Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 142305

Area Forecast Discussion
National Weather Service Sioux Falls SD
505 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 00Z TAFS through 00Z Thursday evening)
Issued at 459 PM CST Wed Feb 14 2018

Winds will drop off later this evening, and could see patchy fog
develop in lower lying areas. Will see an increase in high clouds
from the south later tonight which may limit additional fog
development. A frontal boundary will slide through the area on
Thursday, with winds transitioning to northerly and picking up
during the afternoon. May also see light snow develop behind the
boundary, with the potential for the greatest impact being at
KHON by 17Z.




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