Extended Streamflow Guidance
Issued by NWS Missouri Basin, Pleasant Hill

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FGUS63 KKRF 281800

                       SPRING FLOOD OUTLOOK
                      NATIONAL WEATHER SERVICE
                         PLEASANT HILL, MO
                            FEB 28, 2018



This Outlook is not for public release until Wednesday, February 28,

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.


Flood risk this Spring across the Missouri River basin varies.  In
the northern portion of the mountainous west, and in the plains of
Montana, there exists an enhanced risk for flooding as compared to
historical normal.  Across the Dakotas, and in the eastern third of
the Missouri River basin, a reduced risk for flooding, as compared
to historical normal, exists.  Elsewhere, flood risk is near 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 location can have a
reduced risk for flooding as compared to normal, yet still be
expected to experience flooding this season.  Finally, a location can
have an enhanced risk for flooding, as compared to normal, and yet
still not be predicted to flood this year.

Snowpack in the St. Mary and Milk River basins, the Upper Missouri
River basin above Ft. Peck, and the Yellowstone River basin, is well
above normal.  Headwaters of the North Platte and South Platte Rivers
have slightly below, to well below normal snowpacks, respectively.
Some minor flooding in the northern mountainous west is likely this
year due to mountain snowmelt and expected Spring precipitation.
This flooding would be exacerbated if accompanied by ice jamming.
Minor flooding is projected along the Clarks Fork Yellowstone, Sun,
and Boulder Rivers in Montana this season.  Minor flooding is also
expected to occur along Clear Creek, and is possible along the Little
Bighorn River,  both located in Montana.  The Wind River in Wyoming
could possibly see minor flooding as well.

Plains snowpack is widespread, but generally shallow.  The primary
exception to this rule being the significant amount of plains
snowpack existing in eastern Montana. The extent and severity of
flooding from the plains melt will be dependent upon the rate of
warming, diurnal temperature fluctuations, the occurance of any rain
events while snow remains, and river ice action.  Conditions in
eastern Montana bears watching during the course of the next
few weeks.

Soils remain frozen over the northern plains. However, given the dry
Fall and early Winter, it is likely the soil, while frozen, remains
permeable to snow melt and Springtime rains.  Therefore, the frozen
ground conditions currently existing across the northern plains are
not expected to exacerbate runoff production.

According to the latest Drought Monitor, 60% percent of the Missouri
River basin is abnormally dry, or worse.  Thirty percent of the
basin is classified as being in drought.  However, even with these
dry conditions, flooding is projected to occur this season,
especially in the eastern and southeastern portions of the basin.

Minor flooding is expected in the Little Sioux River basin in Iowa.

Minor flooding is expected within the Marais des Cygnes River basin
in Kansas, and in the southern portion of the Big Blue River basin
in Kansas.  Moderate flooding is projected for Stranger Creek, and
within the Osage River basin in Kansas.

Minor flooding is likely along the Platte and Chariton Rivers in
Missouri, and along the Missouri River itself downstream of Nebraska
City. Moderate level flooding is projected to occur within the Grand
and Osage River basins in Missouri this season, as well as along the
Tarkio River.  Several of the smaller streams in south-central
Missouri experienced minor-to-moderate level flooding over the past
two weeks due to two rounds of rain.  Moderate level flooding will
occur episodically along the smaller tributaries to the Missouri
River in the State of Missouri during the next few months. This
is not atypcial, even given the abnormally dry Fall and Winter.

Freeze-up ice jam flooding has already been reported at many
locations this winter.  However impacts have been relatively minor
and localized in extent.  High water due to ice formation has been
reported along reaches of the Wind River in Wyoming, the North Platte
and South Platte Rivers in Nebraska, the Niobrara River in Nebraska,
and the Gallatin and Missouri Rivers in Montana.  Break-up ice jam
flooding is expected to be somewhat widespread this season, but
projecting locations and severity is difficult at best.

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 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:

   Current Snow Conditions

The conditions listed below are based on observations and model
data as of Wednesday morning, February 28th.

Montana Plains

Snow depths across the central and southeastern plains of Montana
are in the 15-25 inch range, with maximum water equivalents ranging
from 2-4 inches.  Across the northeastern plains of Montana,
snow depths are generally less than 10 inches with water
equivalents of less than 2 inches.

Wyoming and Colorado Plains

There is very little snow being reported in the plains of Wyoming
and Colorado.  Snow depths are less than 6 inches with water
equivalents less than one inch.

Mountainous West

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 an above normal snowpack (130-160%).  In Wyoming,
the Tongue, Bighorn, Powder, Wind, and Yellowstone River basins are
also reporting an above normal snowpack (120-170%).  The higher
elevations of the North Platte River basin are reporting a near to
slightly below average snowpack (80-110%).  In Colorado, the higher
elevations of the South Platte River basin are reporting a below
average snowpack (60-90%).

North Dakota

North Dakota has snow depths ranging from 5-10 inches with water
equivalents generally less than 2 inches.

South Dakota

South Dakota has snow depths ranging from 5-15 inches with water
equivalents generally less than than 2 inches.  The Black Hills are
reporting 15-25 inches of snow depth with water equivalents in
the 3-5 inch range.


Snow depths in the 5-10 inch range are being reported across far
northwestern Iowa with water equivalents less than 2 inches.  Little
or no snow is being reported across the southwestern portion
of the state.


There is very little snow being reported across Nebraska.  Snow depth
amounts are less than 3 inches with less than half an inch of water

Missouri and Kansas

No snow is being reported across Missouri and Kansas.

   Current Soil Moisture Conditions

A large portion of the Missouri River basin is experiencing drought
conditions.  The US Drought Monitor (last issued February 22nd)
indicates moderate to severe drought conditions across much of
the western Dakotas, eastern Montana, southern Colorado, southern
Kansas, and eastern Missouri.  Abnormally dry conditions are
indicated across the eastern Dakotas, southern Nebraska, northern
Kansas, western Missouri, and southern Iowa.  The remainder of the
basin has near normal soil conditions.  Isolated frost depth reports
suggest that soils across Montana, Wyoming, and North Dakota have
frost penetration ranging from 2-5 feet.  Frost depth reports across
South Dakota, Nebraska, and Iowa range from 1-2 feet.  Frost depths
of less than half a foot are being reported across Colorado, Kansas,
and Missouri.

    Current River Conditions

The majority of the rivers in the northern two-thirds of the basin are
iced over.  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.  Due to recent heavy rain, rivers across southern
Missouri are currently running above normal.  Rivers across Colorado,
Kansas, and northern Missouri have flow conditions that are near to
below historical medians.

A summary of river flow conditions at selected river stations for
February 28th follows:

                                    Long Term     Current
                                    Mean (CFS)      (CFS)
James River       - Huron, SD           99            54 (EST)
Big Sioux River   - Akron, IA          470           660 (EST)
Platte River      - Louisville, NE    7600          7550 (EST)
Kansas River      - Desoto, KS        2980          3380
Gasconade River   - Jerome, MO        2260          9920
Missouri River    - Omaha, NE        18800         26700
Missouri River    - Rulo, NE         30200         36200
Missouri River    - St. Joseph, MO   35300         34800
Missouri River    - Waverly, MO      41200         38300
Missouri River    - Hermann, MO      66400        115000



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