Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 102312

Area Forecast Discussion
National Weather Service Sioux Falls SD
512 PM CST Mon Dec 10 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 259 PM CST Mon Dec 10 2018

While a west to southwest gradient will be in place through the day,
this gradient will slacken through the evening with light winds
expected overnight. A weak cool front will slide south and a
combination of light winds, a strong inversion, weak convergence
along the front and some near surface moisture could allow for some
patchy fog to develop. The better chances will be in far southeast
SD, northeast Nebraska, northwest IA and southwest MN late tonight
and early Tuesday morning. Lows will be on the chilly side from
about 12 to 18 degrees.

A trough of low pressure will move across the Northern Plains on
Tuesday and bring an increase in cloud cover, mainly mid and high
level clouds. Ahead of this wave winds will be fairly light and
highs should range from about 25 to 35 degrees. Some fairly strong
forcing will accompany the passage of the mid and upper level wave,
but moisture is so sparse that there should not be much more than
virga. There is a hint of some negative EPV, instability, above the
750 mb front so that might help get a little light snow going, and
will have some low pops in central SD towards northeast SD. If we
can get any light snow it would be late afternoon and early evening
from about Interstate 29 east.

.LONG TERM...(Tuesday night through Monday)
Issued at 259 PM CST Mon Dec 10 2018

Northwest winds will increase a bit on Tuesday night as the wave
passes but not expected to become too strong. Should be enough for
slightly milder lows, with lower 20s in southeast SD and teens in
northwest IA and southwest MN.

Wednesday will see light winds as they turn more southerly ahead of
the next approaching system. While this system is not quite as
strong as the Tuesday system there should be a little more moisture
to work with, especially in central SD, so some patchy light snow
will be possible there. The better chances will be during the
evening. Not planning on any accumulations over an inch right now,
but will be about the only time period to watch the next several

A weak ridge of high pressure aloft will spread into the area on
Friday with another upper level trough expected Saturday night into
Sunday. While there will not be a mention of any precipitation at
this time will keep an eye out for increasing confidence with
upcoming model runs. Temperatures Thursday into the weekend remain a
little above normal, but not expecting any real mild days.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 510 PM CST Mon Dec 10 2018

Upper level clouds will continue to stream overhead tonight with
the one minor aviation concern revolving around any potential fog.
Light winds and trapped residual boundary layer moisture would
point to at least some fog risk but most of the high res guidance
is not overly excited about this potential. Will leave some
mention in at KFSD and KSUX for now and monitor trends through the
evening. Otherwise, VFR conditions expected thru the period with
some light snow possible at KHON by late Tuesday afternoon.




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