Hydrologic Outlook issued December 13 at 10:15AM CST by NWS Bismarck ND

ESFBIS

Ice continues to form and move through the Bismarck and Mandan
stretch of the Missouri River. As of late Thursday afternoon, ice
continued to move all the way down to the Hazelton boat ramp area.
While this suggests lots of storage remains for the ice pans,
sooner…rather than later, ice will start to accumulate where the
river meanders down by the University of Mary. Once ice occupies a
continuous stretch across the Missouri River in that area, it
usually only takes about one day to fill the river channel up
through the Bismarck and Mandan area.

While it is impossible to predict exactly when the river through the
metro area will fill with ice, the effects of this freezing in of
the river are fairly well known.

Since 2010, once the river ice collects in the Bismarck and Mandan
area, the rise in the Missouri River ranges between 4.9 and 6.9
feet, with an average rise of just over 6.0 feet. The Bismarck gage
for the Missouri River is currently right around 4.7 feet. This
suggests if the river were to become ice filled or covered, the
Bismarck gage would rise to a maximum stage between 9.6 and 11.6
feet. Minor Flood Stage, where problematic high water begins, is
defined as a stage of 14.5 feet as measured at the Bismarck gage.

Once the river starts to collect ice, the river can rise very fast
and reach its winter maximum in less than 24 hours.

Slightly warmer weather over the second full weekend of December is
not going to cease ice production. Instead, falling snow beginning
Sunday evening and into early next week will encourage more ice
development. The icing in of the river is likely to occur within the
coming week, if not before.

As a reminder, people should avoid walking on the Missouri River as
ice accumulates. The first ice on the Missouri River tends to be a
collection of small, unstable ice pans that can give way with no
notice. Also, anyone who notices damaging high water should report
their observations to local emergency management.