Flood Potential Outlook
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
772
FGUS73 KUNR 132032
ESFUNR
SDC007-019-033-047-055-063-071-081-093-095-102-103-105-121-123-137-
WYC005-011-045-250000
Probabilistic Hydrologic Outlook
National Weather Service Rapid City SD
232 PM MDT Thu Mar 13 2025
...Spring Flood and Water Resource Outlook...
...Below-Average Flood Potential This Spring...
This spring flood and water resource outlook is for the Rapid City
Hydrologic Service Area (HSA), which covers northeastern Wyoming and
western South Dakota. The main river basins include the Little
Missouri, eastern Powder, Belle Fourche, Grand, Moreau, Cheyenne,
Bad, White, and Keya Paha.
.Flood Outlook Summary...
The flood potential this spring is below average across all of
northeastern Wyoming and western South Dakota.
.Snow Cover and Liquid Water Content...
Snow depth is zero or near zero across most of the area. The
exceptions are across the northern Black Hills, mainly the higher
elevations, where there still is anywhere from a few inches to near
20 inches of snow depth. The highest elevations of the Bear Lodge
Mountains also have up to 6 inches of snow depth. The liquid water
content in these areas range mostly from 1 to 6 inches.
.Soil Conditions and Frost Depths...
Soil moisture is below average across all of the area and frost
depths are generally zero, with the exception being some lingering
frost over the Black Hills.
.Lake and River Conditions...
Rivers and Creeks across the area are generally ice free after the
warm conditions of the last few weeks. Many lakes on the plains
are mostly ice free, though Shadehill Reservoir still has some thin
ice. Lakes across the Black Hills are still mostly ice covered, but
quickly thinning.
.Weather Outlooks...
The precipitation outlook for spring through summer favors drier
than average conditions, especially during the late spring and
summer. The temperature outlook for spring through summer favors
near-to-above average temperatures. These outlooks are consistent
with the decay of La Nia followed by near-average eastern Pacific
Ocean temperatures. In summary, drought conditions are expected to
persist.
.Probablistic Outlook...
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: 3/15/2025 - 9/30/2025
: 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
-------- ----- ----- ----- : --- --- --- --- --- ---
:Little Missouri River
Camp Crook 12.0 17.0 19.0 : 17 41 <5 20 <5 6
:Moreau River
Faith 16.0 18.0 21.0 : <5 21 <5 12 <5 <5
:Belle Fourche River
WY-SD State Line 15.0 16.0 18.0 : <5 16 <5 <5 <5 <5
:South Belle Fourche River
Sturgis 15.0 17.0 19.0 : 20 26 16 18 7 9
:Belle Fourche River
Elm Springs 19.0 22.0 24.0 : 9 16 <5 <5 <5 <5
:Cheyenne River
Wasta 13.0 15.0 16.0 : <5 7 <5 <5 <5 <5
Plainview 17.0 19.0 20.0 : 27 45 16 27 12 17
:Bad River
Midland 21.0 24.0 25.0 : 19 36 <5 5 <5 <5
:White River
Kadoka 15.0 16.0 19.0 : 22 53 18 45 6 19
White River 14.0 15.0 17.0 : 25 47 20 39 16 25
Oacoma 15.0 20.0 25.0 : 56 75 8 24 <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: 3/15/2025 - 9/30/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Little Missouri River
Camp Crook 2.5 2.5 2.7 4.7 8.2 14.2 15.2
:Moreau River
Faith 3.0 4.7 8.5 10.6 13.1 14.8 15.7
:Belle Fourche River
WY-SD State Line 4.4 4.4 4.7 6.8 9.7 12.9 14.3
:South Belle Fourche River
Sturgis 4.0 4.3 5.7 7.7 12.7 17.2 19.7
:Belle Fourche River
Elm Springs 5.2 5.4 7.3 9.0 14.1 18.5 20.9
:Cheyenne River
Wasta 0.5 0.7 1.5 3.8 5.4 6.3 7.6
Plainview 9.2 9.6 11.0 13.5 17.6 20.2 21.0
:Bad River
Midland 4.4 4.8 6.7 12.5 19.0 22.6 22.9
:White River
Kadoka 7.4 7.5 9.8 13.9 14.9 17.6 25.2
White River 6.9 7.1 9.4 12.5 14.0 17.3 24.0
Oacoma 10.2 10.9 13.6 15.3 17.8 19.2 22.7
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: 3/15/2025 - 9/30/2025
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Little Missouri River
Camp Crook 2.2 2.2 2.1 2.0 1.8 1.7 1.6
:Moreau River
Faith 1.5 1.4 1.4 1.4 1.4 1.4 1.4
:Belle Fourche River
WY-SD State Line 3.2 3.2 3.2 3.1 3.0 3.0 3.0
:South Belle Fourche River
Sturgis 2.2 2.2 2.2 2.2 2.2 2.1 2.1
:Belle Fourche River
Elm Springs 3.9 3.8 3.8 3.8 3.8 3.8 3.8
:Cheyenne River
Wasta 0.3 0.3 0.2 0.2 0.1 0.1 0.1
Plainview 8.4 8.3 8.3 8.3 8.3 8.2 8.2
:Bad River
Midland 2.6 2.6 2.6 2.6 2.6 2.6 2.6
:White River
Kadoka 4.0 4.0 3.9 3.6 3.6 3.6 3.6
White River 3.4 3.3 3.3 3.1 3.0 3.0 3.0
Oacoma 7.3 7.3 7.2 7.0 6.6 6.5 6.5
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/unr for more weather and water
information.
.Outlook Schedule...
This is the last planned spring flood outlook for the season.
$$
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