Flood Potential Outlook
Issued by NWS North Platte, NE
Issued by NWS North Platte, NE
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Probabilistic Hydrologic Outlook
National Weather Service North Platte NE
126 PM CST Thu Feb 27 2025
...Spring Flood and Water Resource Outlook Number 2...
...A Below Average Flood Potential from Ice Jams and Spring
Snowmelt...
This Spring Flood and Water Resource Outlook is for the North
Platte Hydrologic Service Area, which covers western and north
central Nebraska. The river basins include: the North Platte
and South Platte Rivers and the Platte River in western Nebraska,
Frenchman Creek and Stinking Water Creek in southwest Nebraska,
the Loup and Dismal Rivers in the Sandhills of Nebraska, and
portions of the Elkhorn and Niobrara Rivers in north central
Nebraska.
.Flood Outlook Summary...
A below average flood potential is expected from ice jamming. Above
normal temperatures the last week in February have resulted in
rivers becoming partial ice covered to ice free. Above normal
temperatures are forecast to become slighty below normal the first
week of March.
A below average flood potential is expected from spring snowmelt. It
was a very dry winter through January, followed by 6 to 12 inches of
snowfall during the month of February. Due to recent warm
temperatures, all snow cover has melted.
The potential for rainfall induced flash flooding is not quantifiable.
This type of flooding is most likely to occur during the late spring
and summer months.
.Snow Cover and Mountain Snowpack...
As of February 27th, no snow cover existed across north central
Nebraska. March and April are typically snowy months, so additional
snowfall is possible.
Snowpack conditions in the North Platte and South Platte River
Basins in Colorado and Wyoming are currently near average. Snow
water equivalents ranged from near 100 percent of average for the
North Platte Basin and 105 percent of average for the South Platte
Basin. These values are slightly higher than last year. A below
average flood potential is expected from mountain snowmelt runoff.
.Reservoir Conditions...
Normal operations are ongoing at reservoirs along the North Platte
River for this time of year. Releases from these dams have been
limited through the winter months, with inflows generally coming
from melting snow. Because of these operations, reservoir levels
have risen though the winter months. The current reservoir storage
across Wyoming, as well as Lake McConaughy, are below average for
this time of year.
.Soil Conditions and Frost Depths...
Soil moisture was much below normal across much of western and north
central Nebraska. According to the U.S. Drought Monitor, abnormally
dry to moderate drought conditions existed across southwestern
Nebraska with severe to extreme drought conditions across the
remainder of western and north central Nebraska. Soil temperature
sensors indicate no frost exists at 4 inches as 4 inch soil
temperatures range from 32 to 38 degrees. Some frost remains however
in the top 2 inches.
.River and Lake Ice Conditions...
Monthly average streamflow was average to above average across the
central and northern Sandhills, including the Niobrara, Elkhorn and
Loup River Basins. Average to below average streamflow was indicated
across the southeast panhandle and southwest Nebraska, including the
Platte River Basin, and Frenchman Creek Basin. Lakes and rivers
remained partial frozen to ice free.
.Seasonal Precipitation...
Precipitation so far this water year, since October 1, 2024, was
much below normal. Precipitation ranged from 1 to around 4 inches,
to as little as a half inch in small portions of Sheridan and
western Cherry County. These values are from 25 percent to around 75
percent of normal across north central and central Nebraska, to 90
to 120 percent of normal across portions of southwest Nebraska.
.Weather Outlooks...
Water temperatures in the tropical Pacific Ocean remain slightly
below average, with weak La Nina conditions. The outlook indicates a
66 percent chance that neutral conditions may develop March through
May. For the late winter and spring months, this weather pattern
will typically favor near normal temperatures with near to slightly
below normal precipitation across the Central Plains.
According to the Climate Prediction Center, the latest 8 to 14 day
outlook calls for above average temperatures with near average
precipitation.
The latest 30 day outlook for March calls for near average
temperatures and precipitation.
