Hydrometeorological Discussion
Issued by NWS North Central River Forecast Center

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AGUS73 KMSR 202021

Hydrometeorological Forecast Discussion
NWS North Central River Forecast Center Twin Cities/Chanhassen MN
321 PM CDT Thu Jul 20 2017

UPDATE: the NCRFC will be staffed overnight tonight in support of
ongoing moderate to major flooding and potential convective rains.


Strong thunderstorms with very heavy rainfall developed yesterday
afternoon across eastern North Dakota and southern Minnesota and
moved eastward last night through early this morning across
southern Wisconsin to northern Illinois.  The heaviest rain,
with amounts in the 4 to 7 inch range, fell in in southeast
Minnesota along the Mississippi River across southwest Wisconsin
into northern Illinois.  Numerous areas had 1 to 3 inches with
scattered thunderstorm from southwest Minnesota to northeast Iowa
and over southwest Wisconsin into northern Indiana.

In the forecast today... the area of thunderstorms and the heavier
rainfall will shift a bit south and eastward this morning.
Another inch of rain was forecast early this morning mainly in
northern Illinois to northern Indiana.  Scattered thunderstorms
with moderate rainfall amounts, around a quarter to half inch on
average, are expected in eastern North Dakota, across Iowa and
lower Michigan.

Then through tomorrow night another round of strong thunderstorms
with heavy rain will impact much of these areas again. Areas that
could see another 1 to 4 inches include southern Minnesota,
northern Iowa, southern Wisconsin, northern Illinois to northern

...Hydrologic Conditions...

The heavy rains from last night in southwestern Wisconsin caused
quick rises on the Trempealeau, La Crosse, Kickapoo and Baraboo
Rivers.  Moderate to major flooding is occurring or imminent on
those rivers.

Significant flooding continues in southeastern Wisconsin and
northeastern Illinois along the Fox and Des Plaines Rivers
after heavy to record rainfall last week. Moderate to major levels
continue at four forecast points.  These rivers got an additional
shot of rain early this morning which put the Des Plaines River at
Des Plaines back above moderate... is pushing Algonquin near
record, and caused slight re-rises across the region.

The rainfall expected in the next three days has a chance of
causing additional significant flooding.  The main threat is day 2
QPF centered over northern Illinois, which could push the Rock,
Fox, and Des Plaines Rivers into major flooding, including points
that have recently set new records as well as downstream
locations that didn`t make it to major with last week`s rain.
Additional locations outside of the listed rivers are also likely
to see rises of the bankfull to minor and near moderate variety.
This includes locations in southern Minnesota, Wisconsin, eastern
Iowa, most of Illinois, Indiana and southern Michigan.

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

UPDATE: the NCRFC will be staffed overnight tonight in support of
ongoing moderate to major flooding and potential convective rains.



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