Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 170454

Area Forecast Discussion
National Weather Service Sioux Falls SD
1054 PM CST Mon Jan 16 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 429 PM CST Mon Jan 16 2017

Upper low will move across extreme southeast Neb/northwest MO early
this evening before rapidly moving eastward to Indiana by 12Z
Tuesday. This is because a northern stream upper trough is moving
southward into our area helping to kick the southern stream low
eastward. Strong deformation exists in the near term across
northwest IA where a bulk of the precip currently resides. It will
have difficulty moving much further northward as mid level dry air
is filtering into locations which are north of our headlined areas.
This evening, some weak trowaling exists where a slightly enhanced
area of precip could linger in an axis from Jackson MN, to Spencer
IA, and southwestward toward near Sioux City. However through the
evening, cooler air aloft begins to rush in which will turn the
precip over from a FZRA threat to sleet/snow. In fact a band of 1.0
to 1.5 inches of snow could fall from Dixon county Nebraska,
northeastward to Spencer IA and Jackson/Windom MN this evening
where this trowaling exits. In addition, ice nuclei is abundant at
the top of the cloud depth which will aid in changing the precip to
snow. For this reason, will hasten the end of the ice storm warning
to 7 pm early this evening instead of midnight, and then from 7 pm to
midnight will go with a winter weather advisory to capture some of
this lingering snowfall this evening. Concerning temperatures, lows
will vary greatly from northwest to southeast. Where skies will be
most clear, and in fact pretty clear even right now, Huron will
bottom out near 5 degrees, compared to the upper 20s near Storm

Tuesday looks like a benign weather day with high pressure moving
over the central plains. Highs will generally be in the upper 20s to
lower 30s, except for some upper 30s in Gregory county. Winds will
be light.

.LONG TERM...(Tuesday night through Monday)
Issued at 429 PM CST Mon Jan 16 2017

Decidedly more quiet on the weather front in the medium range.
Ridging aloft with westerlies retreating to the north and gradual
amplification of western U.S. trough will set the stage for a longer
duration January thaw, perhaps a shade earlier than the period of
record climatological occurrence, but playing in the same ballpark.
Low level gradient not the strongest, so with the massive warming
aloft through Tuesday night, would expect a fairly strong elevation
signature to min temps along with a slight wind enhancement around
the Buffalo ridge, considering some modification for existing
snowcover inversion strength.  On Wednesday, perhaps a bit of fading
of sunshine from time to time, but other than a bit weaker low level
flow and the power of existing snowcover, see no reason to not
accept most of the area toward warmer guidance.  Thursday will
remain quite mild, but a bit more of a due southerly flow and
influence of wandering upper low moving into the central plains may
start to bring increased threat of developing stratus under elevated
warm layer as the day and following night progresses. Diurnal temp
ranges likely to become a bit squeezed, with even an outside chance
for a near record warm low around Friday or Saturday.

This upper low will spend a couple days wandering before becoming
loosely tied to the western trough and lifting northward across the
area this weekend, then wrapping up in some fashion with southern
end of trough wrapping northward by early next week.  General idea
of a slowdown in the upper pattern accepted, along with likelihood
of a lot of clouds lingering right into early next week along with a
persistence of mainly light precipitation chances at times.
Precipitation type could again become an issue, but a much higher
chance that temps at surface will end up a bit warmer through the
weekend with mainly a rain threat, perhaps dancing a tango with some
spotty light freezing rain, rather than much in the way of snow.
Cold air somewhat limited given the amplified and blocked up flow
pattern, but perhaps a bit better chance for snow by Monday. Above
normal temps will continue through Monday.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1049 PM CST Mon Jan 16 2017

Band of light freezing rain or freezing drizzle across southwest
MN and northwest IA will continue to dissipate over the next few
hours. Swath of MVFR and IFR low stratus will also slowly shift
eastward overnight, with clearing/VFR conditions expanding behind
it. Some patchy fog will also persist with the lower ceilings,
with some additional patchy fog possible near the KHON area late


MN...Winter Weather Advisory until midnight CST tonight for MNZ080-

IA...Winter Weather Advisory until midnight CST tonight for



LONG TERM...Chapman
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