984
FXUS63 KABR 291120
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
620 AM CDT Wed Jul 29 2026

.KEY MESSAGES...

- High temperatures today will be in the upper 90s to low 100s over
central and north central South Dakota. Heat index values up to 102
will be possible. A Heat Advisory is in effect from 12 PM CDT
through 8 PM CDT today for that area.

- Western wildfire smoke may impact visibility at times across the
region through this evening. Smoke may drop air quality to the point
of impacting those sensitive to smoke.

- A Marginal Risk (level 1 of 5) for severe weather is in place over
parts north central South Dakota west of the Missouri River this
evening. Wind gusts of 60 miles per hour will be the main severe
threat.

- A Marginal Risk (level 1 of 5) for severe weather is in place
Thursday. The main hazard will be wind gusts of 60 mph and hail of
one inch in diameter.

&&

.UPDATE...
Issued at 620 AM CDT Wed Jul 29 2026

UPDATE for AVIATION discussion

&&

.DISCUSSION...
Issued at 245 AM CDT Wed Jul 29 2026

Main forecast focus today is the continuation of abnormal heat
thanks to a broad upper-level ridge allowing a warm airmass into the
region. Over central and north central South Dakota specifically,
heat index values will top out over 100 degrees this afternoon, and
Heat Risk will reach the Major category in some places. With these
factors in mind, a Heat Advisory has been issued for this afternoon
over central and north central South Dakota. Admittedly parts of the
area under the advisory are a bit borderline and/or spotty for
reaching Heat Advisory criteria of 100 degree apparent temperatures.
One potential failure point for temperatures today will be the
addition of smoke across the region originating from wildfires in
the Pacific Northwest. Smoke is mainly expected to remain aloft
(still having an impact on temperatures), although some near-surface
smoke remains possible. Concentrations at the surface may cause some
minor visibility  reductions and push air quality up to Moderate
levels (which corresponds to Air Quality Index values of 50-100).
This level of air quality means that mainly those sensitive to smoke
will be impacted.

Beginning this evening into tonight, a severe weather threat will
emerge over parts of north central South Dakota, mainly west of the
Missouri River. The latest high-resolution guidance keeps most of
the storms to the west until the late evening to early overnight
hours. By the time storms reach the Aberdeen CWA, they will
encounter an environment that will not be particularly supportive of
storms. A lack of strong shear (<30 knots) and CAPE of around 1000
J/kg will likely struggle to maintain storms, and storms that make
it may dissipate shortly after crossing the CWA border. Naturally
with collapsing storms, wind will be the main severe threat. DCAPE
values in particular will be quite high, with high-res model
guidance resolving upwards of 1500 J/kg over the area. Fairly strong
low-level lapse rates (Near-dry adiabatic lapse rates all the way up
to roughly 5-6 km in model soundings) may also be present, allowing
for easy access to the surface. Diurnal cooling may temper these
strong lapse rates depending on when storms arrive over the area,
but the threat likely remains. A Marginal Risk is in place to cover
this threat.

Showers and storms will continue from Wednesday night into Thursday
morning, spreading eastward throughout the morning hours. While
severe weather during that morning period can`t entirely be ruled
out, chances for severe weather increase in the Thursday afternoon
to evening period. Wind will once again be a threat, although
perhaps under a less impressive DCAPE environment than on Wednesday.
The persistent cloud cover will also limit the diurnal heating and
subsequently low-level lapse rates. Hail is also a possible threat,
but storms will again be dealing with shear up to roughly 30 knots,
which may make it difficult. MUCAPE values do reach around 2000 J/kg
however, so that will be one thing working in favor of storm
development and maintenance. Another Marginal Risk is in place
Thursday, this time covering the entire Aberdeen CWA.

As the shortwave influence exits the region, it will begin to deepen
over the eastern CONUS. The upper-level ridge will therefore become
more positively tilted, still allowing for a warm airmass to sit
overhead. The presence of the trough to the east may create a bit of
a gradient in temperatures over the forecast region however. This
will likely result in near-normal temperatures (mid-80s) over
northeastern South Dakota and western Minnesota and above normal
temperatures (90s) over central and north central South Dakota.
Ensembles then show the potential for an upper-level trough to move
through early next week, with the base of the trough located over
the Northern Plains. This may provide the next chances for rain over
the area, although at this time range it is difficult to pinpoint
exactly. Currently confidence is highest in precipitation to the
north of the CWA in North Dakota based on the location of the jet
streak in ensemble forecasts, but it will likely dip far enough
south to support some development south of the state line as well.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 620 AM CDT Wed Jul 29 2026

Terminals KABR,KATY,KPIR,KMBG

Expect mainly VFR conditions through the next 24 hours. The
main concern will be near surface smoke dropping visibility to
6SM at times. At 11Z all of the air quality reporting platforms
were in the Moderate (yellow) category across the forecast area.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory from noon CDT /11 AM MDT/ today to 8 PM CDT /7
    PM MDT/ this evening for SDZ003-004-009-015-016-033>037-
     045-048-051.
MN...None.

&&

$$

UPDATE...06
DISCUSSION...BC
AVIATION...06