Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
339
FGUS73 KBIS 291840
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-311800-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
140 PM CDT Fri Aug 29 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 31 August, 2025
through 29 November, 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...
All 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
are now well on the backside of the snowmelt runoff and are at
normal late summer flows.
...Current Drought Conditions...
Rainfall over the past month has effectively removed all drought
designations within the Souris River Basin of North Dakota.
...Reservoirs and Natural Wetlands...
While the dry spring runoff season was very detrimental to filling
reservoirs and natural wetlands, they have since fared reasonably
well given the abundant June and July rains.
...Soil Conditions...
Soil moisture values have started to decrease and there is now very
little in the way of areas with above normal soil moisture for this
time of year. Rather, it is a near even mix of below normal and
near normal soil moisture readings across the Missouri and James
River basins of North Dakota.
...Weather Outlook...
The near term 6-10 and 8-14 day weather outlooks reflect a bit of a
transition from cooler than normal to slightly above normal
temperatures with below normal precipitation in the near term, which
transitions towards more near normal in the later period. Looking a
little longer term at the one-month outlooks for September, there is
a slight favoring for above normal temperatures with below normal
precipitation in the western half of the basin.
Looking even longer into the future, the three-month outlooks
covering September, October and November have the region in the
equal chances category for above normal, near normal, or below
normal temperatures and precipitation. This longer term uncertainty
is likely associated with the slight favoring for a transition to a
La Nina weather pattern sometime in the late fall to early winter.
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: 08/31/2025 - 11/29/2025
: 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 : 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 : 5 <5 <5 <5 <5 <5
:Missouri River
Williston 22.0 24.0 26.0 : <5 5 <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 : 9 10 <5 <5 <5 <5
:Beaver Creek
Linton 12.0 14.0 16.0 : <5 9 <5 7 <5 5
:Little Muddy River
Williston 10.0 12.0 14.0 : <5 20 <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 10 <5 6 <5 5
:Knife River
Hazen 21.0 24.0 25.0 : 8 9 <5 7 <5 6
:Heart River
Mandan 27.0 33.0 38.0 : <5 <5 <5 <5 <5 <5
:Apple Creek
Menoken 15.0 16.0 17.0 : 9 14 7 11 <5 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: 08/31/2025 - 11/29/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.5 5.5 5.5 5.5 5.6 7.8 11.4
:James River
Grace City 5.0 5.0 5.0 5.0 5.2 7.1 12.5
LaMoure 9.1 9.1 9.1 9.1 9.3 10.4 14.3
:Missouri River
Williston 15.0 15.0 15.1 15.1 15.4 15.8 17.9
:Cannonball River
Regent 5.0 5.1 5.2 6.1 7.1 8.0 8.7
:Cedar Creek
Raleigh 1.1 1.1 1.2 2.6 4.3 5.8 7.0
:Cannonball River
Breien 2.3 2.4 2.5 4.2 6.7 9.6 12.4
:Beaver Creek
Linton 4.6 4.6 4.6 5.1 6.9 8.7 11.1
:Little Muddy River
Williston 4.5 4.5 4.5 4.5 5.2 7.5 9.6
:Little Missouri River
Marmarth 1.0 1.0 1.0 1.0 2.4 5.7 6.6
Medora 2.0 2.0 2.0 2.0 3.3 6.2 7.1
Watford City 7.1 7.1 7.1 7.3 9.8 11.5 12.3
:Knife River
Manning 6.3 6.3 6.3 6.4 8.0 10.0 14.0
:Spring Creek
Zap 4.7 4.7 4.7 4.7 5.8 10.6 14.2
:Knife River
Hazen 0.6 0.6 0.6 1.7 4.9 17.4 22.9
:Heart River
Mandan 9.6 9.6 9.6 9.6 11.6 22.6 25.4
:Apple Creek
Menoken 5.6 5.6 5.6 5.7 6.4 13.9 16.7
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: 08/31/2025 - 11/29/2025
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 4.9 4.7 4.7 4.7 4.7 4.7 4.7
:James River
Grace City 4.5 4.2 4.0 4.0 4.0 4.0 4.0
LaMoure 8.0 7.3 7.1 6.9 6.8 6.8 6.8
:Missouri River
:Cannonball River
Regent 4.8 4.7 4.7 4.7 4.7 4.7 4.7
:Cedar Creek
Raleigh 0.9 0.9 0.9 0.9 0.8 0.8 0.8
:Cannonball River
Breien 2.3 2.2 2.2 2.2 2.2 2.2 2.2
:Beaver Creek
Linton 4.5 4.5 4.5 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 1.0 1.0 1.0 1.0 1.0 0.9 0.9
Medora 2.0 2.0 2.0 2.0 2.0 2.0 2.0
Watford City 7.1 7.1 7.1 7.0 7.0 7.0 7.0
:Knife River
Manning 6.3 6.2 6.2 6.2 6.2 6.2 6.2
:Spring Creek
Zap 4.7 4.7 4.7 4.7 4.7 4.7 4.7
:Knife River
Hazen 0.6 0.6 0.6 0.5 0.5 0.5 0.5
:Heart River
Mandan 9.4 9.2 9.0 9.0 9.0 9.0 9.0
:Apple Creek
Menoken 5.4 5.4 5.4 5.4 5.4 5.4 5.4
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