SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE
MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL, MO
MARCH 08, 2023
NARRATIVE PART 1 OF 1
ATTN WFO'S SERVED BY MBRFC.
This Spring Flood Outlook is not for public release until Thursday,
09 March 2023.
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 within the Missouri River basin varies, with
much of the basin having a reduced flood risk due to the ongoing
drought. However, as a result of a near-to-above average mountain
snowpack, and a significant plains snowpack, there also exists
pockets of the basin having a near normal to even enhanced flood
risk for Spring 2023.
To provide context, a normal risk indicates that a location that
typically experiences Spring time flooding is likely to see
flooding again this year. However, a normal risk for flooding does
not necessarily mean that a location is expected to flood. For those
locations which do not typically experience flooding, a normal risk
simply indicates that flooding is again not expected this year. By
the same token, a reduced risk of flooding does not necessarily
mean that flooding is not expected. On the other hand, an
enhanced risk does not necessarily indicate flooding is likely.
The Missouri River basin is in its third year of continuous
drought. The time period covered by Water Years 2020, 2021, and
2022, extending from October 2019 through September 2022, was the
10th driest 3-year period in 125 years of record keeping for the
basin. To provide context, the Dust Bowl years of the 1930s had
3-year stints that ranked as the 1st, 2nd, 4th, 5th, and 6th
driest 3-year periods on record. The latest Drought Monitor,
released 02 March 2023, categorizes 56 percent of the Missouri
River basin in drought.
Mountain snowpack overall is generally near average. The exception
being the North Platte River basin, where an above average snowpack
exists thus far this year. Minor flooding along the North Platte
River in Wyoming is anticipated.
Water supply forecasts issued in early February by the National
Weather Service project generally lower than average
April-September runoff volumes for the mountainous west. Again,
the one exception being the North Platte basin, which is expected
to produce an above average runoff volume in 2023. More
information regarding current Water Supply Forecasts can be
accessed at weather.gov/mbrfc/water
An appreciable plains snowpack exists over the Milk River basin,
across much of North Dakota and the eastern half of South Dakota,
and in extreme northwest Iowa. The plains snowpack, where it
exists, is thought to have precluded the development of a deeply
frozen ground condition. Where plains snowpack is absent, the
ground has either now thawed, or if frost still exists, is thought
to remain fairly porous due to the ongoing drought conditions.
In other words, while the ground may still be cold, the general
absence of soil moisture to lock into place should allow for some
infiltration of future rain events and/or snowmelt. Therefore,
frozen ground is not expected to exacerbate flood risk for the
Missouri River basin this Spring.
Despite below normal streamflows this Fall and Winter, river ice
action has already presented some challenges within the Missouri
River basin this winter. River ice has resulted in elevated
river stages along the Gallatin River in Montana, the South
Fork Shoshone River in Wyoming, and along the lower reach of the
North Platte River in Nebraska. Thus far, impacts from these
western area freeze-up ice jams have been minor and localized.
The bitter cold snap which draped the basin in mid-to-late
December also resulted in ice jams along the lower Missouri River,
one jam in the Nebraska-Iowa reach of the river, and a separate
one in the reach downstream of Kansas City. Neither jam resulted
in flooding, but both jams resulted in record low stages in the
stretches of the river below each of the respective jams. Going
forward, it is thought that the Missouri River basin has a low
risk for ice jam break-up flooding this season. However, as long
as there is ice in the rivers, and a snowpack on the ground, the
risk is nevertheless present. Please note, the probabilistic
quantifications that form the basis for this Spring Flood Outlook
do not take into account the presence of river ice.
Springtime flooding in the lower one-third of the basin, including
southern Iowa, eastern Kansas, and the state of Missouri, is driven
by typical thunderstorm activity. Minor flooding has already
occurred along some of the tributaries in the state of Missouri
this calendar year, and episodic flooding is likely to continue
through this Spring in this region of the basin.
The following state by state flood potential discussions are based
on long-range probabilistic river outlooks developed this week.
Again, it must be stressed, these outlooks do not take into account
the presence of river ice.
In Wyoming, minor flooding is likely along the North Platte River.
In North Dakota, minor flooding is expected along the Cannonball
River and along Apple Creek. The James River and Beaver Creek
are also being watched closely.
In South Dakota, moderate flooding is expected along the James
River and in the upper reach of the Big Sioux River. Snake Creek
may also experience moderate level flooding. Minor flooding is
likely along the Vermillion and White Rivers, and Turtle Creek is
also projected to have minor flooding.
In Iowa, minor flooding is likely along the Nishnabotna River,
along the upper reach of the Little Sioux River, and on the lower
end of the Big Sioux River. .
In Kansas, Stranger Creek will experience moderate level flooding,
while the Marais des Cygnes and Little Osage Rivers are likely to
have minor flooding.
In the state of Missouri, moderate flooding is likely along the
Grand, Crooked, Blackwater, Moreau, South Grand, and Tarkio
Rivers. Moderate level flooding is also expected along Wakenda
and Big Creeks. Minor flooding is projected for the Chariton,
Lamine, Big Piney, Gasconade, Little Osage, Marmaton, Sac, and
Platte Rivers. Minor flooding is also expected along Moniteau.
