Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 221109

National Weather Service Sioux Falls SD
609 AM CDT Sun Sep 22 2019

.SHORT TERM...(Today and Tonight)
Issued at 249 AM CDT Sun Sep 22 2019

Surface boundary has finally sunk south and east of our area,
running from near Omaha northeastward into southeastern MN. Even so,
mid and high level clouds continue to stream into the area with
temperatures largely running in the 50s early this morning.

As we approach the daybreak hours, will watch for precipitation
chances to creep back from the south in the form of showers induced
by an area of strung out mid level forcing. Relatively high cloud
bases and a bit of a dry sub cloud layer should keep this activity
light with NW IA standing the best chance of measurable precip,
perhaps limited to sprinkles as you move northwestward. One last
area to watch for precipitation would be back across areas closer to
the MO River Valley later this afternoon as soundings exhibit some
very weak uncapped instability atop an inverted V profile. Although
with pretty good upper level subsidence taking over on the back side
of the closed low by this point, may very well go unutilized.

Northwest surface winds behind the front today have already started
to usher in cooler and less humid air. Combine this with increased
cloud cover for at least the first half of the day and high
temperatures will generally run in the upper 60s to lower 70s with a
more fall-like feel in the air.

Overnight lows will again drop closer to their seasonal normals, or
upper 40s to lower 50s. With lighter winds and clear skies, may see a
bit of fog in lower lying areas.

.LONG TERM...(Monday through Saturday)
Issued at 249 AM CDT Sun Sep 22 2019

Southerly surface winds return for Monday as shortwave ridging
slides overhead with surface high pressure to our south. Expect
mostly clear skies and above normal temperatures. In fact, leaned
close to the 90th percentile for afternoon highs, which match
closer with the various ensemble means.

Another warm day Tuesday ahead of an approaching cold front. Again
adjusted temperatures closer to the 90th percentile with the various
deterministic models generally running toward the bottom of their
respective ensemble envelopes. Clouds increase by late afternoon
with scattered thunderstorm development possible east of I-29
induced by the previously mentioned front. Given shear and
instability parameter spaces, a few strong to severe storms would be
possible and thus an appropriately placed marginal/slight risk from

The region sits in an increasingly collapsed northwest flow regime
aloft for Wednesday and Thursday with quiet conditions and
temperatures within a few degrees either side of their seasonal

By late week, upper level wave digs into the intermountain west,
turning our flow aloft out of the southwest. This could set the
stage for another somewhat active period. First chances come as
early as Thursday night on the initial push of warm advection.
Surface boundary collapses in by Friday and Friday night and will
allow for additional convection chances, although its placement
still somewhat uncertain. Temperatures continue to run from the
upper 60s to near 80.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 605 AM CDT Sun Sep 22 2019

Light rain showers or sprinkles will move thru areas mainly south
of I-90 this morning before exiting thru NW Iowa this afternoon.
Impacts from this activity are expected to be fairly minimal.
Otherwise VFR conditions expected thru the period with NW winds
generally under 10 kts for the daytime hours, turning more
southerly at night.




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