From the National Weather Service in Sioux Falls:

...BLIZZARD WATCH IN EFFECT FROM SUNDAY MORNING THROUGH LATE
SUNDAY NIGHT...

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A BLIZZARD
WATCH...WHICH IS IN EFFECT FROM SUNDAY MORNING THROUGH LATE
SUNDAY NIGHT.

* TIMING...RAIN WILL MOVE INTO THE AREA SATURDAY NIGHT. THE RAIN
IS EXPECTED TO MIX WITH AND THEN CHANGE TO SNOW SUNDAY MORNING.
PERIODS OF HEAVY SNOW ARE POSSIBLE SUNDAY AFTERNOON AND SUNDAY
EVENING WITH SNOW DIMINISHING SUNDAY NIGHT. STRONG NORTH WINDS
LATE SUNDAY AFTERNOON AND SUNDAY NIGHT MAY PRODUCE WIDESPREAD
BLIZZARD CONDITIONS.

* ACCUMULATIONS...SNOWFALL AMOUNTS WILL RANGE FROM AROUND 5 INCHES
NEAR SIOUX FALLS AND WINDOM TO 10 INCHES AROUND MITCHELL AND
MARSHALL.

* WIND AND VISIBILITY...EAST WINDS OF 10 TO 20 MPH SUNDAY MORNING
WILL SHIFT TO NORTH AT 25 TO 40 MPH SUNDAY AFTERNOON AND SUNDAY
EVENING. THE COMBINATION OF SNOW AND WIND WILL CREATE THE
POTENTIAL FOR BLIZZARD CONDITIONS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A BLIZZARD WATCH MEANS THERE IS A POTENTIAL FOR FALLING AND/OR
BLOWING SNOW WITH STRONG WINDS AND EXTREMELY POOR VISIBILITIES.
THIS CAN LEAD TO WHITEOUT CONDITIONS AND MAKE TRAVEL VERY
DANGEROUS.