Roubidoux, and Petite Saline Creeks.
The Missouri River from Nebraska City to the mouth could also
see episodic minor flooding this Spring.
These projections of river stages 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 location to location. The uncertainty of
forecasts tend 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 preparedness planning and flood fighting activities.
For additional quantitative information please refer to AHPS products
for probabilistic outlooks of potential flooding. Refer to short-term
flood forecasts and products, if any are currently issued, for
information about ongoing or near-term anticipated flooding.
This is the last scheduled Spring Outlook of the season. Should
significant changes occur subsequent to this Outlook, additional
Outlooks can be released to update expected conditions.
Additional river information, including the monthly Water Supply
Outlook, can be accessed at the following URL:
http://weather.gov/mbrfc
Current Snow Conditions
The conditions listed below are based on observations and model
data as of Wednesday morning, March 8th.
Montana Plains
Snow depths of 3 to 11 inches are being reported across the plains
of the Milk basin in northern Montana with water equivalents
in the 2.0-4.5 inch range. Elsewhere across eastern Montana,
snow depths are generally less than 3 inches with water
equivalents less than 1.0 inch.
Wyoming and Colorado Plains
Snow depths of generally less than 3 inches are being reported
across the plains of Wyoming and Colorado with water equivalents
less than 0.5 inches.
Mountainous West
Snowpack conditions in the mountainous areas of the basin are
generally near normal. In Montana, the Jefferson,
Musselshell, Missouri headwaters, Sun, Teton, and Marais River
basins are reporting a near normal snowpack (90-110%).
The St. Mary and Milk basins are reporting a near normal
snowpack (88%). In Wyoming, the Tongue, Bighorn, Powder,
Wind, and Yellowstone River basins are reporting a near to
above normal snowpack (100-115%). The higher elevations of
the North Platte River basin are reporting an above normal
snowpack (125%). In Colorado, the higher elevations of the
South Platte River basin are reporting a near normal
snowpack (103%).
North Dakota
Snow depths of 15 to 20 inches are being reported across much
of North Dakota with water equivalents in the 2.0-7.0 inch range.
Lower snow depths of generally less than 6 inches are being
reported across extreme western North Dakota with water equivalents
less than 2.0 inches.
South Dakota
The Black Hills in South Dakota have 10 to 36 inches of snow depth
with water equivalents in the 3.0-9.0 inch range. Snow depths
of 8 to 24 inches with water equivalents generally in the
2.0-5.0 inch range are being reported across the eastern half
of the state. Lower snow depths of generally less than 6 inches
are being reported across the western half of South Dakota with
water equivalents generally less than 2.0 inches.
Iowa
Snow depths of 5 to 15 inches are being reported across the
northwestern corner of Iowa with water equivalents in the
2.0-4.0 inch range. Little to no snow is being reported
across southwestern Iowa.
Nebraska
Snow depths of 1 to 5 inches are being reported across extreme
northern Nebraska with water equivalents generally less than 1.0 inch.
Elsewhere across the state, little to no snow is being reported.
Kansas
No snow is being reported across Kansas.
Missouri
No snow is being reported across Missouri.
Current Soil Moisture Conditions
The US Drought Monitor indicates that much of the Missouri
River basin is experiencing below normal soil moisture
conditions. Extreme to exceptional drought is indicated across
much of Nebraska and the western half of Kansas. Severe to extreme
drought is indicated across northern Montana, eastern Wyoming,
eastern Colorado, and northwestern Iowa. Abnormally dry to moderate
drought is indicated across much of the remainder of the Missouri
River basin. The exception is across northeastern Kansas
and most of Missouri where normal to above normal soil moisture
is indicated.
Isolated frost depth reports suggest that soils across Montana,
Wyoming, South Dakota, and North Dakota have frost penetration
ranging from 0.5 to 3 feet. Frost depths of less than 0.5 feet
are being reported across Nebraska, Iowa, Colorado, Kansas, and
Missouri.
Current River Conditions
A large majority of rivers across the northern half of the
Missouri River basin are iced over. Generally, river levels
across the basin are currently running near to below normal, or
estimated to be so if the rivers are frozen. Rivers across
southern Missouri are running above normal due to recent rainfall.
A summary of river flow conditions at selected river stations for
March 8th follows:
Long Term Current
Mean (CFS) (CFS)
James River - Huron, SD 204 67 (EST)
Big Sioux River - Akron, IA 825 800 (EST)
Platte River - Louisville, NE 8140 8500
Kansas River - Desoto, KS 3460 3120
Gasconade River - Jerome, MO 2360 7310
Missouri River - Omaha, NE 17900 19600
Missouri River - Rulo, NE 29800 31500
Missouri River - St. Joseph, MO 36100 30200
Missouri River - Waverly, MO 42300 38000
Missouri River - Hermann, MO 68900 97200
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