Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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847 FGUS73 KBIS 301828 ESFBIS NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053- 055-057-059-061-065-083-085-087-089-093-103-105-011830- Probabilistic Hydrologic Outlook National Weather Service Bismarck ND 128 PM CDT Thu May 30 2024 ...FLOOD AND WATER RESOURCES OUTLOOK... This Flood and Water Resources Outlook is for the James and Missouri basins of North Dakota, covering the period of 25 May through 23 August, 2024. This is a routine monthly issuance of flood probabilities for NWS forecast locations. These probabilities are issued 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... Coming into spring, the largest concern was generally the lack of snow and early spring rains. The month of May has been a welcome reprieve from the drought concerns, and all without any substantial flooding. These rains in May have alleviated soil moisture deficits and removed drought across all but the very southwestern corner of North Dakota. Despite the frequent rains, the prospects of widespread flooding remain below normal to near normal for this time of year. Nonetheless, as many long-term residents are keenly aware, this time of year...North Dakota always seems to be only a week or so away from either a drought or flood. This makes a continuation of the recent abundant moisture critical in determining how the summer goes. ...Missouri and Yellowstone Rivers... Recent moisture, both on the plains of eastern Montana and in the headwaters area have been above normal. This is welcome news given the near record low snowpack coming out of winter. Especially over the past few weeks, runoff and snowpack in the Rockies has helped both the Missouri and Yellowstone rivers from reaching the low water levels expected earlier on. Concerns still remain as overall runoff for the year is still expected to be below normal, but perhaps not as much below normal as expected just a couple months ago. ...Snowpack Conditions... No snowpack exists within either the Missouri or James River basins of North Dakota. ...Current Drought Conditions... Timely and abundant rainfall across North Dakota has removed drought designations from all but the very southwestern corner of the state. Nonetheless, with the region well into the growing season now, a continuation of the timely rains will be needed to keep drought concerns at bay going into what is the warmest time of the year. ...Reservoirs and Natural Wetlands... Streamflow, natural wetlands and small water features generally have normal to above normal water levels for this time of year. ...Soil Conditions... Soil moisture values have trended upwards over the past few weeks. SpoRT-LIS remote sensing of soil moisture now shows roughly three-fourths of the state with above normal soil moisture, with the remainder having near normal soil moisture values. This is a remarkable turnaround from having large areas with below normal soil moisture just last month. ...Weather Outlook... Near term, in the next few days, an above normal expectation for temperature along with below normal precipitation is favored to retain the above normal temperature and transition to an equal chances designation for above normal, near normal, or below normal precipitation. Looking longer term, the one and three-month outlooks place the entire state in the equal chances designation for above normal, near normal, or below normal temperature and precipitation. This pretty much depicts the Upper Great Plains as an island of uncertainty whereas the rest of the continental 48 states is generally favored for above normal temperatures. ...Ice Conditions... No ice is known to exist on any river or stream in North Dakota. 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: 05/25/2024 - 08/23/2024 : 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 <5 <5 <5 <5 <5 :James River Grace City 12.0 14.0 15.0 : 5 5 <5 <5 <5 <5 LaMoure 14.0 16.0 18.0 : 8 <5 5 <5 <5 <5 :Missouri River Williston 22.0 24.0 26.0 : 8 43 5 31 <5 14 :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 <5 <5 <5 <5 <5 :Cannonball River Breien 10.0 20.0 23.0 : 15 40 <5 <5 <5 <5 :Beaver Creek Linton 12.0 14.0 16.0 : 10 28 8 13 6 11 :Little Muddy River Williston 10.0 12.0 14.0 : 12 57 6 29 <5 5 :Little Missouri River Marmarth 18.0 23.0 30.0 : <5 6 <5 <5 <5 <5 Medora 15.0 18.0 20.0 : <5 13 <5 6 <5 5 Watford City 20.0 24.0 30.0 : <5 6 <5 5 <5 <5 :Knife River Manning 15.0 17.0 20.0 : <5 17 <5 <5 <5 <5 :Spring Creek Zap 14.0 18.0 20.0 : 6 15 5 12 <5 11 :Knife River Hazen 21.0 24.0 25.0 : 10 18 <5 16 <5 9 :Heart River Mandan 27.0 33.0 38.0 : 5 9 <5 <5 <5 <5 :Apple Creek Menoken 15.0 16.0 17.0 : 31 46 14 35 6 9 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: 05/25/2024 - 08/23/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Pipestem Pingree 5.4 5.4 5.4 5.5 7.9 10.0 10.8 :James River Grace City 4.8 4.8 4.8 5.0 6.8 9.0 11.8 LaMoure 8.1 8.1 8.1 8.1 9.0 12.4 16.4 :Missouri River Williston 19.4 19.6 20.0 20.4 21.0 21.8 23.7 :Cannonball River Regent 5.4 5.4 5.4 6.6 7.0 7.8 9.1 :Cedar Creek Raleigh 1.3 1.3 2.6 4.1 5.1 6.4 7.0 :Cannonball River Breien 2.5 3.0 4.6 7.0 8.4 10.4 11.4 :Beaver Creek Linton 5.0 5.0 5.2 6.7 9.8 12.1 16.6 :Little Muddy River Williston 4.7 4.7 4.9 5.9 7.2 11.1 12.1 :Little Missouri River Marmarth 1.1 1.1 1.1 1.2 2.6 6.0 6.8 Medora 1.7 1.7 1.7 1.8 3.3 6.1 7.1 Watford City 7.6 7.6 7.6 8.2 9.6 11.0 12.6 :Knife River Manning 6.3 6.3 6.4 7.1 9.3 11.4 13.1 :Spring Creek Zap 5.0 5.0 5.0 5.3 8.0 9.9 18.1 :Knife River Hazen 1.1 1.1 1.2 3.9 9.0 21.5 23.7 :Heart River Mandan 10.0 10.1 11.1 13.8 16.7 21.8 27.5 :Apple Creek Menoken 5.1 5.1 5.4 11.4 15.1 16.7 18.0 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: 05/25/2024 - 08/23/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Pipestem Pingree 5.1 5.0 5.0 4.9 4.8 4.8 4.8 :James River Grace City 4.6 4.6 4.6 4.5 4.5 4.5 4.5 LaMoure 7.9 7.8 7.6 7.5 7.4 7.4 7.4 :Missouri River :Cannonball River Regent 5.3 5.2 5.2 5.2 5.2 5.2 5.2 :Cedar Creek Raleigh 1.2 1.1 1.1 1.1 1.0 1.0 0.9 :Cannonball River Breien 2.4 2.3 2.2 2.2 2.1 2.1 2.1 :Beaver Creek Linton 4.6 4.5 4.5 4.4 4.3 4.3 4.3 :Little Muddy River Williston 4.7 4.7 4.7 4.7 4.7 4.7 4.7 :Little Missouri River Marmarth 1.1 1.1 1.0 1.0 0.9 0.9 0.9 Medora 1.4 1.4 1.3 1.3 1.2 1.2 1.2 Watford City 7.1 7.1 7.0 6.9 6.9 6.8 6.8 :Knife River Manning 6.2 6.2 6.2 6.0 6.0 6.0 6.0 :Spring Creek Zap 5.0 5.0 5.0 4.9 4.9 4.9 4.9 :Knife River Hazen 1.1 1.1 1.1 1.0 1.0 1.0 1.0 :Heart River Mandan 9.9 9.8 9.7 9.6 9.6 9.6 9.5 :Apple Creek Menoken 4.4 4.2 4.0 3.7 3.4 3.3 3.3 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 by the end of June. $$ Schlag