Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
559 FGUS73 KBIS 222258 ESFBIS NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053- 055-057-059-061-065-083-085-087-089-093-103-105-230700- Probabilistic Hydrologic Outlook National Weather Service Bismarck ND 558 PM CDT Thu Aug 22 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 24 August through 22 November, 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... Flood risk across the Missouri and James River basins in North Dakota remains very low, which is normal for this time of year. Streamflow on some of the smaller tributaries west of the Missouri River have seen some ups and downs though as drought has steadily crept into western North Dakota. Out east, on the James River and Pipestem Creek watersheds, an unusually wet summer has kept water levels elevated at both Pipestem and Jamestown dams, which has in turn kept the James River below Jamestown elevated due to higher than normal releases from the dams. ...Missouri and Yellowstone Rivers... Above normal spring and early summer rains largely made up for deficits in winter snowpack early this spring, but water levels in both rivers have since fallen while remaining in the near-normal range for this time of year. Nonetheless, Missouri River mainstem reservoirs of Lake Sakakawea and Lake Oahe are higher than expected early on this spring. ...Snowpack Conditions... No snowpack exists within either the Missouri or James River basins of North Dakota. ...Current Drought Conditions... Timely and abundant rainfall east of the Missouri River corridor continues to keep drought at bay in central North Dakota and the James River Basin. However, west of the Missouri River and on up through Williams and Divide counties, drought designations have slowly expanded and gained in strength. Given the weather outlooks, this trend is likely to continue west and north of the Missouri River over the coming weeks and months. ...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, which were well above normal for most of late spring and early summer, are now a mixture of below normal south and west of the Missouri River, and above normal east and north of the Missouri River. This suggests areas east and north of the Missouri River will continue to see crops and native vegetation well supported by existing soil moisture, but crops and native vegetation south and west of the Missouri River are likely to start showing stress due to recent above normal temperatures and below normal precipitation. ...Weather Outlook... The near term 6-10 and 8-14 day outlooks generally favors below to near normal temperatures with below to near normal precipitation. Weeks 3-4 outlooks favor above normal temperatures with below normal precipitation. Overall, the month of September in in the equal chances designation for above normal, near normal or below normal temperatures and precipitation. Looking longer term, the 3-month outlooks for September, October and November favor above normal temperatures with the equal chances designation for precipitation. ...Ice Conditions... No ice exists 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. 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: 08/24/2024 - 11/22/2024 : 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 : 6 <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 : 6 <5 5 <5 <5 <5 :Missouri River Williston 22.0 24.0 26.0 : <5 8 <5 <5 <5 <5 :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 : 10 13 <5 <5 <5 <5 :Beaver Creek Linton 12.0 14.0 16.0 : <5 10 <5 7 <5 5 :Little Muddy River Williston 10.0 12.0 14.0 : <5 23 <5 8 <5 5 :Little Missouri River Marmarth 18.0 23.0 30.0 : <5 <5 <5 <5 <5 <5 Medora 15.0 18.0 20.0 : <5 <5 <5 <5 <5 <5 Watford City 20.0 24.0 30.0 : <5 <5 <5 <5 <5 <5 :Knife River Manning 15.0 17.0 20.0 : <5 7 <5 <5 <5 <5 :Spring Creek Zap 14.0 18.0 20.0 : <5 13 <5 6 <5 5 :Knife River Hazen 21.0 24.0 25.0 : <5 12 <5 10 <5 8 :Heart River Mandan 27.0 33.0 38.0 : <5 7 <5 <5 <5 <5 :Apple Creek Menoken 15.0 16.0 17.0 : 14 17 11 11 8 7 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: 08/24/2024 - 11/22/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Pipestem Pingree 5.4 5.4 5.4 5.4 6.9 8.6 11.5 :James River Grace City 5.1 5.1 5.1 5.1 6.0 7.2 13.2 LaMoure 9.3 9.3 9.3 9.3 9.6 12.8 15.6 :Missouri River Williston 15.3 15.3 15.4 15.4 15.6 15.7 17.4 :Cannonball River Regent 5.2 5.2 5.3 6.4 7.8 9.1 10.0 :Cedar Creek Raleigh 1.0 1.1 1.1 3.1 4.6 6.0 7.7 :Cannonball River Breien 2.1 2.2 2.5 5.1 7.4 9.8 13.3 :Beaver Creek Linton 4.5 4.6 4.6 5.2 6.6 8.9 11.2 :Little Muddy River Williston 4.6 4.6 4.6 4.6 4.7 5.8 7.8 :Little Missouri River Marmarth 1.2 1.2 1.2 1.2 2.0 5.3 6.9 Medora 1.8 1.8 1.8 1.8 3.7 6.1 7.6 Watford City 7.2 7.2 7.2 7.6 9.4 11.1 12.2 :Knife River Manning 6.3 6.3 6.3 6.4 7.3 9.9 12.9 :Spring Creek Zap 4.8 4.8 4.8 4.8 5.5 9.1 11.6 :Knife River Hazen 0.7 0.7 0.7 1.1 3.1 16.5 18.9 :Heart River Mandan 9.5 9.5 9.5 9.6 11.4 23.1 25.0 :Apple Creek Menoken 6.1 6.1 6.1 6.1 8.8 16.1 17.7 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: 08/24/2024 - 11/22/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Pipestem Pingree 5.1 4.9 4.7 4.7 4.7 4.7 4.7 :James River Grace City 4.8 4.6 4.4 4.4 4.4 4.4 4.4 LaMoure 8.1 6.9 6.8 6.8 6.8 6.8 6.8 :Missouri River :Cannonball River Regent 5.0 4.8 4.7 4.7 4.7 4.7 4.7 :Cedar Creek Raleigh 0.3 0.3 0.3 0.3 0.3 0.3 0.3 :Cannonball River Breien 2.0 2.0 2.0 2.0 1.9 1.9 1.9 :Beaver Creek Linton 4.4 4.4 4.4 4.4 4.4 4.4 4.4 :Little Muddy River Williston 4.5 4.5 4.5 4.5 4.5 4.5 4.5 :Little Missouri River Marmarth 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Medora 1.6 1.5 1.5 1.5 1.5 1.5 1.5 Watford City 7.1 7.1 7.1 7.1 7.1 7.1 7.1 :Knife River Manning 6.2 6.2 6.2 6.2 6.2 6.2 6.2 :Spring Creek Zap 4.8 4.8 4.8 4.8 4.8 4.8 4.8 :Knife River Hazen 0.6 0.6 0.6 0.6 0.6 0.6 0.6 :Heart River Mandan 9.3 9.2 8.7 8.6 8.5 8.4 8.4 :Apple Creek Menoken 5.2 4.9 4.5 4.4 4.3 4.3 4.3 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 September. $$ Schlag