SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE
MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL, MO
MARCH 2, 2017
THIS SPRING OUTLOOK IS FOR THE MISSOURI RIVER DRAINAGE WHICH
INCLUDES RIVERS IN MONTANA, WYOMING, COLORADO, NORTH AND SOUTH
DAKOTA, NEBRASKA, KANSAS, IOWA, MINNESOTA AND MISSOURI.
SPRING FLOOD OUTLOOK
Flood risk this spring can be generally categorized as near
normal for most of the Missouri River Basin. Exceptions being
isolated pockets in the mountainous west, where an above normal
risk for flooding exists. Also, North Dakota, eastern South
Dakota, and northwest Iowa have an enhanced risk for flooding
as compared to normal. The state of Missouri has a below
normal risk for flooding this spring as compared to normal. A
near normal risk for flooding simply indicates that locations
which typically experience springtime flooding may flood again
this year. And those locations which typically do not
experience flooding in the spring are not projected to
experience flooding this year. Having an above normal risk for
flooding does not necessarily mean flooding is likely.
Likewise, areas having a less than normal risk for flooding can
still be projected to reach flood stage, albeit at a diminished
risk as compared to normal.
Overall a somewhat above average snowpack exists in the
mountainous west. Widespread significant flooding in the
mountainous west is not likely due to snowmelt alone. However,
low elevation melt aggravated by river ice has already resulted
in tributary flooding in the Milk River Basin in Montana, and
along the Bighorn River in Wyoming. Minor flooding is possible
this spring along the Sun River, Clear Creek, and Clarks Fork of the
Yellowstone River in Montana. Minor to possibly moderate
flooding is projected in the Wind River Basin in Wyoming.
Plains snowpack is widespread, but generally shallow. Largest
estimates of snow water equivalent exist in the headwaters of
the James River Basin in North Dakota. Wetter than normal soils
exist in eastern Montana, North Dakota, eastern South Dakota, and
western Iowa. Frozen ground is not a factor for plains runoff
enhancement this year. It should be remembered that springtime
flooding in the lower third of the basin is primarily driven by
convective activity. Current and expected conditions make
flooding across many areas of the plains likely this spring.
In North Dakota: unseasonably warm temperatures over the last
half of February eroded much of the above average snowpack.
However, runoff response was not as high as expected. Possible
reasons may have included sublimation of the snowpack, and drier
than assumed soil moisture conditions. Minor flooding remains a
possibility along the Cannonball and Little Muddy Rivers.
Moderate flooding is possible in the headwaters of the James
In South Dakota: snowmelt aggravated by river ice has led to
minor flooding along the White River. Snowmelt has also resulted
in minor flooding along the James River. Minor flooding remains
likely this spring along the James, White, and Big Sioux Rivers.
In Nebraska: minor flooding is possible along the lower reach of
the North Platte River, and along some of the smaller streams in
the eastern portion of the state, particularly Wahoo and Salt
Creeks. The Platte River in western Nebraska will be closely
monitored, given the above average snowpack in the North Platte
headwaters, and current reservoir conditions. Although long
range river models still do not suggest that flooding along the
Platte is likely, conditions can change quickly.
In Iowa: flooding has already occurred this season in the Little
Sioux River Basin due to snowmelt. Minor flooding will continue
to be likely along the Little Sioux, as well as along the Rock
and Floyd Rivers. Minor-to-moderate flooding is possible within
the Big Sioux River Basin.
In Kansas: minor flooding is possible in the southern portion of
the Big Blue Basin, as well as in the Osage River Basin.
Moderate flooding is possible along Stranger Creek.
In Missouri: minor flooding is possible within the Platte,
Osage, and Chariton River Basins, and along many of the smaller
tributaries to the Missouri River. Moderate flooding is possible
in the Grand River Basin, and along the Tarkio River.
Mainstem Missouri River below Gavins Point Dam: minor flooding is
possible along the Missouri River downstream of Nebraska City to
its confluence with the Mississippi River, given normal springtime
This outlook contains a generalized summary of spring flood
potential. Above normal future snow accumulations, combined with
heavy rains and rapid melt, will increase the current flood potential,
while below normal future precipitation, and gradual or intermittent
freezing and thawing, will decrease the magnitude of the current
assessment. In addition, when many of the frozen rivers and streams thaw, ice jams can occur, causing higher river levels and possible flooding. Ice jams have already been reported this season. Most reports have indicated that the impacts have been relatively minor and localized in extent. High water due to river ice has been
reported along Ponca Creek, the Little Blue River, the lower reach
of the North Platte River, and the Platte River in Nebraska, the
Madison, Tongue, Gallatin, and Bighorn Rivers in Montana, and in
the Wind and Bighorn Basins in Wyoming. Additional ice jams are
possible throughout the late winter and early spring.
