460
FXUS63 KABR 240642
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
142 AM CDT Fri Jul 24 2026

.KEY MESSAGES...

- There is a Marginal (level 1 of 5) Risk for isolated to
  scattered (20-30% chance) severe storms to develop in north
  central SD this afternoon and move east this evening. The
  primary threats will be 1 inch hail and 60 to 70 mph wind
  gusts. These storms are most likely to be limited to the
  highway 12 corridor and locations north.

- Increasing temperatures today, with peak heat for the weekend.
  Temperatures Saturday/Sunday 10 to 20 degrees above normal
  (upper 90s to low/mid 100s). Less intense, but still above
  average heat for next week.

&&

.DISCUSSION...
Issued at 126 AM CDT Fri Jul 24 2026

Stratus lingers east river this morning, maybe a few pockets of fog
too, and still somewhat comfortable temperatures and humidity.
Focus for the next several days include a severe weather threat for
later this evening and multi-day heatwave.

The 500mb pattern continues to be defined by broad upper ridging
across the center of the country. Currently were under northwest
flow around the high, which allows for this very subtle wave this
evening. The ridge axis builds overhead with increasing heights for
the Northern Plains though we retain a northwest component with the
ridge axis along the Dakota/MT/WY border. The upper high gradually
retrogrades into a more traditions 4-Corners high with a deepening
trough across the eastern CONUS.

700mb temperatures on the increase today out ahead of the shortwave,
and we`ll get up to around +9 to +12C today.  Those temperatures
continue to ramp-up for the weekend, +13C to +18C in the GFS (which
mixes well past this level both days) but +12C to +16C in the other
deterministic models. This is roughly 2 standard deviations above
climo, 500mb temperatures are also a standard deviation above climo.
While we`ll see "relief" from this extreme heat, 700mb temperatures
are still a standard deviation above climo for all of next week.
Thus temperatures will average this weekend 10F to 20F degrees above
climo, and 5F to 15F for next week. The one thing that we cant
quantify, and remains as a generalization at this point is what
impact high smoke will have on temperatures.

CAMS still attempting to generate storms along a boundary up across
northwest/north central South Dakota late this afternoon/evening.
Convective modus operandi is something like high based storms, up
around 10kft, with skinny CAPE and dry atmosphere up above 500mb.
Thus, it`ll be outflow winds and with such a strong CAP, they`ll
probably blow themselves out despite moving relatively quickly with
40-60kts in the convective layer.  As such, not expecting much
overall moisture potential. HREF member postage stamps 24 hour
rainfall not showing much for the CWA save an isolated streak or two
of 1/4" to 1/2".

Side note. Looks for some Coteau winds with a southwest oriented low
level jet. 1/2 km winds are about 40kts tonight.

Very deep mixing despite warm temperatures aloft, can`t rule out an
isolated daytime driven storm Saturday evening, but more likely is
the potential for elevated convection associated with a plume of
moisture aloft coming around the high from the Intermountain West.
That same wave is responsible for the Day 3 risk area in
Minnesota which features more of a pulse convection regime under
weaker although unidirectional steering flow.

As for heat headlines, still a little too soon for an advisory, but
deterministic NBM is well into criteria both Saturday and Sunday.
25th-75th percentile ranges in highs is 3-8F for both days though
this is removing the higher biased (overly mixy) GEFS. 25th-75th
range in NBM dewpoints also indicates quite a bit of uncertainty at
13 to 20F (mid 50s to low 70F). Aside from showing a likewise overly
mixy GEFS bias, additional uncertainty added as corn is at its
potential peak ET, but being tempered by the regional lack of
consistent moisture. Looking at just an EC/Canadian ensemble
suggests dewpoints may end up being a little underdone in the NBM.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 126 AM CDT Fri Jul 24 2026

Terminals KABR,KATY,KPIR,KMBG

Low stratus and some potential fog on the west side of the stratus
will be the primary concerns for the next 12 hours. MVFR to VFR
stratus has been expanding over eastern SD over the last few hours
and expect it to hold on for much of the night based on the latest
HREF probabilities. Even showed a lowering of KABR/KATY to IFR
ceilings towards daybreak based on the HREF probs of IFR ceilings in
the 60-80% range. West of the stratus, have see a little fog near
Gettysburg and could see patchy ground fog, so have mentioned that
for KMBG/KPIR. Confidence is lower on widespread lower visibilities
due to the light southerly winds remaining up through the night.

Focus then turns to thunderstorm potential for northern SD late this
afternoon and into the evening hours. Confidence is low on
development, due to the potential for warm air aloft to limit
coverage of storms, but did provide a PROB30 mention at KMBG (most
likely) and also KABR.

&&

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

&&

$$

DISCUSSION...07
AVIATION...SRF