Hydrometeorological Discussion
Issued by NWS North Central River Forecast Center

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Hydrometeorological Forecast Discussion
NWS North Central River Forecast Center Twin Cities/Chanhassen MN
1134 AM CST Thu Dec 8 2016

...Precipitation...

The region continues to be under the influence of the large storm
system over southeast Canada, with northerly winds continuing to
usher cold air into the area. Widespread light snow and flurries
were seen from the Dakotas, all the way across Minnesota and Iowa
and into the Great Lakes. The cold air also caused significant
lake effect snow with some of the typical favored areas seeing
amounts from 3 to 6 inches. Parts of the U.P. of Michigan saw
8 to 10 inches. Water equivalent was only a few hundredths at most
for the majority of the region, but water in the lake effect area
was between a third and two-thirds of an inch.

With a continued northwest flow of cold air into the region,
expect light snow with localized lake effect activity to continue
through Friday and into Saturday. Then another weather disturbance
looks to bring significant snow in a band from South Dakota
across southern Minnesota and northern Iowa later Saturday, and
extending from Wisconsin and Illinois into Michigan and Indiana by
Sunday. Snow amounts in this area could be in the 3 to 6 inch
range, perhaps higher in some places, with water equivalents of up
to about a half inch.

...Hydrologic Conditions...

Rain and melt from before the recent cold spell caused rivers to
rise across much of the region.  In Minnesota, slow responding
rivers have finally crested, including the Crow River - above
bankfull stage at Delano - and the Mississippi River, which is
causing bankfull conditions on the St. Croix at Stillwater.  The
Mississippi is essentially at a local crest for all locations
between Dam 3 in Red Wing and Dam 17 at New Boston/Keithsburg.

The rise on the upper Mississippi will continue to travel
downstream toward St. Louis in the next several days, with St.
Louis expected to crest early on Monday.  While no flooding is
expected on the major rivers, flows are well above normal for
this time of year.  The system is vulnerable to future runoff,
and, importantly with the cold air setting in, the region is
going into the freeze-up with high flows and wet soils, which
could contribute to high spring melt runoff.  The USGS lists
streamflows in the 90th and above percentiles for nearly all
tributaries north of a line from Des Moines to Quad Cities to
Milwaukee.  The Mississippi is above the 75th percentile all the
way to the confluence with the Ohio.

With very cold air finally moving in over the region, there will
be an increased potential for freeze-up ice jams in the next
several days and weeks.  Several rivers are already showing ice
affects at their gages, with either erratic readings or
indications of an ice bite reduction in flow/stage, or the
beginnings of an ice jam.  People with assets on or near rivers
that are prone to ice jamming should be aware and prepared.  Ice
jam flooding can happen fast with very little warning.

For additional and more in-depth information concerning river
forecasts, precipitation and all hydrometeorological information
in the NCRFC area of responsibility, please refer to the NCRFC
web page at:     http://www.weather.gov/ncrfc

Emergency Call Back List:  JDT...BAC...RJW

If no response from this list, call the DOH, SCH or HIC.


$$

...MAW/JMP...





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