785
FXUS63 KABR 280116 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
816 PM CDT Sat Jun 27 2026

.KEY MESSAGES...

- There is Enhanced (3 of 5) to Slight (2 of 5) to Marginal Risk (1
of 5) for severe weather tonight, mainly throughout and west of the
Missouri River valley region. Confidence is low on storm development
due to the mid-level thermal capping inversion in place. Convection
that does develop/move across central/north central South Dakota
tonight could have large hail of up to 2 inches in diameter and wind
gusts of 60 to 70 mph. A tornado or two cannot be ruled out,
particularly over western Corson/Dewey Counties.

- Western U.S. wildfire smoke (aloft) will overspread the region
tonight into Sunday morning; potentially sticking around for several
days while the steering flow winds are out of the southwest.

- There is Slight (2 of 5) to Marginal Risk (1 of 5) for severe
weather Sunday across the forecast area. Again, confidence is low
for storm development during the day, but once we move into the
evening and overnight hours, severe storms will be possible. Main
hazards are large hail up to 2 inches in diameter and wind gusts of
60 mph.

- Above normal temperatures for Sunday and into next week.
Temperatures are forecast into the 90s and dewpoints well into the
60s. This will push heat index values into the mid to upper 90s,
with increased risk for heat related illnesses.

&&

.UPDATE...
Issued at 808 PM CDT Sat Jun 27 2026

Quick update to mention the addition of Stanley county to the
TOR Watch per coordination with SPC. Starting to see increasing
development to the west of that area and with the environment
showing increasing low level SRH/Shear with the developing low
level jet, along with lower LCL heights, the potential for
tornadoes does exist as storms approach our area. Storms do
appear to be taking more of a linear look, which may limit the
potential some, but with the environment in place (and 25kts of
0-3km bulk shear) the possibility is there.

UPDATE Issued at 640 PM CDT Sat Jun 27 2026
Updated for 00Z Aviation discussion below.

.UPDATE...
Issued at 532 PM CDT Sat Jun 27 2026

No significant changes to the going forecast this evening, with
minor adjustments to the PoPs/Sky to account for the latest
forecast trends. Expect to let the Wind Advisory go at 7pm, with
the 35-45mph gusts expected to diminish over the next few hours.

Still looks like a primed environment for storm development in
western SD and have seen one cell develop in Mead county, which
could be one of the initial storms to make it into our area as
it moves to the northeast. Any storms that stay discrete in
northeast SD have the potential to produce all severe weather
hazards. Based on current storm movement and latest WoFS runs,
would expect the storm(s) to be nearing the Corson/Dewey county
area in around 2 hours. The TOR Watch for Corson/Dewey county
goes until 05Z.

The next area of focus is farther south where we continue to
see increased convergence across Haakon/Jackson counties, where
satellite has shown a couple attempts at development thus far,
but nothing has sustained itself thus far. WoFS highlights
uncertainty in the coverage of development in this area, with
some runs having little to no development and others having a
few good cells developing and moving into our area in the 2-3hr
range. Will be continuing to watch that area on satellite, as
currently there isn`t much of a CU field, likely due to the
strong but likely weakening CAP in that area. That leaves that
area in a more conditional severe threat and will need to
monitor trends with SPC for future watch needs, which may be
associated with even further upstream convection.

&&

.DISCUSSION...
Issued at 137 PM CDT Sat Jun 27 2026

At 1 PM CDT, skies are mix of sun and clouds. There are a handful of
showers/weak thunderstorms around the forecast area early this
afternoon, due primarily to weak diffluent flow aloft and adequate
mid-level moisture/steep lapse rates. Temperatures are warming
through the 70s, on their way to highs in the 80s. Winds are
southeast around 10 to 25 mph with gusts 30 to 40 mph throughout and
east of the James River valley region. West of said region,
southeast winds are stronger, 25 to 35 mph with gusts 40 to 50 mph.
A wind advisory remains in place through early evening for these
strong winds.

In the current southwest flow trajectory (that`s expected to persist
for nearly the entire forecast period), a plume of (elevated)
wildfire smoke stemming from an intermountain west wildfire is
progged (HRRR) to stream northeast into the CWA this evening,
persisting through Sunday. It could be sticking around all or some
portion of the CWA for quite a while (potential impact on temps/heat
concerns?), if the upper level steering flow winds are just right to
keep this wildfire smoke plume streaming up into this CWA.

The risk for severe weather, enhanced (3 of 5), slight (2 of 5) and
marginal (1 of 5), persists this evening through late tonight,
especially west of the James River valley region of the CWA. 15+C
dewpoint air at 850hpa will be in place, so no lack of
instability/moisture for severe weather. Mid-level lapse rates are
progged at 7.5+C overnight, and the deep layer shear is progged
between 35 and 45 knots. If the warm 700hpa temps (+11C to +13C)
over the western/southwestern forecast zones hold, will have to wait
for convection that forms over wrn/swrn South Dakota and nwrn/nc
Nebraska to move into the western (west river) forecast zones much
later this evening. Throw in a nocturnal low level jet and there is
the potential, for organization/upscale growth into one or more
(bowing) line segments overnight. Initially, hail of 1-2in in
diameter are possible with any storms that can punch through the
Capping inversion (quite strong on the 18Z KABR RAOB), with perhaps
a gradual transition to more of a wind threat late, provided cold
pool/shear organization can land in goldi-locks territory.

Reset the playing field for Sunday, and similar severe weather
potential is in play, especially as surface trofs/lows/fronts all
start making their way east across the CWA from late Sunday
afternoon through early Monday morning. The latest SPC Day 2
Convective Outlook has pulled the slight risk all the way back to
near Faith, SD, owing perhaps to the location of said surface wind-
shift/troffing features heading into Sunday peak heating. Currently,
Sunday afternoon/evening deep layer shear/instability is progged to
be higher than this afternoon`s/tonight`s parameters showcase.

The active southwesterly flow pattern aloft appears to be in play
throughout the 7-day. Upper level ridging over the upper and mid-
Mississippi River valley is progged to ever so slowly begin
retrograding back to the west and north, especially during the
second half of the period (Wednesday through Saturday), eventually
cutting off the active shortwave-train that southwest flow can bring
and turning the region into more of a "ring of fire" type of set-up
where mid-levels become too capped and most convection occurs/moves
north and east around this CWA. This will translate into several
days of above normal high temperatures running from the upper 80s to
potentially the upper 90s, provided elevated smoke doesn`t prohibit
insolation. Will continue to monitor the heatrisk output and
apparent T values in the forecast rolling into next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 631 PM CDT Sat Jun 27 2026

Terminals KABR,KATY,KPIR,KMBG

Primary concern is the convective potential this evening into
the overnight hours. The potential for convection is highest at
KMBG/KPIR late this evening and into the first part of the
overnight hours, as storms move into the area from western SD.
Did add TEMPOs to those sites during the time with the greatest
confidence, but there still remains uncertainty on both timing
and intensity of the storms. Will fine tune over the coming
hours. Expect any showers and thunderstorms to push east through
KABR/KATY during the overnight hours and handled that with
PROB30s due to the uncertainty on timing/location. Behind the
convection, models are hinting at an increased potential for low
stratus staying in place through at least the first half or all
of the morning, then diminishing from west to east through the
day. This low stratus could limit the severe weather potential
tomorrow, with the best chance coming after the TAF period and
during the overnight hours.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.

&&

$$

UPDATE...SRF
DISCUSSION...10
AVIATION...SRF