These projections of river stages and reservoir levels are based on
current observed states of streamflow, soil moisture, and snowpack,
coupled with future precipitation and temperature patterns, and
anticipated operational hydrologic changes, such as reservoir
releases and canal diversions. "Outlooks" are provided for
long-range (weeks to months) projections based on climatological
patterns of precipitation and temperature. "Forecasts" are provided
for short-term (days) projections based on forecast patterns of
precipitation and temperature. The uncertainty of these products
varies from season to season and site to site. In recent years,
outlook crests have been above the observed crest about as often as
they have been below the observed crest. The uncertainty of
forecasts tend to be less than the uncertainty of outlooks due to
their shorter lead time.
Users of these products are encouraged to contact their nearest
National Weather Service forecast office for continued updates of
meteorological conditions, which can have significant impacts on
flood planning and flood fighting activities.
Outlook numbers for locations not represented in AHPS products are
not being issued with this text product. For additional quantitative
information, please refer to AHPS products for probabilistic
forecasts of potential flooding. Refer to flood forecasts, if any
are currently issued, for information about ongoing or anticipated
This is the last scheduled spring outlook of the season. If
significant changes occur subsequent to this product, additional
outlooks can be released to address needs.
Additional river information can be found in the daily hydrologic
activities discussion, flood forecasts for rivers near or above
flood stage, daily river forecasts, AHPS products, and the monthly
water supply outlook, all issued by this office. Additional spring
outlook graphics can be accessed at the following url:
Current Snow Conditions
The conditions listed below are based on observations and model data as of Wednesday morning, March 1st.
Snow depths across the central and eastern plains of Montana are
generally less than 3 inches, with water equivalents less than half
Wyoming and Colorado Plains
A recent storm has dropped 6-12 inches of snow across the plains
of Wyoming, with water equivalents in the 1-2 inch range. There is
very little snow being reported in the Colorado plains.
Snowpack conditions in the mountainous areas of the basin vary
from one watershed to another. In Montana, the Jefferson,
Musselshell, Missouri headwaters, Sun, Teton, Marais, St. Mary,
and Milk River Basins are reporting a near to slightly below
normal snowpack (80-100%). In Wyoming, the Tongue, Bighorn, Powder, and lower Yellowstone River Basins are reporting a near to slightly above normal snowpack (90-110%), with the Wind River (180%), and North Platte (110-130%) river basins reporting an above average snowpack. In Colorado, the higher elevations of the South Platte are reporting an above average snowpack (120-140%).
Significant melting has occurred across North Dakota over the past two weeks. Portions of central North Dakota are reporting 6-12 inches of snowpack, with water equvalents in the 1-3 inch range. Elsewhere across the state, snow depths are generally less than 6 inches, with water equivalents less than 1 inch.
The warm weather over the past couple of weeks has also melted much of the snow in South Dakota. The Black Hills are reporting 6-12 inches of snow depth, with water equivalents in the 1-2 inch range. Elsewhere across South Dakota, snow depths are generally less than 4 inches, with water equivalents less than half an inch.
Snow depth across northwestern Iowa and far southwestern Minnesota is generally less than 3 inches, with water equivalents less than half an inch.
A storm late last week dropped snow across the northern portion of
Nebraska. 3-8 inches of snow remain on the ground as of this morning, with water equivalents generally less than 1.50 inches. The warm weather over the next week should melt much of this remaining snow. Little or no snow is being reported across the remainder of the state.
Missouri and Kansas
There is no snow being reported in these two states.
Current Soil Moisture Conditions
Across Montana, North Dakota, and north-central Wyoming, autumn rains and high amounts of winter precipitation have provided sufficient moisture to the region. Generally speaking, the shallow surface soils in these areas are wetter than normal. Elsewhere, the US Drought Monitor indicates moderate drought across eastern Colorado, western Kansas, northeastern Wyoming, western South Dakota, and central Missouri. Abnormally dry conditions are indicated across eastern Kansas and southwestern Nebraska. The remainder of the basin has near normal soil conditions. Isolated frost depth reports suggest that soils in the northern half of the basin have frost penetration ranging from 1-2 feet. Locations in the basin's southern states are reporting frost depths of less than a half of a foot.
Current River Conditions
Many of the rivers in the northern portion of the basin are still
ice-affected. Generally, river levels in this portion of the basin
are currently running normal to slightly above normal, or estimated to
be so if the rivers are frozen. In the southern part of the basin, rivers
across Missouri and Kansas currently have flow conditions that are
near to slightly below historical medians. River levels across Colorado, Nebraska, and Iowa are currently running near to above average.
A SUMMARY OF RIVER FLOW CONDITIONS AT SELECTED RIVER STATIONS FOR
MARCH 1ST FOLLOWS:
||LONG TERM MEAN(CFS)
|BIG SIOUX RIVER
||ST. JOSEPH, MO