Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 161135

Area Forecast Discussion
National Weather Service Sioux Falls SD
635 AM CDT Sun Jul 16 2017

.SHORT TERM...(Today and Tonight)
Issued at 322 AM CDT Sun Jul 16 2017

Slightly, and I emphasize slightly, cooler and drier will be in
place over the area today in the wake of yesterdays weak frontal
passage. Basically it looks like highs today will roughly be five
degrees cooler than those of Saturday. Southeasterly surface winds
will be prevalent across the area due to high pressure to the

A little worried about possible mid level clouds moving into the
area tonight that could impact northern lights viewing.  At this
point, I`ll only go with a scattered deck so should see enough of
the sky to view the northern lights.

.LONG TERM...(Monday through Saturday)
Issued at 322 AM CDT Sun Jul 16 2017

Closed low currently over northeast Colorado begins to affect our
forecast area late Monday, as it moves into the Missouri Valley as
an open wave. Main question at this point is how quickly the wave
would move across Nebraska, and potential effect on temperatures in
southwest parts of the CWA Monday. GFS/NAM remain more aggressive in
generating convection/associated cold pool in northeast Nebraska by
late Monday, though latest ECMWF has trended in that direction, just
a bit slower. Thus have scaled highs in our far southwest back a few
degrees, but still looking at highs in the 90s most areas. More mixy
southwest flow should allow dew points to ease back a bit during the
afternoon, especially in our dry western areas.

With the aforementioned wave and low level boundary sagging toward
the far northern CWA Monday night into Tuesday morning, could see
isolated to scattered storms develop over the area. At this time,
the severe storm risk looks low, as instability and shear over most
of the area are rather meager. This could change by later Tuesday
into Tuesday night, if storms develop along the lingering boundary
across the southeast CWA later Tuesday into Tuesday night. Steeper
mid-level lapse rates will increase instability along/south of the
boundary. In addition, upper level jet moving north of the area will
bring an increase in deep layer shear. Thus, cannot rule out some
strong to severe storms later Tuesday, although timing and location
of greater risk will ultimately be dependent on evolution of morning
activity across the region, and location of any resultant outflow

Temperatures Tuesday/Wednesday will be more dependent on convection,
though overall look to ease back into the mid 80s-mid 90s. Humidity
levels will remain high, though, especially with weak flow around
low level boundaries allowing for moisture pooling. Thus could see
heat indices climb into the mid-upper 90s, possibly approaching 100F
in some areas both days. Will have to monitor the next couple days,
but may need heat advisory headlines by midweek due to the prolonged
period of marginal 95-100F readings.

Late week into next weekend features dominant upper ridge across the
southern/central US, with strong west-northwesterly flow confined to
the northern tier of states. Could see further periods of scattered
storms through this period, generally favoring the nighttime/early
morning hours, though fair amount of uncertainty in timing/location
at this range. Daytime temperatures look to be less warm than the
early part of the week, but still generally near to above seasonal
normals in the 80s to near 90.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 633 AM CDT Sun Jul 16 2017

Vfr condtions expected throughout the entire forecast period. High
pressure to the east of forecast area will produce southeasterly
winds this afternoon and evening at the surface. A few more mid
level clouds may move into the area after 06z ahead of next storm




SHORT TERM...Heitkamp
AVIATION...Heitkamp is the U.S. government's official web portal to all federal, state and local government web resources and services.