : <5 9 <5 5 <5 <5 :Cannonball River Breien 10.0 20.0 23.0 : 12 58 <5 <5 <5 <5 :Beaver Creek Linton 12.0 14.0 16.0 : <5 45 <5 31 <5 13 :Little Muddy River Williston 10.0 12.0 14.0 : 8 70 <5 42 <5 10 :Little Missouri River Marmarth 18.0 23.0 30.0 : <5 6 <5 <5 <5 <5 Medora 15.0 18.0 20.0 : <5 24 <5 8 <5 6 Watford City 20.0 24.0 30.0 : <5 14 <5 5 <5 <5 :Knife River Manning 15.0 17.0 20.0 : <5 26 <5 <5 <5 <5 :Spring Creek Zap 14.0 18.0 20.0 : 9 31 6 15 <5 8 :Knife River Hazen 21.0 24.0 25.0 : 14 43 8 31 5 26 :Heart River Mandan 27.0 33.0 38.0 : <5 19 <5 <5 <5 <5 :Apple Creek Menoken 15.0 16.0 17.0 : 26 58 16 55 <5 34 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% -------- ------ ------ ------ ------ ------ ------ ------ :Pipestem Pingree 5.2 5.2 5.2 5.2 5.6 7.1 8.4 :James River Grace City 4.3 4.3 4.3 4.4 5.5 6.3 6.7 LaMoure 7.6 7.6 7.6 7.6 8.1 9.1 10.6 :Missouri River Williston 17.6 18.1 18.9 19.4 20.3 21.8 22.8 :Cannonball River Regent 5.2 5.2 5.3 6.5 7.9 8.7 8.9 :Cedar Creek Raleigh 0.9 1.0 2.0 2.9 4.5 5.4 5.7 :Cannonball River Breien 2.3 2.5 3.5 5.6 8.1 10.2 10.6 :Beaver Creek Linton 4.3 4.4 4.6 5.5 6.6 9.8 11.4 :Little Muddy River Williston 4.3 4.3 5.3 7.1 8.4 9.6 11.5 :Little Missouri River Marmarth 1.1 1.1 1.1 1.4 5.1 8.2 11.2 Medora 1.5 1.5 1.5 2.4 5.5 8.6 11.8 Watford City 7.1 7.1 7.1 8.0 10.0 13.0 15.1 :Knife River Manning 6.4 6.4 6.4 8.3 9.5 12.6 13.6 :Spring Creek Zap 4.9 5.0 5.8 7.2 8.7 12.0 19.0 :Knife River Hazen 2.9 2.9 4.9 8.9 14.6 23.7 25.2 :Heart River Mandan 12.6 12.6 13.5 15.5 21.3 23.5 25.7 :Apple Creek Menoken 6.4 6.4 7.0 8.9 15.1 16.7 16.9 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% -------- ------ ------ ------ ------ ------ ------ ------ :Pipestem Pingree 5.1 5.1 5.1 5.1 5.1 5.1 5.1 :James River Grace City 4.2 4.2 4.2 4.1 4.1 4.1 4.1 LaMoure 7.4 7.3 7.0 6.9 6.9 6.8 6.8 :Missouri River :Cannonball River Regent 5.0 5.0 5.0 5.0 5.0 4.9 4.9 :Cedar Creek Raleigh 0.3 0.3 0.3 0.3 0.3 0.3 0.3 :Cannonball River Breien 2.1 2.1 2.1 2.1 2.1 2.0 2.0 :Beaver Creek Linton 4.2 4.2 4.2 4.2 4.2 4.2 4.2 :Little Muddy River Williston 4.3 4.3 4.3 4.3 4.3 4.3 4.2 :Little Missouri River Marmarth 1.1 1.1 1.1 1.0 0.9 0.9 0.9 Medora 1.4 1.4 1.4 1.3 1.3 1.2 1.2 Watford City 7.0 7.0 7.0 7.0 6.8 6.8 6.8 :Knife River Manning 6.3 6.3 6.3 6.3 6.2 6.0 6.0 :Spring Creek Zap 4.9 4.9 4.8 4.8 4.8 4.8 4.8 :Knife River Hazen 0.8 0.7 0.6 0.5 0.3 0.3 0.2 :Heart River Mandan 11.0 11.0 10.9 10.8 10.8 10.7 10.7 :Apple Creek Menoken 4.8 4.6 4.5 4.0 3.5 3.3 3.2 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/bis for more weather and water information. The next outlook will be issued on, or around the fourth Thursday of March. $$ Schlag