National Weather Service Bismarck ND

Hydrologic Outlook for Snowmelt and Upcoming Weather

Another very strong precipitation event is scheduled to arrive in
North Dakota late Thursday and continue through much of the weekend.
Not unlike our most recent storm, this one is generally going to be
centered on south-central North Dakota with rainfall totals as high
as 3 inches possible. As of Wednesday, models suggest this storm
will likely impact every major watershed in North Dakota.

So for western and central North Dakota, here`s a rundown of
potential impacts based on the current expectations.

Over in the James River basin, rainfall totals between one and 2.5
inches of rain are possible. This rain is most likely to fall on
soils that are still permeable, but fairly wet. This would suggest
runoff will begin once somewhere around one-half inch of rain is
received. Rainfall rates will be extremely important in this area as
some of the precipitation received could be the result of
thunderstorms, which locally can induce much higher rainfall rates, which in turn leads to much higher rates of runoff.

In south-central North Dakota, streams east of the Missouri like
Beaver Creek near Linton and Apple Creek near Bismarck are also
under the threat of receiving higher rainfall rates and runoff due
to thunderstorms. These watersheds also contain fairly wet soils and
will see runoff quickly increase after roughly one-half inch of rain
is received.

In southwestern North Dakota, streams like the Cannonball, Cedar
Creek and the Heart River have a lower risk of strong thunderstorms,
but will also need to be watched due to potentially seeing some of
the overall highest rainfall totals. Farther north, the Knife River
still has a modest amount of snow, and that snow when combined with
a reasonable risk of around two inches of rain could create a
situation where substantial runoff will push the Knife River and
Spring Creek to new highs for the year.

Farther north, the Little Muddy near Williston and Long Creek in
Divide County have a fair amount of snow-water equivalent still on
the ground. Thus far the melt has been slow enough to where the vast
majority of the meltwater has been infiltrating into the ground.
This will continue to help alleviate some of the strongest drought
conditions seen in years across that area, but the risk of flooding
and strong runoff is certainly not zero even as this is the area
with the least risk of strong thunderstorms.

In north-central North Dakota, the Souris River basin still contains
what appears to be a widespread 2 or more inches of SWE. Thus far,
most of the meltwater from the snowpack has been infiltrating into
the ground. Where this has not necessarily been the case is in the
eastern portion of the basin where Willow Creek is nearing flood
stage for the second time this spring. Other places of concern under
the wrong melting conditions, are the Des Lacs River at Foxholm, and
the low-lying areas both upstream and downstream of Minot. Even as
this area is only expected to receive one to one and a half inches
of extra moisture. It is also in an area not favored to see
thunderstorms and their accompanying higher rainfall rates.
Nonetheless, it is probably the area with the highest chances of
seeing at least minor flooding going through the coming weekend.

The greatest certainty in all the above resides with the
continuation of wet soils for another week. While the risk of at
least minor flooding is growing all across western and central North
Dakota, at a minimum, this latest storm will keep the countryside
primed for producing runoff going forward for at least another week,
or more.

142 PM CDT Wed Apr 27 2022