Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 151741

Area Forecast Discussion
National Weather Service Sioux Falls SD
1141 AM CST Mon Jan 15 2018

.SHORT TERM...(Today and Tonight)
Issued at 446 AM CST Mon Jan 15 2018

Initial impressions are that conditions will not be quite as cold as
expected, but confidence and the difference are not enough to change
the current headlines. Wind chill values will still be in the 20
below to 40 below range, possibly just not below 35 below for
very long. An impressive, cold upper level low pressure dropping
south early this morning through MN was driving cold air in the
low levels southward. Broad cold air advection continues through
the morning which will keep breezy conditions in place with low
wind chills. Wind chill values will generally be from 25 below to
35 below across the area with a period this morning in southwest
MN where wind chill values may get as cold as 40 below. As
temperatures fall this evening and overnight wind chills will
again fall below 35 below at times over east central SD, southwest
MN and parts of northwest IA. Temperatures will warm little today
and still planning on highs from zero to 5 below in most

As for snowfall chances, by mid afternoon some weak warm advection
wraps around from the northeast and should provide a little focus
for some very light snow/flurries. At this time not expecting
anything more than a couple of tenths of an inch. The better chances
will be along and east of Interstate 29. Most of this activity will
end before midnight.

By tonight, clouds should begin to erode from west to east as cold
high pressure settles into central SD. Stronger winds of 10 to 20
mph are expected east of the James River through the night which
will keep the bitterly cold wind chills in place. Lows will likely
be 10 below to 15 below zero but could get close to 20 below near
Huron and possibly Chamberlain where winds have the best chance to
become light.

.LONG TERM...(Tuesday through Sunday)
Issued at 446 AM CST Mon Jan 15 2018

Wednesday through Friday will be back to much less cold
conditions, as well as no snow expected. In fact, temperatures
Thursday and Friday will climb above normal, mostly 30s on
Thursday and 40s on Friday. This is in response to upper level
ridging giving way to west to southwest flow aloft, bringing the
mild south and west flow in the low levels. Models still
indicating a wave developing just ahead of the main upper level
jet max, with the GFS the most aggressive while the ECMWF and
Canadian are much weaker and farther north. Nothing worth adding
any precipitation chances.

Saturday into Sunday continues to hold the next best chance for
precipitation. Obviously this far out there is not to much to get
excited about yet, but it does hold potential to be a longer
duration precipitation event than the past few we have had. Starting
out on the mild side there may be a little rain as well. But, a
lot of room for error and if the system comes out a little weaker
than forecast it would ride to the south, so at this time just
something to watch for.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1140 AM CST Mon Jan 15 2018

Main forecast concern are MVFR ceilings as well as visibility
reduction due to ice crystals and flurries. Much of the area is
reporting 1000-3000 ft ceilings this morning. With upper level
wave wrapping across Minnesota expect that continued MVFR ceilings
will continue through the afternoon along and west of I29 and
through the night east of I-29. With sunset expect that lower
ceilings will give way to a few mid clouds at FSD, HON and SUX as
drier air slowly is advected into the area and there is also a
loss of lift. Flurries and ice crystals will also continue to
lower visibilities below 6 SM at times through the afternoon.
Where lift and low clouds are more prevalent in sw MN this will be
predominant into the evening. Observations also show lower
visibilities across the James River Valley. As winds decrease and
any flurries end, visibilities should improve at KHON after
sunset. By 06Z VFR conditions expected at FSD, HON, and SUX
although winds of 10 to 20 kts expected to continue. Wind will
continue to decrease after sunrise Sunday as a surface high
pressure moves over.


SD...Wind Chill Advisory until noon CST Tuesday for SDZ038-050-

     Wind Chill Warning until noon CST Tuesday for SDZ039-040-056.

     Wind Chill Warning from 6 PM this evening to noon CST Tuesday
     for SDZ055-062.

     Wind Chill Advisory until 6 PM CST this evening for SDZ055-062.

MN...Wind Chill Warning until noon CST Tuesday for MNZ071-072-080-081-

     Wind Chill Warning from 6 PM this evening to noon CST Tuesday
     for MNZ098.

     Wind Chill Advisory until 6 PM CST this evening for MNZ098.

IA...Wind Chill Advisory until noon CST Tuesday for IAZ012-013-020-

     Wind Chill Warning until noon CST Tuesday for IAZ003-014-022.

     Wind Chill Warning from 6 PM this evening to noon CST Tuesday
     for IAZ001-002.

     Wind Chill Advisory until 6 PM CST this evening for IAZ001-002.

NE...Wind Chill Advisory until noon CST Tuesday for NEZ013-014.



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