Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 162123
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
323 PM CST Tue Jan 16 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 323 PM CST Tue Jan 16 2018

After several days of very cold weather, a rapid warm up is
coming. A high pressure ridge was located near YKN at 20Z. The
ridge is expected to continue to move southeast into Nebraska
overnight. Clear skies and light winds can be expected very early
this evening over most of the forecast area. As the high continues
to drift to the southeast, winds will gradually increase out of
the west or southwest - first from south central South Dakota into
southwestern Minnesota and then after midnight over northwestern
Iowa and northeastern Nebraska. As the winds increase, temperatures
will become steady and then slowly rise the remainder of the
night. The coldest readings overnight will be in northwestern Iowa
where radiational cooling will persist the longest and lows will
be from -3 to -6. West of the James River, where lows will be
reached early this evening, lows will remain above zero. The other
concern is the increasing winds expected east of the Buffalo Ridge
due to mountain waves. As wind at 925 mb increase over 25 kts,
downslope winds will also increase with gusts over 30 kts possible
late tonight. This will also help temperatures warm with
temperatures near 10 degrees by sunrise on Wednesday east of the
Buffalo Ridge.

Gusty winds will continue near the Buffalo Ridge much of the day
although by afternoon conditions for downslope winds will become
less favorable allowing for some decrease in winds. Otherwise,
with mostly sunny skies and westerly winds, highs across the area
will range from the upper 20s in the Big Sioux Valley to around 40
in south central SD.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 323 PM CST Tue Jan 16 2018

In the long term, the focus is on unseasonably warm weather
expected Thursday and Friday and then precipitation chances late
in the weekend.

A ridge will build over the area for the end of the week.
Persistent westerly flow will continue to bring warm air into the
area. While the snow pack is rather shallow and does not contain a
lot of moisture, expect that temperatures Thursday will be a
somewhat impacted by the snowcover with highs from the upper 30s
in much of northwest Iowa and southwest Minnesota to around 50 in
south central South Dakota. Expecting at least some of the
snowpack to disappear by Friday. And an approaching front will
also enhance mixing so that Friday should be the warmest day of
the week. High will be 15 to 20 degrees above normal - from the
lower 40s along the Buffalo Ridge to the lower 50s in the Missouri
Valley.

The other concern this period is the potential precipitation
system for the late weekend. MOST GEFS solutions as well as all
deterministic models now show an upper wave and associated cyclone
moving from the Rockies toward the Great Lakes. While many models
are now showing over 0.25" of QPF with this system - where that
precipitation will fall is very uncertain. While confidence has
increased that there will be at least light precipitation in
northwestern Iowa, confidence for any precipitation is lower in
southeastern South Dakota. And confidence for heavier
precipitation remains low across the entire area. So it remains
far too early to talk about any snowfall amounts. Whether this
system does have a significant impact on the region or not,
temperatures early next will be around seasonal normals in the
20s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1129 AM CST Tue Jan 16 2018

MVFR scattered clouds persist for a few hours this afternoon, then
VFR conditions prevail into Wednesday.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...Schumacher
LONG TERM...Schumacher
AVIATION...Dux



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