The latest 90 day outlook for March, April and May favors near
average temperatures with near to below average precipitation going
into this spring.
.Numerical Weather Outlooks...
For the Frenchman Creek, North Platte, South Platte, Platte,
Elkhorn, and Niobrara Rivers...long range probabilistic outlooks
are issued for the water year from December through May. All other
months and locations are 90 day probabilistic outlooks.
In Table 1 below...the current (CS) and historical (HS) or normal
probabilities of exceeding minor...moderate...and major flood stages
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 more 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: 03/01/2025 - 05/30/2025
: 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
-------- ----- ----- ----- : --- --- --- --- --- ---
:North Platte River
Lisco 4.0 5.0 6.0 : <5 8 <5 <5 <5 <5
Lewellen 8.0 9.0 10.0 : 8 11 <5 <5 <5 <5
North Platte 6.0 6.5 7.0 : 6 15 5 13 5 11
:South Platte River
Roscoe 9.0 11.0 13.0 : 9 9 8 8 6 7
North Platte 13.0 14.0 15.0 : 8 8 7 7 <5 <5
:Elkhorn River
Ewing 1N 9.0 10.0 12.0 : <5 <5 <5 <5 <5 <5
:Platte River
Brady North Chann 7.5 9.0 11.0 : 13 26 8 15 5 7
:Frenchman Creek
Palisade 7.0 8.0 9.0 : 6 10 <5 <5 <5 <5
:Stinking Water Creek
Palisade 2NW 10.0 11.0 12.0 : <5 <5 <5 <5 <5 <5
:Niobrara River
Sparks 6.0 12.0 16.0 : <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: 03/01/2025 - 05/30/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:North Platte River
Lisco 1.3 1.3 1.3 1.4 1.9 3.0 3.5
Lewellen 6.0 6.0 6.0 6.0 6.4 7.9 8.1
North Platte 4.6 4.6 4.6 4.6 4.7 5.3 6.6
:South Platte River
Roscoe 4.0 4.1 4.3 5.2 7.5 8.7 13.4
North Platte 6.9 7.0 7.0 7.8 10.1 11.1 14.6
:Elkhorn River
Ewing 1N 1.3 1.3 1.8 3.3 4.2 5.5 6.1
:Platte River
Brady North Chann 2.4 2.5 2.6 4.3 6.5 7.9 10.9
:Frenchman Creek
Palisade 3.2 3.2 3.3 3.8 4.8 6.6 7.3
:Stinking Water Creek
Palisade 2NW 2.8 2.8 3.0 3.4 3.9 5.7 6.6
:Niobrara River
Sparks 2.8 2.9 3.0 3.1 3.3 3.4 3.8
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: 03/01/2025 - 05/30/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:North Platte River
Lisco 1.2 1.1 1.1 1.0 0.9 0.9 0.9
Lewellen 5.3 5.2 5.1 4.8 4.7 4.7 4.7
North Platte 4.5 4.4 4.3 4.3 4.3 4.3 4.2
:South Platte River
Roscoe 3.2 3.0 2.4 2.3 2.3 2.3 2.3
North Platte 6.7 6.7 6.7 6.7 6.7 6.7 6.6
:Elkhorn River
Ewing 1N 1.3 1.3 1.3 1.3 1.3 1.3 1.3
:Platte River
Brady North Chann 2.4 2.4 2.4 2.4 2.4 2.4 2.4
:Frenchman Creek
Palisade 3.2 3.2 3.2 3.2 3.1 3.1 3.1
:Stinking Water Creek
Palisade 2NW 2.7 2.6 2.6 2.5 2.3 2.2 2.1
:Niobrara River
Sparks 2.8 2.8 2.8 2.8 2.7 2.7 2.7
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/lbf for more weather and water
information.
This is the second spring flood and water resource outlook for 2025.
The next spring flood outlook will be issued March 13th.
Roberg