211
FXUS63 KABR 100228 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
928 PM CDT Tue Jun 9 2026

.KEY MESSAGES...

- There is an Enhanced Risk (Level 3/5) for severe storms for
  all of central and northeastern SD into west central MN this
  afternoon through tonight. Main threats include wind gusts of
  75+ mph, large hail (2+ inches in diameter) and tornadoes
  (EF2+ possible).

- There is a Marginal Risk (Level 1/5) for isolated severe
  storms Wednesday afternoon and evening along and east of a
  line from Britton to Brookings. Hail, one inch in diameter,
  and 60 mph gusts are the main threats, although the strongest
  convection is most likely to occur east of the Aberdeen
  forecast area.

- Cooler temperatures arrive for the rest of the week and into
  the weekend. Highs beginning Thursday will be in the mid 70s,
  near- normal to just below normal for this time of year.

&&

.UPDATE...
Issued at 915 PM CDT Tue Jun 9 2026

Discreted cells, originally, have lined out along a strong cold
front pushing through the Missouri River valley. Expecting a few
more strong updrafts capable of large hail, especially if there
are anymore cell mergers like what just happened in the
Pierre/Ft Pierre, and damaging winds. A brief isolated tornado
is also possible. Over the next 3-6 hours, this line of storms
is expected to move into an environment supportive of strong
straight line winds with embedded meso-vortices (brief
tornados) over northeast South Dakota and west central
Minnesota. Additionally, there is the potential for convection
moving into south central and southeast South Dakota to make it
as far north as the U.S. Highway 212 corridor (Watertown area
over toward Milbank and Ortonville) later tonight after 05Z,
merging with ongoing storms over this CWA. Tornado Watch 294
continues across the forecast area west of Brown/Spink Counties
until 05Z. Severe Thunderstorm Watch 298 is now in effect for
Brown/Spink Counties until 09Z Wednesday.

UPDATE Issued at 614 PM CDT Tue Jun 9 2026

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.DISCUSSION...
Issued at 212 PM CDT Tue Jun 9 2026

The main forecast highlight today continues to be the potential for
strong to severe thunderstorms developing this afternoon and
continuing through this evening and overnight. A negatively tilted
trough over the western CONUS develops a low pressure center over
North Dakota/southern Canada, leading to a cold front moving across
the region this evening, ahead of which storms are expected to
develop today. As for storm mode and timing, current expectations
are that individual cells will form over western/central South
Dakota before coalescing into a line as the storms pass the Missouri
River and continue east.

With the initial development and assuming storms remain discrete as
they enter the Aberdeen CWA, hail will be a favorable threat. Strong
CAPE of 2000-3000 J/kg will be in place with the initial
development, and LCL-EL shear of 45+ knots and mid-level lapse rates
between 7-8 C/km will also support hail development, potentially
upwards of 2" at times. As storms progress east and morph into a
QLCS, the primary threat will shift to wind. DCAPE values well over
1000 J/kg will be in place, low-level lapse rates near the dry
adiabatic lapse rate will also offer easy access for gusts to mix to
the surface. 0-6km mean wind and EBWD both around 30-35 knots
further support the wind threat as well. With such a strong
environment for severe winds, we may see widespread significant wind
gusts (75+ mph) through the evening and into the early overnight
period.

As for the tornado threat, there appear to be a couple of things
working against the potential at this point, but can`t quite rule
things out. Currently, the best chances appear to be as the storms
coalesce into a line just east of the Missouri River. Hi-res model
guidance is pointing towards the idea that achieving 0-3km shear
will be somewhat difficult. LCLs out ahead of the front will also be
fairly high (>1000m) until around sunset, although there is a bit
more of a disagreement withing the models on this specific point.
All this to say that generally speaking, variables don`t seem to
quite line up well for the tornado threat, with the exception of the
Campbell/Walworth/McPherson/Edmunds County area. In that spot, shear
increases along the front, LCLs come down below 1000m, and low-level
helicity of 200-300 m2/s2 will be present. Therefore, wouldn`t be
surprised to see a spinup in that area in particular. The other
possible tornado scenario (albeit one that seems fairly unlikely) is
for a discrete supercell to develop out ahead of the front and main
line of convection this evening over northeastern South Dakota,
where if timed correctly (around 01-02Z) may be able to tap in to
some low-level shear. However, guidance gives very low confidence in
storms developing out ahead of the front, so there is limited
concern for this scenario at this time.

The Storm Prediction Center also has a Marginal Risk for severe
weather in place for far northeastern South Dakota and western
Minnesota for possible development Wednesday afternoon. At this
point there is still quite a degree of variability in location and
timing within the CAMs for Wednesday afternoon, but the one
consistent point seems to be that the strongest storms will develop
to the east of the Aberdeen forecast area, so limited concern for
severe development tomorrow.

Upper-level trough is expected to progress eastward through the end
of the week this week. The most prominent impact here will be height
falls across the region, leading to near-normal to slightly below
normal temperatures beginning Thursday. The replacement of the mT
airmass with a cP airmass will also push dew points in the 60s today
to the upper 40s by Thursday (roughly between the 25th and 50th
percentiles for this time of year). By next week model guidance
begins to diverge a bit on how the upper-level pattern will evolve,
but in general expect cold air advection aloft with some potential
for shortwaves to move through and develop some additional rainfall
chances.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 614 PM CDT Tue Jun 9 2026

Terminals KABR,KATY,KPIR,KMBG

Not sure if/when storms are going to develop over central South
Dakota, but guidance continues to indicate thunderstorm
potential at the KMBG and KPIR terminals generally between 01Z
and 03Z. Storm mode would be supercellular, with large hail and
damaging winds being the primary severe weather threats. An
isolated tornado concern is a lower probability secondary severe
weather threat. Beyond that, a cold front should be pushing into
the Missouri River valley signaling a wind shift and stabilizing
conditions and the end of any precipitation potential. Outside
of convection, VFR conditions are forecast to prevail through
the TAF valid period.

Guidance still indicates convection should develop over
western/central South Dakota over the next 2-3 hours and
increase in coverage as it moves off to the east-northeast. Once
it reaches northeast South Dakota (KABR/KATY), it could be
forming into a line of storms capable of rather strong/damaging
straight line winds. Presently still leaning on a window between
04Z and 07Z for this convective activity to role through the
KABR/KATY terminals. Beyond that, a cold front should be pushing into
the James and Big Sioux River valleys later tonight after 06Z,
signaling a wind shift and stabilizing conditions and the end of
any precipitation potential. Outside of convection, VFR
conditions are forecast to prevail through the TAF valid period.

&&

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

&&

$$

UPDATE...10
DISCUSSION...BC
AVIATION...10