Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 270849
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
349 AM CDT Tue Jul 27 2021

.SHORT TERM...(Today and Tonight)
Issued at 348 AM CDT Tue Jul 27 2021

Latest satellite imagery reveals quiet conditions across the region,
with winds out of the south to southeast and current temperatures in
the upper 60s to mid 70s. Look for the heat to ramp up shortly after
daybreak as upper level ridging amplifies over the region. Much like
the past few days, the HRRR smoke model continues to show western
wildfire drifting overhead, which could put a damper on peak
heating. Nonetheless, with southwesterly winds in place throughout
the day, still think we will see highs in the mid to upper 90s, with
some areas west of the James River Valley reaching the low 100s. In
addition to this, dewpoints in the upper 60s to low 70s will cause
heat indices to soar into the low 100s for a vast majority of the
area. Thus, think the current Heat Advisory remains in good shape.

While convection looks to remain minimal throughout the day given
the large CAP in place, a few CAMs do suggest that an isolated storm
or two may be develop across SW Minnesota heading into the overnight
period. At this time, think most if not all of these storms would
remain elevated in nature, with damaging winds being the primary
hazard. SPC`s Day 1 Outlook does include a portion of our area in a
Slight Risk, however, as mentioned above, any development will be
largely conditional of the current CAP in place. Otherwise, look for
overnight lows to remain quite mild, with temperatures only falling
into the low to mid 70s.

.LONG TERM...(Wednesday through Monday)
Issued at 348 AM CDT Tue Jul 27 2021

Much like Tuesday, expect another hot day to prevail Wednesday, as
the aforementioned upper level ridge continues to strengthen.
However, there are still a few caveats that exist causing
Wednesday`s forecast to not entirely be slam dunk just yet. For
starters, think dewpoints may still be a touch too high, especially
if we can mix down a bit more, causing heat indices to be more
similar to Tuesday. Another complicating factor could be the cloud
cover/smoke transport, both of which could decrease our temperatures
by a few degrees, which has happened the past few days. Thus, after
collaboration with neighbors, have decided to continue with the
current Excessive Heat Watch on Wednesday for now, and will let the
day shift get one more final look at the trends before any headline
decision are made. Nonetheless, we encourage you to take precautions
if heading outdoors!

Should start to see some relief Wednesday night as a weak cold front
dives across the area. While isolated showers and storms are
certainly possible, accumulations look to remain less than a quarter
inch at best.

Look for dry conditions to prevail behind the cold front Thursday,
with highs much more seasonable, as temperatures only climb into the
mid to upper 80s. Otherwise, expect unsettled weather to return to
the forecast heading into the weekend, as upper level ridging to our
west places the region in a NW flow regime. Given that the finer
scale details could still substantially chance between now and then,
have opted to continue with model blend of PoPs for now until higher
confidence is achieved. It is worth noting, however, that
temperatures during this time will remain seasonable, with afternoon
highs in the 80s and overnight lows in the 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1108 PM CDT Mon Jul 26 2021

Just shy of needing a few hours mention of low-level wind shear
tonight for KHON/KFSD/KSUX, but fairly marginal at this point as
likely surface winds are a bit underpredicted. Winds could be
briefly gusty in the morning as this off-surface gradient mixes
into the PBL, but should even out to lighter values by midday.
Looks fairly capped, and any minor convective threat should be
after 00z/28 toward southwest MN.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory from noon today to 9 PM CDT this evening for
     SDZ038>040-050-052>071.

     Excessive Heat Watch from Wednesday afternoon through Wednesday
     evening for SDZ038>040-050-052>071.

MN...Heat Advisory from noon today to 9 PM CDT this evening for
     MNZ071-072-080-081-089-090-097-098.

     Excessive Heat Watch from Wednesday afternoon through Wednesday
     evening for MNZ071-072-080-081-089-090-097-098.

IA...Heat Advisory from noon today to 9 PM CDT this evening for
     IAZ001>003-012>014-020>022-031-032.

     Excessive Heat Watch from Wednesday afternoon through Wednesday
     evening for IAZ001>003-012>014-020>022-031-032.

NE...Heat Advisory from noon today to 9 PM CDT this evening for
     NEZ013-014.

     Excessive Heat Watch from Wednesday afternoon through Wednesday
     evening for NEZ013-014.

&&

$$

SHORT TERM...SSC
LONG TERM...SSC
AVIATION...Chapman


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