SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE
MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL, MO
MARCH 11, 2020
NARRATIVE PART 1 OF 1
ATTN WFO'S SERVED BY MBRFC.
This Spring Flood Outlook is not for public release until Thursday,
12 March 2020.
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 is above normal for much of the Missouri River
basin this year. The largest departure from normal flood risk exists
in the northern and eastern portions of the basin, where chances for
flooding range from 10 percent to as much as 50 percent greater than
normal.
A normal risk indicates that a location that typically experiences
Spring time flooding may flood again this year. A normal risk for
flooding does not necessarily mean that a location will flood,
however. 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. An
increased risk does not necessarily indicate flooding is likely.
Mountain snowpack overall is near to slightly above normal. However,
widespread, significant flooding in the mountainous west is not
likely due to mountain snowmelt alone. Water supply forecasts
issued in early March by the National Weather Service project
normal to slightly above normal April-September runoff volumes
for the mountainous west.
The only appreciable plains snowpack that still remains is located
in eastern North Dakota, where liquid equivalent amounts range from
1 to 3 inches. Plains snowmelt has already led to flooding within
the Milk River basin in Montana, the James River basin in South
Dakota, the Big Sioux River basin in South Dakota and Iowa, and
the Little Sioux River in Iowa.
A relatively mild winter has precluded significant frozen ground
development across most of the northern plains. Far northern areas
of the basin still retain frozen ground conditions, but overall
frozen ground will not play a factor in Spring 2020 runoff.
Mild temperatures have also mitigated the ice jam break-up flood
threat for the Missouri River basin. While river ice remains along
certain stream reaches in the northern and western portions of the
basin, the potential for ice jam breakup flooding has all but
passed.
2019 was the 3rd wettest year for the basin on record, outmatched
only by 1993 and 1915. As a result, the majority of the Missouri
River basin has wetter-than-normal soils.
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. Flooding has already occurred in
this area, and will continue off and on throughout the spring and
early summer.
The following state by state flood potential discussions are based
on long-range river outlooks developed this week.
Minor flooding is expected along the James River and Pipestem Creek
in North Dakota.
Minor flooding is projected to occur along the White River in South
Dakota, and has already occurred along the Vermillion River and
Firesteel Creek. Moderate level flooding is ongoing along the Big
Sioux River, and on Turtle Creek. The James River has now reentered
major flood category.
Minor flooding is expected along Lincoln, Turkey, and Shell Creeks
in Nebraska. Minor flooding is also projected along the Big Blue,
Little Blue, West Fork Big Blue, and Platte Rivers. Moderate level
flooding is likely for Wahoo Creek.
In Iowa, the Floyd, Rock, and Ocheyedan Rivers are likely to see
minor flooding. The Little Sioux River is currently in moderate
level flooding. The Big Sioux River is currently in minor level
flooding, and will likely experience moderate level flooding some
time this season.
Kansas streams likely to experience minor flooding this Spring
include the Little Blue, Big Blue, Marmaton, Black Vermillion,
Vermillion, Republican, Solomon, and Saline Rivers. Salt Creek is
also projected to experience minor flooding. The Little Osage,
Smoky Hill, and Marais des Cygnes Rivers are likely to see
moderate level flooding, as is Stranger Creek.
In the state of Missouri, the Little Osage, Marmaton, Crooked,
Blackwater, Moreau, and Sac Rivers have already experienced minor
flooding. Wakenda, Moniteau, Petite Saline and Big Creeks have as
well. The Chariton, Big Piney, Gasconade, Osage, and Maries Rivers,
and Roubidoux Creek, are all likely to experience minor flooding as
well this season. The Grand River has already seen moderate level
flooding. Crooked River, Blackwater, Lamine, Little Osage, Sac,
South Grand, Tarkio, and the Platte Rivers are all projected to
have moderate level flooding this season. Wakenda and Big Creeks
will also projected to see moderate level flooding this year.
The Missouri River itself extending from Nebraska City, Nebraska
to the mouth at St. Louis is likely to experience flooding this
year. Currently, the Missouri River at Gasonade, Missouri is
believed to be above flood stage. Flooding along the Missouri
River will generally be in the minor-to-moderate level category.
