Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 211132

Area Forecast Discussion
National Weather Service Sioux Falls SD
632 AM CDT SUN AUG 21 2016

.SHORT TERM...(Today and Tonight)
Issued at 422 AM CDT Sun Aug 21 2016

A cool start across the area under influence of high pressure.
Thermal recovery, however, should be formidable as surface ridge
shifts east, and moderation to off-surface temps allows readings to
reach the mid 70s in southwest Minnesota and Iowa Great Lakes area,
upper 70s to near 80 along I-29, and mid 80s toward south central
South Dakota. Sunshine should remain plentiful today, dimmed only a
bit by some thinning higher level clouds during the day.  Tonight
will continue to see the southerly gradient increase, likely enough
to get some slight non-diurnal trends to temps.  Models have a
strong consensus to development of pressure trough downstream of the
Buffalo ridge, suggesting winds should see a bit of ridge
enhancement by late night along with slowly rising temps.

.LONG TERM...(Monday through Saturday)
Issued at 422 AM CDT Sun Aug 21 2016

Upper flow turns southwesterly on Monday and Tuesday in advance of a
wound up upper low tracking east across the US and Canadian border.
Tight pressure gradient will allow for strong mixing and breezy
southerly winds across the region. Expect gusty winds peaking around
25 to 35 mph both afternoons. Much warmer temperatures will also be
in store as highs peak in the mid 80s to mid 90s. The southerly flow
will also be tapping into greater moisture, allowing dewpoints to
return to the 60s. The higher moisture will help keep RH values in
check, despite the strong winds. Not anticipating any fire weather
headlines at this point, but will need to keep an eye on conditions.

With the upper low moving into the northern Plains midweek, a
shortwave lifts northeast along the flow, through the forecast area
Tuesday night.  Additionally, a surface front arrives in central SD
Tuesday afternoon and slowly tracks east through the overnight
hours. A good amounts of instability developing ahead of the front,
along with increasing lapse rates but marginal shear, signal that a
few severe storms will be possible, but the overall outlook is
rather marginal. Storms will exit the area around midday Wednesday.

Cooler air filters back into the region behind the front, however
flow turns more zonal on Thursday, then southwesterly on Friday
ahead of another trough approaching from the west. Models coming
into better agreement in the timing of these features. Moisture
return late this week and the approaching trough will trigger
scattered showers and storms in south central on Friday afternoon,
which spread east Friday night and Saturday. Temperatures will
generally remain in the 70s for the second half of the week.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 632 AM CDT Sun Aug 21 2016

While conditions through 13-14z could support some patchy fog
development, it will most likely only appear in isolated areas as
patchy MIFG near waterways, and not lead to more widespread
visibility restrictions. VFR conditions expected to prevail
through 12z Mon. Largest aviation concerns will be with developing
low level wind shear tonight, as south to southwest winds increase
to 35 to 45 knots between 1-2kft AGL.


.FSD Watches/Warnings/Advisories...


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