Hoiatused, William L Guy Federal Building

Hydrologic Outlook issued December 11 at 3:42PM CST by NWS Bismarck ND ESFBIS The Missouri River now has ice pans floating downstream through the Bismarck and Mandan reach of the river. Thus far, the river continues to flow unimpeded with the ice most likely being carried down into Lake Oahe. While this often initiates the accumulation of immobile ice, and eventually higher water through the Bismarck and Mandan area, warmer weather later this week is likely to delay this annual ritual until sometime later in December. Nonetheless, residents and others interested in water levels through the metro area should remain vigilant for the eventuality of an ice covered Missouri River and higher water. 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. Again, warmer weather towards the end of the week is likely to minimize the chances of higher water this week, but with the winter season in full swing, the icing in of the river is likely to occur within the next few weeks. 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.