Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
101
FGUS73 KBIS 292102
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-300515-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
302 PM CST Fri Nov 29 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 30 November
through 28 February, 2025. 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 of the Missouri and
James rivers are in the lower range of normal to near single digit
percentiles for this time of year. Similarly, some of these smaller
streams with minimal flow have been gaining ice cover over the past
couple weeks, thus far with no problems.
...Missouri and Yellowstone Rivers...
Streamflow on both the Yellowstone and Missouri rivers are at the
lower end of normal for this time of year. Water temperatures have
plummeted as of late, and while a warming trend is expected in early
December, one should expect ice formation to commence on the
Missouri and Yellowstone rivers over the coming weeks.
...Snowpack Conditions...
Overall, the Missouri and James River basins of North Dakota have
entered their snow accumulation seasons. While warmer weather,
including daytime highs above freezing, are expected early in
December, this does not necessarily mean those areas with
appreciable snow will lose their snowpack. In general, a trace to
near an inch of water equivalent can be found locally depending on
your location, with the higher amounts being in the upper James
River Basin.
...Current Drought Conditions...
The onset of the snow accumulation season has slowed the spread and
degradation of drought conditions across North Dakota, but has not
yet resulted in significant improvements.
...Reservoirs and Natural Wetlands...
Streamflow, natural wetlands and small water features range from
well below normal to the lower range of normal for this time of year.
...Soil Conditions...
Soil moisture values remain well below normal for this time of year,
especially west of Highway 83. This is not expected to experience
much change now that the region is out of the growing season and
soil temperatures are now widely below freezing, which would inhibit
infiltration of any liquid moisture on the ground.
...Weather Outlook...
The near term 6-10 and 8-14 day outlooks generally favor above normal
temperatures and above normal chances for precipitation. The longer
term 3-4 week outlooks reflect an equal chances designation for
above normal, near normal, or below normal temperatures but retains
the expectation for above normal precipitation. Overall though, the
one-month outlook for December has the entire state of North Dakota
in the equal chances designation for both temperature and
precipitation. Looking even farther in the future, the three-month
outlooks for December, January, and February favor below normal
temperatures with an equal chances designation for above normal,
near normal, or below normal precipitation.
...Ice Conditions...
Smaller streams and rivers have been gaining ice cover over the past
couple of weeks. This trend should continue and larger streams, such
as the Missouri and Yellowstone are likely to see ice formation over
the first few weeks of December.
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: 11/30/2024 - 02/28/2025
: 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 : <5 8 <5 <5 <5 <5
:Beaver Creek
Linton 12.0 14.0 16.0 : <5 <5 <5 <5 <5 <5
:Little Muddy River
Williston 10.0 12.0 14.0 : <5 <5 <5 <5 <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 <5 <5 <5 <5 <5
:Spring Creek
Zap 14.0 18.0 20.0 : <5 <5 <5 <5 <5 <5
:Knife River
Hazen 21.0 24.0 25.0 : <5 <5 <5 <5 <5 <5
:Heart River
Mandan 27.0 33.0 38.0 : <5 <5 <5 <5 <5 <5
:Apple Creek
Menoken 15.0 16.0 17.0 : <5 <5 <5 <5 <5 <5
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: 11/30/2024 - 02/28/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.6 5.6 5.6 5.6 5.6 8.7 10.0
:James River
Grace City 4.3 4.3 4.3 4.3 4.5 5.0 8.3
LaMoure 7.7 7.7 7.7 7.7 7.7 7.8 11.0
:Missouri River
Williston 15.4 15.4 15.4 15.4 15.5 15.8 16.2
:Cannonball River
Regent 5.2 5.2 5.2 5.2 5.6 6.2 6.3
:Cedar Creek
Raleigh 0.2 0.3 1.2 1.9 2.9 3.5 4.2
:Cannonball River
Breien 2.0 2.7 2.9 3.6 5.0 5.9 7.6
:Beaver Creek
Linton 4.5 4.5 4.5 4.8 5.0 5.3 5.7
: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 1.2 1.4
Medora 1.4 1.4 1.4 1.4 1.4 1.4 1.8
Watford City 7.0 7.0 7.0 7.0 7.0 7.1 7.3
:Knife River
Manning 6.1 6.1 6.1 6.1 6.1 6.1 6.1
:Spring Creek
Zap 4.8 4.8 4.8 4.8 4.8 4.8 4.8
:Knife River
Hazen 0.8 0.8 0.8 0.8 0.8 1.1 1.4
:Heart River
Mandan 9.1 9.1 9.2 9.4 10.0 10.7 11.5
:Apple Creek
Menoken 5.0 5.0 5.0 5.5 6.5 9.0 12.1
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: 11/30/2024 - 02/28/2025
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.2 5.2 5.1 5.1 5.1 5.1 5.1
:James River
Grace City 4.3 4.3 4.3 4.3 4.3 4.3 4.3
LaMoure 7.6 7.6 7.6 7.6 7.6 7.6 7.6
:Missouri River
:Cannonball River
Regent 5.2 5.2 5.2 5.2 5.2 5.2 5.2
:Cedar Creek
Raleigh 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Cannonball River
Breien 1.9 1.9 1.9 1.9 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 4.4 4.4 4.4 4.4 4.4 4.4 4.4
:Little Missouri River
Marmarth 1.1 1.1 1.1 1.1 1.1 1.1 1.1
Medora 1.3 1.3 1.3 1.3 1.3 1.3 1.3
Watford City 6.9 6.9 6.9 6.9 6.9 6.9 6.9
:Knife River
Manning 6.1 6.1 6.1 6.1 6.1 6.1 6.1
:Spring Creek
Zap 4.8 4.8 4.8 4.8 4.8 4.8 4.8
:Knife River
Hazen 0.7 0.7 0.7 0.7 0.7 0.7 0.7
:Heart River
Mandan 9.1 9.1 9.1 9.1 9.1 9.1 9.1
:Apple Creek
Menoken 4.8 4.8 4.7 4.1 4.0 4.0 4.0
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 December.
$$
Schlag