Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
180
FGUS73 KBIS 251416
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-252230-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
916 AM CDT Thu Jul 25 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 27 July
through 25 October, 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...
There is nothing alarming in the below probabilities for flooding
within the Missouri and James River basins of North Dakota. The risk
for flooding at NWS forecast locations is near normal to slightly
below normal for this time of year. Coming out of winter, a lack of
snow for spring runoff raised concerns for widespread drought. For
the most part, this has been limited to the very southwest corner of
North Dakota as ample and timely rains across most of the Missouri,
and particularly the James River basin, have warded off increased
drought designations. Streamflow on most of the smaller rivers and
streams has remained adequate to abundant, all while examples of
flooding have been at a minimum.
...Missouri and Yellowstone Rivers...
Above normal spring and early summer rains have largely made up for
deficits in winter snowpack. Indeed, both the Yellowstone and
Missouri rivers have fared much better than expected this summer.
Now that very little runoff is generated in the mountainous
headwaters of Montana, water levels along the Missouri and
Yellowstone west of Williston have fallen to roughly normal water
levels for this time of the year. Nonetheless, Missouri River
mainstem reservoirs of Lake Sakakawea and Lake Oahe are higher than
expected even as Sakakawea has likely peaked for the summer, and
Oahe continues to rise.
...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 continues to keep
drought restricted to the southwest corner of North Dakota. Recent
warm and dry weather is combining with the end of the cool weather
native grasses growing season to enhance the perception of
increasingly dry conditions. Overall though, the state is in much
better shape with respect to drought designations than one would
have expected just a few short months ago. Native vegetation,
pastures, and crops seem to be doing very well this 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, 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, 8-14, and weeks 3-4 outlooks continue to
reflect a strong favoring for above normal temperatures and below
normal precipitation. Looking longer term at the one-month and
three-month outlooks covering August through October start to show a
waning of the strong signal for above normal temperatures and below
normal 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.
...Table 1--Probabilities for minor...moderate and major flooding...
Valid Period: 07/27/2024 - 10/25/2024
: 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 : 6 8 5 6 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 27 <5 13 <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 : 17 24 <5 <5 <5 <5
:Beaver Creek
Linton 12.0 14.0 16.0 : 5 16 <5 10 <5 8
:Little Muddy River
Williston 10.0 12.0 14.0 : <5 23 <5 10 <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 11 <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 : 7 12 <5 10 <5 9
:Heart River
Mandan 27.0 33.0 38.0 : <5 7 <5 <5 <5 <5
:Apple Creek
Menoken 15.0 16.0 17.0 : 16 33 11 24 5 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: 07/27/2024 - 10/25/2024
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 6.3 6.3 6.3 6.3 8.1 9.8 11.2
:James River
Grace City 6.0 6.0 6.0 6.0 7.1 7.8 14.0
LaMoure 9.4 9.6 9.6 9.6 9.7 9.7 13.1
:Missouri River
Williston 15.4 15.4 15.4 15.4 15.4 17.0 18.3
:Cannonball River
Regent 5.1 5.2 5.3 6.0 7.8 9.7 10.0
:Cedar Creek
Raleigh 1.0 1.0 1.2 3.2 5.6 7.1 8.2
:Cannonball River
Breien 2.1 2.2 2.3 5.2 9.1 12.6 14.0
:Beaver Creek
Linton 4.6 4.6 4.7 5.2 6.9 9.1 11.6
:Little Muddy River
Williston 4.7 4.7 4.7 4.7 5.0 5.7 8.7
:Little Missouri River
Marmarth 1.1 1.1 1.1 1.1 1.4 4.3 4.6
Medora 1.6 1.6 1.6 1.7 2.2 4.6 4.8
Watford City 7.1 7.1 7.2 7.2 8.5 10.3 11.0
:Knife River
Manning 6.3 6.3 6.3 6.3 6.6 10.5 13.4
:Spring Creek
Zap 4.8 4.8 4.8 4.8 5.3 10.2 12.5
:Knife River
Hazen 0.6 0.6 0.7 0.7 4.8 17.6 22.2
:Heart River
Mandan 9.1 9.1 9.1 9.2 13.7 22.8 26.4
:Apple Creek
Menoken 4.1 4.1 4.1 5.1 11.5 16.1 17.1
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: 07/27/2024 - 10/25/2024
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.5 5.3 5.1 5.1 5.1 5.1 5.1
:James River
Grace City 4.9 4.9 4.8 4.8 4.8 4.8 4.8
LaMoure 8.3 7.9 7.8 7.8 7.8 7.8 7.7
:Missouri River
:Cannonball River
Regent 4.9 4.9 4.9 4.9 4.9 4.9 4.9
:Cedar Creek
Raleigh 0.6 0.6 0.6 0.6 0.6 0.6 0.6
:Cannonball River
Breien 1.9 1.9 1.9 1.9 1.9 1.9 1.9
:Beaver Creek
Linton 4.4 4.4 4.3 4.3 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 0.9 0.9 0.9 0.9 0.9 0.9 0.9
Medora 1.4 1.4 1.4 1.4 1.4 1.4 1.4
Watford City 7.0 7.0 7.0 7.0 7.0 7.0 7.0
:Knife River
Manning 6.0 6.0 6.0 6.0 6.0 6.0 6.0
: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 8.0 8.0 8.0 8.0 8.0 8.0 8.0
:Apple Creek
Menoken 3.8 3.7 3.7 3.6 3.5 3.5 3.4
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 August.
$$
Schlag