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Area forecast discussion 
National Weather Service Sioux Falls South Dakota
609 am CDT Sat Aug 29 2015

Short term...(today and tonight)
issued at 347 am CDT Sat Aug 29 2015

Stratus continues to hold over the southeastern portions of our County Warning Area
very early this morning. Models differing on how quickly this pulls
off to the east...but the low clouds seem to be tied to areas with a
light northeasterly flow...so used the low level wind field to time
its departure...in the middle to late morning. Have not seen any fog
formation at this point...though still a possibility with abundant
near surface moisture and light winds so kept it in the forecast
through the morning hours. Otherwise...surface and upper level
ridging build into the region today...providing for relatively light
winds and warming temperatures. Highs are looking to range from
around 80 from the Interstate 29 corridor eastward...to near 90 over
south central South Dakota.

With high pressure continuing to dominate across the region...winds
will again be light tonight...especially in our east...and models
again hinting at fog and possible stratus formation east of
Interstate 29. Lows will be a little milder...generally lower 60s.

Long term...(sunday through friday)
issued at 347 am CDT Sat Aug 29 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 12z tafs through 12z Sunday morning)
issued at 603 am CDT Sat Aug 29 2015

An area of IFR stratus is situated south and east of Yankton South Dakota to
Windom Minnesota line...with areas of IFR visibilities with fog
in locales generally from the Interstate 29 corridor and eastward.
These low clouds and visibilities are expected to improve after
15z. Otherwise...VFR conditions expected through this evening.
Could see areas of fog develop again after 09z tonight east of I
29.

&&

Fsd watches/warnings/advisories...
South Dakota...none.
Minnesota...none.
Iowa...none.
NE...none.
&&

$$

Short term...jm
long term...
aviation...jm

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