...Spring Flood and Water Resources Outlook Update...
This Flood and Water Resources Outlook is for the James and Missouri
river basins of North Dakota, covering the period of 25 March
through 23 June, 2023. This outlook is an update to the Spring Flood
and Water Resources Outlook. 

Going forward, the National Weather Service will go back to the routine monthly issuance of the flood probabilities on, or near, the fourth Thursday of every month. The following message has four sections. The first provides some text on
the highlights of this outlook and conditions affecting the local
hydrology. The second section gives the current and historical risks
of flooding as determined by the Ensemble Streamflow Forecast model
of the National Weather Service. The third section gives the
current  probabilities for reaching flood stage at the listed
forecast locations. And finally, the fourth section covers the risk
of the river sites falling below the listed stages.

...Flood Outlook Highlights...
A persistent cold and wet pattern over the past couple of weeks has
continued to add Snow-Water Equivalent (SWE) across much of North
Dakota. Up to another inch of SWE has been added in a wide swath
from roughly Williston to Minot and down through the James River
Basin, with lesser amounts in the southwest quarter of the state.

The risk of flooding has changed somewhat for a number of locations.
In particular, the Knife River and Spring Creek basins are
considered slightly above normal due to an increase in SWE over the
past month. Others, such as Beaver and Apple creeks are somewhat
below normal due to the warm and dry soils even though they have
received fair amounts of SWE recently, but this has been somewhat
offset by earlier melting that had taken place.

Across the James River Basin, including Pipestem Creek, modeled
risks above Jamestown and Pingree and Grace City are below normal.
Again, this is due to the exceptionally warm and dry soils under the
snowpack. South of I-94, flood risk rises due to some of the highest
SWE content in the state.

The Little Missouri river is starting to show signs of runoff
arriving in North Dakota from the upper parts of its watershed, but
thus far runoff has been minimal.

In general, the dry and warm soils are still expected to
substantially reduce runoff from melting snow under all but the most
extreme of melt conditions, especially a rain on snow scenario. The
region remains in a persistent pattern of below normal temperatures
and all weather forecast models suggest this will continue into
April. However, the closer we get to April and beyond, the greater
the chance of seeing a rapid change in temperatures with daily highs
potentially well above freezing.

All that being said, one should remember that while the region is
nearing the end of the snow accumulation season, overall
precipitation trends upward as we go through March and into April.

These flood risks will be updated on, or about, April 27th as a part
of the routine release of the probabilistic Flood and Water
Resources Outlook.

...Missouri and Yellowstone Rivers...
Snowpack and SWE values remain near normal across the majority of
the Missouri and Yellowstone basins in Montana. However, due to last
year`s drought, runoff from the upper basins is expected to be
somewhat below normal due to the dry soils. Accordingly, flood risks
along the Missouri and Yellowstone Rivers above Lake Sakakawea
should be considered near normal. This would include the risk of
high water due to ice jams. In fact, the Yellowstone River is now
experiencing runoff in western Montana and ice is already starting
to move in the Billings to Miles City stretch of the river.

In the event of abnormally high spring runoff above Garrison Dam,
Lake Sakakawea is well below normal for this time of year and has
above normal storage available for any excess runoff. Below Garrison
Dam, runoff is not expected to be enough to create flood problems
due to high flow from the tributaries. However, there is always a
slight chance of high water in the event of a rapid melt resulting
in an ice jam if the tributaries were to discharge their ice ahead
of the Missouri River opening up through the Bismarck/Mandan area.
The Missouri River is now widely open from Garrison Dam on down
through about 8-10 miles south of Washburn. It will likely take at
least another week for the Missouri River near Bismarck to lose its

...Snowpack Conditions...
The snowpack has two distinct layers or components to it right now.
There is the snow/ice that was received early in the winter that
underwent some melting and consolidation during a warm period of
February. This part of the snowpack now more closely resembles
porous ice and is more resistant to melting than freshly received
snow. The remaining part of the snowpack is snow received largely
over the past several weeks. This relatively new and less
consolidated snow is now relatively easy to melt on sunny days even
with temperatures in the mid-20s.

Snowpack across the Missouri and James River basins remains thinnest
in the western quarter of the state, and increases as one looks
farther east. SWE content between one and slightly over two inches
is common, with locally higher amounts west of a line from Williston
on down through Dickinson and Lemmon, South Dakota. East of that
line, SWE rises rapidly as one gets towards the Missouri River with
SWE content between three and four inches being common, with locally
up to five inches. East of the Missouri River, SWE of around four
and a half inches is common from Garrison on down through Bismarck
and where the Missouri River enters South Dakota. Going farther east
into the Prairie Pothole Region and the James River Basin, five
inches of SWE is common, but there are fairly large areas with
between six and eight inches of water content in the snowpack.

...Current Drought Conditions...
The snowy winter has resulted in widespread improvements across
North Dakota with regard to drought designations. However, D0
(Unusually Dry) up through D1 (Moderate) drought remains in place.
The trend has been towards improvement and is likely to continue.

...Reservoirs and Natural Wetlands...
With only a few exceptions all man-made reservoirs, livestock dams,
and natural wetlands are at, or below, their normal water levels for
this time of year.

...Soil Conditions...
Soils across the basin are quite dry. Along with the soils being
dry, the insulating effect of the early snow has kept the soils
under the snow warmer than one would expect based on the winter
we`ve had this year. These warm and dry soils will allow
infiltration of rainfall and meltwater from the spring snowmelt
season under all but the most extreme of melt conditions.

...Weather Outlook...
In the 6-10 and 8-14 day outlooks, a cooler and wetter than normal
weather pattern is favored. Importantly though, cooler than normal
temperatures at this time of year includes weather patterns with
above freezing temperatures as the average daily high temperature in
the Bismarck area for April 1st is around 50 degrees. Looking at the
weeks 3-4 outlooks (1-14 April), the cooler than normal pattern
remains favored, while below normal precipitation is favored. When
looking at the one-month outlooks, the loss of La Nina seems to have
resulted in the equal chances designation for above normal, near
normal, or below normal temperature and precipitation for the
overall month of April. Lastly, the three-month outlooks for April,
May, and June combined  again favors a below normal temperature
outcome while retaining the equal chances designation for

...Ice Conditions...
All small lakes and wetlands are covered with ice of variable
thickness. Lakes with substantial snow cover are likely to have
thinner ice due to the insulating effect of the deeper snow.

In Table 1 below, the current (CS) and historical (HS) or normal
probabilities of exceeding minor...moderate...and major flood stage
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 greater 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.