As we move later into the season, major level flooding downstream
of Kansas City cannot be ruled out. Many of the levees along the
Missouri River downstream of Gavins Point have yet to be fully
restored after the 2019 flood. Although the National Weather
Service is in continual communication with other federal agencies
with regard to current stage-flow relationships, river stage
outlooks and forecasts this year have a high degree of uncertainty
due to the current state of the channel and overbank areas.
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. If
significant changes occur subsequent to this Outlook, additional
Outlooks can be released to address needs.
Additional river information, including the monthly Water Supply
Outlook, can be accessed at the following URL:
http://weather.gov/mbrfc
Current Snow Conditions
Warm weather across the lower elevations of the Missouri River basin
has melted much of the snow over the past two weeks.
The conditions listed below are based on observations and model
data as of Wednesday morning, March 11th.
Montana, Wyoming, and Colorado Plains
Little or no snow is being reported across the plains of Montana,
Wyoming, and Colorado.
Mountainous West
Snowpack conditions in the mountainous areas of the basin are generally
near to above normal. In Montana, the Jefferson, Musselshell,
Missouri headwaters, Sun, Teton, and Marais River basins are
reporting a near to above normal snowpack (100-130%). The St. Mary and Milk
basins are reporting a normal to above normal snowpack (90-110%).
In Wyoming, the Tongue, Bighorn, Powder, Wind, and Yellowstone River
basins are reporting a near to above normal snowpack (90-130%). The higher
elevations of the North Platte River basin are reporting a near
to above normal snowpack (100-120%). In Colorado, the higher elevations of
the South Platte River basin are also reporting a near to above normal
snowpack (100-120%).
North Dakota
The eastern portion of North Dakota has snow depths in the
3-7 inch range with water equivalents in the 1-3 inch range.
The western portion of the state has little or no snow.
South Dakota
The Black Hills in South Dakota have 8-22 inches of snow depth
with water equivalents in the 3-6 inch range. Snow depths across the
remainder of South Dakota are generally less than 2 inches
with water equivalents less than half an inch.
Iowa
Snow depths less than 2 inches are being reported across extreme northwestern
Iowa with water equivalents less than half an inch. The rest of western
Iowa has little or no snow.
Nebraska, Kansas, and Missouri
There is little or no snow across Nebraska, Kansas, and Missouri.
Current Soil Moisture Conditions
The US Drought Monitor indicates that much of the Missouri River basin
is experiencing near to above soil conditions. Abnormally dry conditions
are indicated across eastern Colorado, northwestern Kansas, and extreme
southwestern Nebraska. Moderate drought is now being indicated across
northeastern Colorado.
Isolated frost depth reports suggest that soils across Montana, Wyoming,
South Dakota, and North Dakota have frost penetration ranging from 1-3 feet.
Frost depths of less than 1 foot are being reported across Nebraska, Iowa,
Colorado, Kansas, and Missouri.
Current River Conditions
The majority of the rivers in the northern one-third of the basin are
ice-affected. Generally, river levels in this portion of the basin are
currently running near to above normal, or estimated to be so if the
rivers are frozen. In the southern two-thirds of the basin, rivers are also
running near to above normal with the exception of eastern Colorado, western
Kansas, and extreme southwest Nebraska where flows are below historical
medians.
A summary of river flow conditions at selected river stations for
March 11th follows:
Long Term Current
Mean (CFS) (CFS)
James River - Huron, SD 173 7100 (EST)
Big Sioux River - Akron, IA 1150 8430 (EST)
Platte River - Louisville, NE 9790 16200
Kansas River - Desoto, KS 3420 18000
Gasconade River - Jerome, MO 2570 3080
Missouri River - Omaha, NE 30500 73000
Missouri River - Rulo, NE 30400 66700
Missouri River - St. Joseph, MO 37300 77400
Missouri River - Waverly, MO 44600 108000
Missouri River - Hermann, MO 75400 168000
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