Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 150446

Area Forecast Discussion
National Weather Service Sioux Falls SD
1046 PM CST Wed Feb 14 2018

.SHORT TERM...(This evening through Thursday)
Issued at 238 PM CST Wed Feb 14 2018

Fairly mild pleasant evening tonight with light winds and mostly
clear skies.  Could see some high clouds build north south of I-90.
These high cloud could limit the potential for fog.  RAP suggests
the potential fog patchy fog in low lying areas, while the HRRR has
backed off on the idea all-together.  Have a mention of fog in the
current forecast, but is fairly localized across far southeast SD
into northwest Iowa.

Cold front works south across the area on Thursday. Cold air lags
behind the front, but once the cold air advection develops in the
low levels, winds should increase driving wind chills into the
single digits and teens. Could also see some light snow develop
mainly along and north of I-90. Not a lot of lift but a fairly deep
dendritic layer in the near surface layer develops as temps tumble.
Snow amounts should be fairly light, generally 1/2 an inch or less.
Heaviest accumulations are expect across central South Dakota, where
slightly better dynamics exist.

.LONG TERM...(Thursday night through Wednesday)
Issued at 238 PM CST Wed Feb 14 2018

The extended starts off and ends cold, with a brief warm up in
between.  Thursday night, temperatures will fall to near zero, and
with relatively brisk north winds through the night, could see wind
chill values of -10 to -20 below.  Developing southwesterly flow
aloft throughout the day on Friday will help draw warmer air into
the region. The mild temperatures last through Sunday, when a strong
cold front associated with a low pressure system moves along the
northern edge of the US.  Have raised winds closer to CONSMOS Sunday
into Monday. Behind the front, several mid level waves move through
associated with a large upper trough creating periodic chances of
precipitation from Sunday night through at least the first half of
next week. Details of the various waves are still model specific, so
left pops broad brushed for now. Behind this system, below normal
temperatures look to reign with 925 hpa temps remaining in the teens
below 0C.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1042 PM CST Wed Feb 14 2018

Models continue to back off of the fog potential tonight, so
removed fog from the TAFs other than a brief period at KSUX.
Otherwise, a frontal boundary will push through the area on
Thursday, bringing some light snow to areas mainly north of
Interstate 90, with the greater impact expected at KHON in the
afternoon. Along with that, will see MVFR/IFR ceilings with this
front. Behind the boundary, northerly winds will increase on
Thursday afternoon, gusting 25 to 30 kts into the evening.




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