Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
606
FGUS73 KBIS 251853
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-271800-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
153 PM CDT Thu Apr 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 April
through 26 July, 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...
Going into late spring, the region has escaped the normal spring
flood season from melting snow. Flood risks generally remain below
to near normal for this time of year and should be considered
directly related to the region entering its summer severe weather
season where large thunderstorms become increasingly common. Indeed,
at this point one should expect a few occurrences of minor to
moderate river floods somewhere in North Dakota through late summer
even though drought concerns will most likely be at the forefront of
many residents` thoughts.
...Missouri and Yellowstone Rivers...
The snowpack along the Missouri and Yellowstone rivers in western
North Dakota and on up through the Montana headwaters for both
streams peaked in early April at a value just above the least
observed over the past 30 years. This certainly suggests that
overall runoff along the Missouri and Yellowstone rivers will fall
well short of normal, and that alone will provide challenges for
those who maintain and regulate the water levels at lakes Oahe,
Sakakawea, and Fort Peck. That being said, a planned "Test Flow" out
of Fort Peck is expected to briefly raise water levels along the
Missouri River above Sakakawea. Given the currently modest amount of
water coming down the Yellowstone, this is not likely to create
concerns.
...Snowpack Conditions...
No snowpack exists within either the Missouri or James River basins
of North Dakota.
...Current Drought Conditions...
Timely, but not necessarily plentiful rains over the past few weeks
have trimmed the extent and somewhat improved drought conditions.
However, without continued timely rains, drought concerns persist
and this trend of improvement may be short-lived.
...Reservoirs and Natural Wetlands...
Most natural wetlands and smaller man-made water supply features are
doing well despite an overall snow deficit across the state this
winter. Most rivers and streams are at the lower end of normal for
this time of year. The exceptions to this are in the very southwest
and very northeastern part of the state where several stream gages
are in the 10th to 24th percentile, and even a few streams are below
the 10th percentile.
...Soil Conditions...
Soil moisture values across the Missouri and James basins are
a mixture of somewhat above normal in parts of western and central
North Dakota, to well below normal in parts of the James River basin
and eastern North Dakota.
...Weather Outlook...
Near term, as in the next few days, rain is expected over most of
North Dakota. This should put the region on track to enter May with
at least a stable position on the drought front. The 6-10 and 8-14
day outlooks favor an above normal temperature and precipitation
pattern. The strenth of this above normal temperature and
precipitation pattern slightly wanes in the weeks 3-4 outlooks
before all of the Missouri and James River basins of North Dakota
slide into the equal chances category for above normal, near normal,
or below normal temperature and precipitation for the entirety of
May and again in the 3-month outlook for May, June and July.
...Ice Conditions...
No ice is known to exist 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: 04/27/2024 - 07/26/2024
: 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 : 5 <5 <5 <5 <5 <5
LaMoure 14.0 16.0 18.0 : 9 5 7 <5 <5 <5
:Missouri River
Williston 22.0 24.0 26.0 : 8 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 : 15 38 <5 <5 <5 <5
:Beaver Creek
Linton 12.0 14.0 16.0 : 11 31 6 19 <5 13
:Little Muddy River
Williston 10.0 12.0 14.0 : 14 60 7 30 <5 8
:Little Missouri River
Marmarth 18.0 23.0 30.0 : <5 6 <5 <5 <5 <5
Medora 15.0 18.0 20.0 : <5 18 <5 8 <5 6
Watford City 20.0 24.0 30.0 : <5 9 <5 5 <5 <5
:Knife River
Manning 15.0 17.0 20.0 : <5 17 <5 <5 <5 <5
:Spring Creek
Zap 14.0 18.0 20.0 : 10 19 6 12 5 11
:Knife River
Hazen 21.0 24.0 25.0 : 10 19 5 16 <5 9
:Heart River
Mandan 27.0 33.0 38.0 : 5 9 <5 <5 <5 <5
:Apple Creek
Menoken 15.0 16.0 17.0 : 30 52 17 41 6 19
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: 04/27/2024 - 07/26/2024
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.6 5.6 5.6 6.0 7.4 9.5 10.6
:James River
Grace City 4.7 4.7 4.7 5.0 6.6 7.7 11.3
LaMoure 7.7 7.7 7.7 8.2 9.3 12.5 17.7
:Missouri River
Williston 17.2 17.5 18.2 19.2 19.6 21.6 23.0
:Cannonball River
Regent 5.4 5.4 5.7 6.8 7.4 8.3 9.6
:Cedar Creek
Raleigh 1.4 2.4 3.0 4.1 5.3 6.3 7.4
:Cannonball River
Breien 2.6 3.3 5.1 6.8 8.8 11.0 11.9
:Beaver Creek
Linton 5.0 5.1 5.3 6.2 9.6 12.4 14.4
:Little Muddy River
Williston 4.8 4.8 4.9 6.5 8.1 10.9 12.2
:Little Missouri River
Marmarth 1.1 1.1 1.1 1.5 3.3 7.2 9.5
Medora 1.7 1.7 1.7 2.4 5.5 7.6 10.1
Watford City 7.2 7.2 7.2 8.2 10.1 12.3 13.8
:Knife River
Manning 6.4 6.4 6.4 8.1 9.2 10.9 11.6
:Spring Creek
Zap 4.8 4.8 4.9 6.4 7.8 14.4 19.9
:Knife River
Hazen 1.4 1.4 2.5 6.0 10.2 21.2 23.7
:Heart River
Mandan 10.7 10.7 11.4 14.5 18.7 23.8 27.6
:Apple Creek
Menoken 5.8 5.8 5.8 10.7 15.3 17.0 18.0
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: 04/27/2024 - 07/26/2024
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 5.1 5.1 5.1 5.1 5.1 5.1 5.1
:James River
Grace City 4.6 4.6 4.5 4.5 4.5 4.5 4.5
LaMoure 7.7 7.7 7.5 7.3 7.2 7.2 7.2
:Missouri River
:Cannonball River
Regent 5.3 5.3 5.3 5.3 5.2 5.2 5.2
:Cedar Creek
Raleigh 1.2 1.2 1.1 1.1 1.0 1.0 0.9
:Cannonball River
Breien 2.4 2.3 2.3 2.2 2.1 2.1 2.1
:Beaver Creek
Linton 4.9 4.8 4.8 4.8 4.8 4.8 4.8
:Little Muddy River
Williston 4.7 4.7 4.7 4.7 4.7 4.7 4.7
:Little Missouri River
Marmarth 1.0 1.0 1.0 0.9 0.9 0.8 0.8
Medora 1.5 1.5 1.5 1.4 1.4 1.4 1.4
Watford City 7.1 7.1 7.1 7.0 7.0 7.0 7.0
:Knife River
Manning 6.3 6.3 6.2 6.1 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 1.1 1.1 0.9 0.9 0.8 0.8 0.8
:Heart River
Mandan 10.3 10.0 9.9 9.8 9.8 9.7 9.7
:Apple Creek
Menoken 5.1 5.0 4.3 3.9 3.4 3.3 3.2
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 May.
$$
Schlag