Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 282157
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
357 PM CST Mon Nov 28 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 357 PM CST Mon Nov 28 2016

Cut off upper low moves very little over the next 24 hours or so
resulting in continued cloudy conditions with the potential for
light precipitation across the north as waves rotate around the low
pressure system. With cloudy conditions, diurnal range should be
fairly small. As temperatures fall tonight, lower portions of
thermal profile becomes cool enough to support light snowfall. Once
again, expect heaviest accumulations of up to an inch across central
South Dakota with lesser amounts to the south and east.

As profiles warm throughout the day on Tuesday, expect precipitation
to mix with and eventually change back over to a rain.  Have raised
wind gusts, especially with higher pops tomorrow afternoon. With 925
hpa temps remaining around -4 C, expect highs in the upper 30s to
near 40.

.LONG TERM...(Tuesday night through Monday)
Issued at 357 PM CST Mon Nov 28 2016

The main weather impacts within the intermediate and long term come
a bit front-loaded, dealing with the persistent precipitation with
immense closed upper low wobbling on its exit from the northern
plains. Precipitation will continue to be distributed unevenly
around the circulation, with lower level frontogenetic axis wrapping
southward behind mid-level circulation which will drift back toward
southern MN by Tuesday evening.  Precipitation type should be
primarily in the form of snow once transition really takes hold on
later Tuesday afternoon and evening, and it is honestly difficult to
see how will get much of a return to rainfall once this occurs. Will
have complexity of some slightly warmer air aloft wrapping into the
upper circulation which will brush along the northeastern portions
of the CWA through Tuesday evening.  Main period of accumulating
snowfall looks to be from later Tuesday evening through early
Wednesday. The lift does remain somewhat lower in the column and the
thermal profiles do not scream efficiency on the relatively warmer
side of ice growth range. However, even with limitations to
efficiency and with some near freezing surface temps, an additional
inch or two likely for many areas north of I-90.

Eventually, the strength of the frontogenetic forcing will weaken
along with the trowal airstream by later Wednesday and Wednesday
night, and should see organization to any precipitation bands
shatter and dissipate by early Thursday across mainly southwest MN
and northwest IA.  Northwest winds will remain strong and gusty
through at least Thursday before starting to ease. Temperatures with
an abundance of clouds and winds should be fairly limited in diurnal
range, but should gradually widen a bit on the low temperature side
by Thursday night when get some readings falling back toward around
20, and Friday night when clearing at last takes hold and allows
with diminished gradient to have some lows in the teens. Will likely
have to drop some lows once snowcover from prolonged precipitation
event this week is defined.

Solutions have pulled a bit away from development of a stronger
southern stream wave and threat for strong system brushing the far
eastern CWA around late Sunday, and are more or less a jumbled
timing of more progressive waves passing across the area on Saturday
and early Sunday. Not enough confidence to lock on to any one
solution, so while some spotty light precipitation is not impossible
around Saturday night, too uncertain to incorporate into the
forecast at this point. Temps gradually will moderate closer to
normal over the weekend and early next week. GFS-tilted solution
would be a warmer solution by Sunday/Monday, while an EC-tilted
solution would have to keep an eye on deepening system well to the
east for a return westward shift trend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1105 AM CST Mon Nov 28 2016

IFR Conditions expected along and north of I90 today as low
pressure system moves from northeast South Dakota into eastern
North Dakota. Could see some scattered shower activity in this
area as well, temporarily reducing visibility at times. Northwest
winds will be gusty through the period, especially in shower
activity and during the daylight hours. VFR conditions further to
the south will gradually transition to MVFR as another lobe of
energy rotates around the upper low. This will result in MVFR
conditions developing around KSUX on Tuesday morning.

&&

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

$$

SHORT TERM...BT
LONG TERM...Chapman
AVIATION...BT



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