Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 151152

Area Forecast Discussion
National Weather Service Sioux Falls SD
552 AM CST Thu Feb 15 2018

.SHORT TERM...(Today and Tonight)
Issued at 307 AM CST Thu Feb 15 2018

Strong troughing across the western United States early this morning
with an increasing upper level jet from the southern into the
central Plains. As this jet increases and spreads east cold air will
drop south this morning and afternoon, bringing fairly strong
frontal forcing. The stronger frontal forcing appears to occur
during the afternoon and very early evening and the latest runs are
indicating some instability above the 750mb to 700mb boundary close
to highway 14. While the deeper dendritic layer does not match up
perfectly with the best forcing, there will be a couple hours when
things match up decently. Went ahead and increased pops and qpf for
this event with the highest amounts near highway 14. Will have the
chance for snow drop off quickly this evening but could see a tenth
of an inch or two across southwest MN from 0z to 3z.

Temperatures will start the day fairly mild in the 20s, rise a bit
through the morning then begin to drop during the afternoon. Wind
chill values will quickly drop below zero this evening and remain
below zero through Friday morning. Right now not looking like wind
chills will fall below 20 below so no advisories expected.

.LONG TERM...(Friday through Wednesday)
Issued at 307 AM CST Thu Feb 15 2018

Friday into Saturday should be fairly quiet. A weaker system will
move through on Saturday and could bring a quick shot of light
snow but at this time any accumulations would be minor. Cold high
pressure will drift southeast on Friday and bring a bit of a
breezy southerly wind Friday afternoon into the evening,
especially west of Interstate 29. This should allow for a little
warming, but only anticipating 30 to 35 in south central SD and
20s elsewhere as we will still be fighting off cold air from the
exiting high pressure as well as snow cover.

Friday night into Saturday winds will turn to the northwest but the
incoming air mass will be a bit on the mild side. With some enhanced
mixing highs should climb into the 30s, fighting through some
morning cloud cover as the weaker wave moves through.

By Sunday the pattern will begin to change and likely become more
active through early next week. Still too early to work out many
details. Overall we will likely see westerly flow over the northwest
United States gradually become troughier and turn winds to the
southwest across the Rockies. This will aide in creating a pattern
that allows the lower and mid level boundary to remain somewhat
locked in place as well as allow a series of upper level waves to
eject into the Central Plains. So, a very good chance for
precipitation, mainly in the form of snow, Sunday night into Tuesday
but amounts, duration and location are up in the air. While Sunday
will be mild, highs 35 to 45, colder air will drop south and highs
will be in the teens to lower 20s Monday and Tuesday.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 552 AM CST Thu Feb 15 2018

MVFR ceilings advancing into the KHON area within the first hour
of TAF behind cold front. Expect most ceilings will drop behind
this boundary into the MVFR range, with potential for brief IFR
ceilings and visibilities as snowfall develops later this morning
into early afternoon. The area of snow will diminish passing south
of the KFSD area late afternoon and early evening, leaving
conditions to be degraded primarily by the MVFR ceilings into
early evening toward KSUX. Drier air with advancing ridge of high
pressure will raise exiting ceilings as they evacuate later this
evening. Northerly surface winds will gust to 25 to 30 knots
during the late morning through evening hours.




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