756 
FXUS63 KFSD 302250
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
450 PM CST Sat Dec 30 2017

.SHORT TERM...(This evening through Sunday)
Issued at 449 PM CST Sat Dec 30 2017

Quite simply cold. The main story continues to be the excessive cold 
weather, with dry weather expected Sunday and beyond.

In the near term however, light snow is expected to spread across 
the region this evening into the early morning hours. The light snow 
band will be focused along a mid level boundary set up near the 
Missouri Valley along with the arrival of a shortwave. Moisture and 
the progressive nature of this wave remains a somewhat limiting 
factor to snowfall amounts, however with low and mid level 
temperatures squarely in the dendritic growth zone, expect very high 
snowfall ratios on the order of 20+:1. Expect a quick 1 to 3 inches 
of snowfall along and south of a Huron to Sioux Falls to Spencer IA 
line. Heaviest amouts will be across south central SD/near the 
Missouri River. Across the northeast North of this line, only a 
dusting to around a half inch can be expected. Light snow will 
quickly come to an end in the early morning hour in our east, and 
prior to midnight east of I-29. Winds will remain relatively light 
at less than 10 mph, so blowing snow should not be a concern, 
however reductions in visibility is likely in snowfall, as well as 
slick, snow covered roadways.

.LONG TERM...(Sunday night through Saturday)
Issued at 449 PM CST Sat Dec 30 2017

Temperatures will be extremely cold into New Year's Day with lows 
tonight from -15 to -22 and dropping even colder to -18 to -26 on 
Sunday night. Readings will be particularly cold for any New Year's 
Eve festivities. Skies will clear from north of south during the day 
Sunday, but with high reflectivity of snowpack and a 1050mb high 
building over the northern Plains, temperatures will struggle to 
even reach the single digits below zero. As a result, wind chills be 
be well into the chill warning criteria late tonight, and stick 
there into the morning of New Years Day. It is likely that readings 
will bump into the advisory category briefly during the day, but 
given the short time frame of this "improvement", will keep things 
warning from midnight tonight through noon Monday for simplicity's 
sake. Dry weather is expected through this period.

Temperatures moderate a little on Tuesday, with highs reaching the
teens and lower 20s, however this warming trend will be
short-lived. Another cold front drops across the northern Plains
on Tuesday night, but is expected to be a dry passage, with
moisture cut off from the region. Highs remain above zero
Wednesday into Friday, but generally in the single digits or
teens, while lows remain below zero.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1200 PM CST Sat Dec 30 2017

Snow will begin this evening for much of the area. During a 2 to 3
hour window, visibilities and ceilings will likely fall to IFR or
LIFR conditions, with only light snow and MVFR conditions on 
either side of that window. Timing will vary based on location, 
starting in the west and moving east through the evening. Snow 
will exit the region by 31/0900z. Only light accumulations are
expected. Light north winds with cold conditions continue through
Sunday.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Wind Chill Warning from midnight tonight to noon CST Monday for 
     SDZ038>040-050-052>071.

     Wind Chill Advisory until midnight CST tonight for SDZ038>040-
     050-052>071.

MN...Wind Chill Warning from midnight tonight to noon CST Monday for 
     MNZ071-072-080-081-089-090-097-098.

     Wind Chill Advisory until midnight CST tonight for MNZ071-072-
     080-081-089-090-097-098.

IA...Wind Chill Warning from midnight tonight to noon CST Monday for 
     IAZ001>003-012>014-020>022-031-032.

     Wind Chill Advisory until midnight CST tonight for IAZ001>003-
     012>014-020>022-031-032.

NE...Wind Chill Warning from midnight tonight to noon CST Monday for 
     NEZ013-014.

     Wind Chill Advisory until midnight CST tonight for NEZ013-014.

&&

$$

SHORT TERM...
LONG TERM...
AVIATION...VandenBoogart