Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
899
FGUS73 KBIS 221820
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-241800-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
120 PM CDT Thu May 22 2025
...FLOOD AND WATER RESOURCES OUTLOOK...
This Flood and Water Resources Outlook is for the Missouri
and James River basins of North Dakota, covering the period of 24
May through 22 August, 2025.
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...
In general, the majority of forecast locations in the Missouri and
James River basins across North Dakota are near to somewhat below
normal for this time of year.
...Snowpack Conditions...
No snow exists in the Missouri and James River basins of North
Dakota.
...The Missouri and Yellowstone rivers west of Williston...
The headwaters areas for both the Yellowstone and Missouri rivers
continue to melt off a near-normal snowpack, but the overall runoff
remains somewhat lower than normal this year.
...Current Drought Conditions...
Recent rainfall has been very impactful on the conditions that
influence drought designations. The recent, and very lengthy, spring
wildfire season appears to be in the rear-view mirror at this point.
Similarly, dismal moisture totals over the past several months have
now given way to a very wet pattern over the past couple of weeks.
Lastly, very low soil moisture values have recently been replenished
and are on the other end of the statistical spectrum. Accordingly,
widespread improvements have been made to the USDM depictions of
drought across North Dakota. D0 through D3 conditions (Abnormally
Dry to Extreme drought) remain in western North Dakota, while D0 to
D1 (Moderate Drought) conditions impact the northeastern and
southeastern counties, respectively. Nonetheless, the near-term
trend should be of continued improvement over the next few weeks
before a return to warmer and drier than normal conditions can
reasonably reverse the current trend of improved designations.
...Reservoirs and Natural Wetlands...
In general, the Missouri River reservoirs of Lake Oahe and Lake
Sakakawea are at the lower end of normal for expectations this
year. Smaller man-made features and natural wetlands stockdams and
have the the larger reservoirs have faired reasonably wellDue to the
early melt of a very uneven, but generally below normal
snowpack this year, the net results vary wildly. Some areas have
seen enough runoff to fill the smaller natural and man-made water
features, but overall runoff has been lacking. This is a cause for
concern on smaller water supply features.
...Soil Conditions...
Recent rainfall amounts between four and six inches over the past 10
days have significantly improved soil moisture across western and
central North Dakota. Locations west of the Missouri River had
single digit percentiles for soil moisture just one week ago, are
now widely in the 80th to 90th percentile.
...Weather Outlook...
The near term 6-10 and 8-14 day weather outlooks favor above normal
temperatures with below normal precipitation across North Dakota.
Looking out even longer, the weeks 3-4 outlooks favor above normal
temperatures and above normal precipitation for all of North Dakota.
And finally, in the 3-month outlooks covering June, July, and
August...the region is again favored for above normal temperatures
with a favoring for below normal precipitation. This would suggest
summer will bring hot and dry weather into the area by the beginning
of July.
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: 05/24/2025 - 08/22/2025
: 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 : 6 5 5 <5 <5 <5
LaMoure 14.0 16.0 18.0 : 9 <5 6 <5 <5 <5
:Missouri River
Williston 22.0 24.0 26.0 : 6 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 : 18 41 <5 <5 <5 <5
:Beaver Creek
Linton 12.0 14.0 16.0 : 28 28 9 13 7 11
:Little Muddy River
Williston 10.0 12.0 14.0 : 24 56 12 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 : 19 17 <5 <5 <5 <5
:Spring Creek
Zap 14.0 18.0 20.0 : 12 15 9 12 6 11
:Knife River
Hazen 21.0 24.0 25.0 : 19 18 15 16 9 9
:Heart River
Mandan 27.0 33.0 38.0 : 6 9 <5 <5 <5 <5
:Apple Creek
Menoken 15.0 16.0 17.0 : 42 46 15 35 6 11
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: 05/24/2025 - 08/22/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 7.3 7.3 7.3 7.3 8.7 10.6 11.2
:James River
Grace City 6.6 6.6 6.6 6.6 8.4 11.2 13.9
LaMoure 8.3 8.3 8.3 8.3 9.1 13.3 16.5
:Missouri River
Williston 19.1 19.1 19.2 19.6 20.1 21.1 23.0
:Cannonball River
Regent 6.1 6.1 6.2 7.1 7.6 9.3 10.6
:Cedar Creek
Raleigh 2.9 2.9 3.1 4.3 5.3 6.6 8.1
:Cannonball River
Breien 6.3 6.3 6.4 7.3 9.5 10.9 12.0
:Beaver Creek
Linton 6.0 6.0 6.9 9.8 12.0 13.7 17.4
:Little Muddy River
Williston 5.1 5.1 6.9 8.6 9.9 12.5 13.3
:Little Missouri River
Marmarth 1.4 1.4 1.4 2.7 4.8 9.2 11.4
Medora 2.7 2.7 3.2 4.5 6.3 10.0 12.0
Watford City 10.7 10.7 10.7 11.0 13.4 14.8 16.6
:Knife River
Manning 7.1 7.1 7.7 9.3 12.9 16.0 16.1
:Spring Creek
Zap 5.2 5.2 6.3 8.6 11.5 17.3 23.0
:Knife River
Hazen 6.1 6.1 6.1 11.8 19.8 24.6 26.1
:Heart River
Mandan 16.4 16.4 16.4 16.8 22.0 24.0 29.2
:Apple Creek
Menoken 14.4 14.4 14.4 14.7 15.4 16.6 17.9
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: 05/24/2025 - 08/22/2025
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.5 5.5 5.4 5.4 5.4 5.4 5.4
:James River
Grace City 4.7 4.6 4.5 4.3 4.3 4.3 4.3
LaMoure 8.1 8.0 7.7 7.3 7.1 7.0 7.0
:Missouri River
:Cannonball River
Regent 5.1 5.0 5.0 5.0 4.9 4.9 4.9
:Cedar Creek
Raleigh 0.8 0.7 0.6 0.5 0.4 0.4 0.3
:Cannonball River
Breien 2.5 2.4 2.3 2.2 2.2 2.1 2.1
:Beaver Creek
Linton 4.6 4.6 4.5 4.4 4.4 4.3 4.3
:Little Muddy River
Williston 4.7 4.4 4.4 4.3 4.3 4.3 4.3
:Little Missouri River
Marmarth 1.2 1.1 1.0 1.0 0.9 0.9 0.8
Medora 2.0 2.0 2.0 2.0 2.0 2.0 2.0
Watford City 7.6 7.2 7.1 7.0 6.9 6.7 6.7
:Knife River
Manning 6.5 6.4 6.3 6.2 6.2 6.1 6.1
:Spring Creek
Zap 4.8 4.8 4.7 4.7 4.7 4.7 4.7
:Knife River
Hazen 1.3 1.2 1.1 1.0 1.0 0.9 0.9
:Heart River
Mandan 9.5 9.4 9.3 9.2 9.1 9.1 9.1
:Apple Creek
Menoken 5.9 5.8 5.8 5.7 5.7 5.7 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/bis for more weather and water
information.
The next outlook will be issued by the end of June.
$$
Schlag