Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 110916
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
316 AM CST Thu Jan 11 2018

.SHORT TERM...(Today and Tonight)
Issued at 315 AM CST Thu Jan 11 2018

Cold air pouring into the area along strong northwest winds gusting
to around 40 mph. Snowfall has been somewhat limited overnight, but
a couple of inches likely fell over parts of south central into east
central SD. This band of snow was progressing more quickly to the
east early this morning and a new band of snow was developing over
central and eastern Nebraska. This was in response to the southern
jet wrapping northward. Snowfall should consolidate across northwest
IA early this morning and continue through early afternoon before
drier air overwhelms any lift. The low levels will be within the
dendritic zone so patchy light snow and flurries will remain
possible, but the dry air should limit any potential. Did bring an
earlier end to the winter weather advisory for many locations and
don`t doubt that the advisories may be able to be canceled sooner.
While the wind and cold will still occur, snowfall of 1 to 2 inches
will likely not be enough to cause any reduced visibility once the
falling snow ends. Temperatures will be steady to falling through
the day with wind chill values about 10 to 20 below zero.

By tonight temperatures will fall and winds will still be about 10
to 15 mph. This will allow wind chill values to fall to to 20 to 30
below zero in many locations. Will likely issue a wind chill
advisory for locations along and north of a Chamberlain to Storm
Lake line for tonight and Friday morning once the current winter
weather advisories expire. Overnight lows will drop to about zero to
10 below. Temperatures could be colder, but for now expecting an
increase in cloud cover in central SD ahead of the next piece of
energy.

.LONG TERM...(Friday through Wednesday)
Issued at 315 AM CST Thu Jan 11 2018

Friday will see a more broad area of light snow as decent warm
air advection is expected within a nice dendritic profile. For now
the better chances appear to be along and south of a Huron to
Spencer IA line where 1 to 2 inches will be possible. Temperatures
will struggle into the single digits.

Friday night and Saturday will have continued cold conditions and
may need another wind chill advisory during this time. Lows should
be 5 below to 15 below zero with highs in the single digits.

Saturday night into Sunday will be a little less cold as an upper
level jet drifts east of the area before another wave drops south.
This will allow for some broad and unfocused warm air advection
which may bring a little light snow Sunday into Sunday night. Lows
about 5 above to 5 below with highs Sunday into the teens to mid 20s.

Cold air backs in Monday and Tuesday as the wave passes with lows
likely well below zero, especially Tuesday morning. Highs will be in
the single digits. Warmer air should arrive on Wednesday and all
indications are for a milder end to next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 553 PM CST Wed Jan 10 2018

An unpleasant next 18 to 24 hours for aviation concerns with
wintry system working through the area. Main precip band will
develop across central to northeast SD this evening, progressing
eastward overnight with secondary band developing across eastern
portions of northwest Iowa late tonight and Thursday morning.
Some lingering warm temperatures aloft could yield a brief period
of light freezing rain or sleet before precipitation changes to
snow. Main snow band should stay west of KFSD and KSUX, but will
will likely get a period of 1-2sm visibility due to just snowfall.
Winds will be but one other concern, shifting northerly behind
boundary this evening with frequent gusts of 30 to 40 knots into
Thursday. This will create areas of blowing snow once
accumulations develop and further act to reduce visibility.
Likely will have to drop visibilities down toward 1/4 to 1/2sm for
a short period once timing of more significant snowfall can be
determined.

Ceilings will drop to LIFR/IFR in snow band before drier air helps
to raise into MVFR range. Fair amount of MVFR ceilings likely to
persist well into Thursday.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until noon CST today for SDZ039-040-
     054>056-060>062-065>071.

     Winter Weather Advisory until 8 AM CST this morning for SDZ053-
     059-063-064.

MN...Winter Weather Advisory until noon CST today for MNZ071-072-080-
     081-089-090-097-098.

IA...Winter Weather Advisory until noon CST today for IAZ001.

     Winter Weather Advisory until 6 PM CST this evening for IAZ002-
     003-012>014-020>022-031-032.

NE...Winter Weather Advisory until noon CST today for NEZ013.

     Winter Weather Advisory until 6 PM CST this evening for NEZ014.

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...Chapman



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