459
FXUS63 KABR 271337 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
837 AM CDT Sat Jun 27 2026

.KEY MESSAGES...

- A wind advisory has been issued for much of central South
  Dakota, for winds gusting 40-50 mph.

- There is Slight (2 of 5) to Marginal Risk (1 of 5) for severe
  weather mainly this evening and overnight. Confidence is low
  on storm development due to very warm temperatures above the
  surface. If storms do form, it will most likely be in the
  evening to overnight hours. These storms could have large hail
  of up to 2 inches in diameter and wind gusts of 60-70 mph,
  and a tornado or two developing cannot be ruled out.

- There is a Marginal (1 of 5) risk for severe weather Sunday
  along the ND/SD border. 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 and isolated 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 827 AM CDT Sat Jun 27 2026

Made a few adjustments to the PoPs over the next 4-8 hours to
account for the recent reflectivity bloom on radar. Returns are
likely strong enough to indicate rain reaching the ground. Can`t
imagine most of the areas that experience light rain this
morning/the first half of today won`t see more than a trace to a
hundredth or two of an inch. No other changes made to the today
period forecast at this time. Updates are out.

UPDATE Issued at 636 AM CDT Sat Jun 27 2026

UPDATE for 12Z Aviation discussion/TAF issuance

&&

.DISCUSSION...
Issued at 141 AM CDT Sat Jun 27 2026

There is a 15-25% chance for some scattered showers into the morning
before things clear up into the early afternoon. As this is
happening, a high surface pressure is settles over the Great Lakes
region today and lower surface pressure to the west over MT/WY. This
will help to tighten the pressure gradient over SD a bit, and
increase winds Saturday aloft. With lapse rates increasing during
the mid-morning through the afternoon, these stronger winds will be
able to get to the surface. Southeasterly winds will be moving into
SD with a 50-70% chance for the winds to be sustained at or above 30
mph with a 40-60% chance for gusts of 45 mph or more mainly in north
central SD and areas west of the Missouri River. A wind advisory had
been issued for this area because of these winds. These strong
winds could make driving difficult, especially for high profile
vehicles.

The southeast winds will be pushing lots of moisture into SD today
and with instability building through the day (NAM has MLCAPE values
in the 2000-3000 J/kg over central SD during the evening). While
there is a good environment for severe storm development, models are
showing higher CIN values through the afternoon and into the evening
over central and northeastern SD, which will helps to show the cap
in the atmosphere that will stop storms from developing. Weaker CIN
values to the west could cause storms to develop in western SD and
then move into/develop over central SD during the late evening into
the overnight hours when CIN values weaken over central SD. High-res
models show some scattered storms moving into central SD during the
late afternoon but not lasting too long. Then more storms move in
during the late evening/early overnight hours with a few models
showing a few more storms trying to develop over central SD
overnight behind the earlier cells as they move east.

There is a slight risk (level 2 out of 5) for severe storms over
central SD today, and a marginal risk (level 1 out of 5) over
northeastern SD and west central MN. While there is lower confidence
in the timing of these storms due to the cap of warmer air aloft,
the main threat timing looks to be during the evening and overnight.
With stronger lapse rates and shear being forecast, large hail (up
to 2 inches in diameter) and strong winds of 60-70 mph will be
possible in the storms. Additionally, with the shear available, a
tornado or two developing, mainly over areas west of the Missouri
River, cannot be ruled out. With the storms occurring overnight and
moving east, some lingering weak storms and showers will be possible
Sunday morning over northeastern SD and west central SD as the
storms dissipate or move out of SD.

Sunday, the surface low is forecast to move over western SD and will
create a similar environment for severe storm development over
central and northeastern SD. While there will be higher CAPE and
shear values to aid in severe storm development, the CIN again looks
to be high, with a stronger cap to stop storm development during the
afternoon into the evening. While confidence in timing is low again
on Sunday, models are hinting at a weakening cap during the late
evening and overnight hours which would allow for storms to develop
during those times over central and northeastern SD. There is a
marginal risk (level 1 out of 5) for severe storms. The main threats
in these storms will be hail up to 1 inch and winds gusting up to 60
mph.

While the surface low is moving into SD Sunday, a high pressure is
setting up to the east . This high pressure and southerly winds will
help to move warmer temperatures into SD during the end of the
weekend into the beginning of the work week. Models have scaled back
on how hot eastern SD will be getting compared to previous runs,
moving the heat to the east. While the models have scaled back
slightly, it will still be hot out Sunday and Monday. Heat index
values will be in the low to mid 90s Sunday afternoon areas in the
James River Valley and to the east, and Monday will be in the low to
upper 90s east of the Prairie Coteau. In addition to the heat trying
to move into SD on Sunday, some models are forecasting a little bit
of smoke from the wildfires to the southwest to move in Sunday
morning behind the storms. At the moment, this smoke looks to stay
aloft over western and north central SD, and could cause some
milky/hazy looking skies in north central SD Sunday morning after
the storms move through.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 636 AM CDT Sat Jun 27 2026

Terminals KABR,KATY,KPIR,KMBG

We have light showers mainly over north central SD (MBG) to
start out the period. These, with the potential for brief MVFR
ceilings, will be near PIR/ABR by 15Z. VFR conditions and mainly
dry conditions will give way to evening showers and storms over
central SD with the highest potential 04-08Z at PIR/MBG and
06-09Z at ABR where PROB30s were included with predominant
showers. Later issuances will be able to fine tune the timing
and threat. There is a slight risk (level 2 of 5) of severe
storms over MBG/PIR late this evening into the overnight hours.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 7 PM CDT /6 PM MDT/ this evening for
     SDZ003>005-009-010-015>017-033>037-045-048-051.
MN...None.

&&

$$

UPDATE...10
DISCUSSION...12
AVIATION...06