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Area forecast discussion 
National Weather Service Sioux Falls South Dakota
405 am CDT sun Aug 30 2015

Short term...(today and tonight)
issued at 401 am CDT sun Aug 30 2015

Again seeing stratus and areas of fog across the eastern portions of
the County Warning Area early this morning. Though models differing just a bit on
how quickly this fog/stratus will erode...the general theme is for
it to decrease between 15z and 18z. Otherwise...upper level ridging
will continue to dominate across the region today...and will have an
increasing southerly flow as a surface trough begins to push into
the western High Plains. This will result in a tightening gradient
across the region...and will see southerly winds pick up through the
afternoon. While it will be mostly sunny...air quality forecast
guidance is suggesting that there could again be some smoke aloft
which would result in hazy skies. In the increasing southerly flow
it will be warmer today...with coolest readings through northwest
Iowa where stratus may persist the longest...with highs topping out
around 80. To the west...highs expected to reach the lower 90s
through our south central South Dakota zones.

Winds will remain fairly Stout tonight through our north and
west...with lighter winds through the lower MO River Valley into
northwestern Iowa. Some models...with the NAM the most
pronounced...suggesting some stratus/patchy fog development in our
southeast later tonight...though thinking that it will not be as
extensive as recent nights. Lows will be fairly the middle
and upper 60s.

Long term...(monday through saturday)
issued at 401 am CDT sun Aug 30 2015

Patchy fog across the eastern forecast area will lift quickly Sunday
morning...stratus across portions of northwest Iowa may be a bit
slower to mix out in the morning. Otherwise...southerly winds will
be on the increase through day...becoming windy across south central
South Dakota where the pressure gradient tightens up due to strengthening low
pressure in western North Dakota. However...the warm air
advection...copious sunshine and strong mixing west of i29 will
allow temperatures to soar into the middle 80s to lower 90s. Further
east...some lingering morning clouds and weaker mixing will keep
temperatures slightly cooler in the lower 80s.

For the first half of the work week...temperatures will be
seasonally warm with generally dry conditions prevailing. The
aforementioned system in the northern plains slides east and
squashes the upper ridge on Monday. A diffuse frontal boundary will
approach the area Monday evening and overnight...but with weak lift
and poor upper support...precipitation chances look slim. Will leave
some very low end thunderstorm chances in the evening...but
confidence is pretty low.

Upper flow remains southwesterly through the end of the work
week...with several very weak waves likely to impact the area. With
no real confidence in any particular solution...have removed most of
the very spotty probability of precipitation from the allblend middle week. By late week
however...models begin convening on a solution of bringing a
slightly more substantial wave into the Central Plains so will leave
some low end probability of precipitation Friday...ramping up into chances for Saturday.


Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1038 PM CDT Sat Aug 29 2015

MVFR stratus is beginning to stream north to northwestward across
northwest Iowa along the low level flow. This trend will continue
all night. Therefore am expecting IFR to MVFR conditions to
prevail for many areas generally along and east of the Interstate
29 corridor. The stratus could first affect ksux shortly after
06z. Kfsd is quite a that they could be on the
edge of the northward building stratus late tonight. For that
reason...will include a tempo IFR group for visibility around
sunrise Sunday.


Fsd watches/warnings/advisories...
South Dakota...none.


long term...

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