198
FXUS63 KABR 021521 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1021 AM CDT Tue Jun 2 2026

.KEY MESSAGES...

- There is a Slight Risk (Level 2 of 5) for severe weather this
  evening, mainly along and west of a line from Eureka to Murdo.
  There is a Marginal Risk (Level 1 out of 5) for severe storms
  east of this line through the James River Valley. Large hail
  of 1-2" in diameter and wind gusts of 60 mph are the main
  threats. Tornadoes cannot be ruled out, along with heavy rain
  that could lead to flash flooding.

- Another Slight Risk for severe weather is in place for storms
  Wednesday afternoon and evening over northeastern and parts of
  central and north central South Dakota and west central
  Minnesota. Large hail of 1-2" in diameter and wind gusts of
  60 mph are the main threats. Tornadoes will also be a threat
  in the evening. Areas west of the Missouri River are under a
  Marginal Risk.

- Thursday, yet another Slight Risk for severe weather is in
  effect along and south of US Highway 12. Areas to the north
  of US Highway 12 are under a Marginal Risk. Large hail of 1-2"
  in diameter will be the main threat, with wind gusts of 60
  mph and tornadoes possible as secondary threats.

&&

.UPDATE...
Issued at 1013 AM CDT Tue Jun 2 2026

Quiet conditions across the CWA as satellite indicates overall
clear skies with cirrus clouds. Anvil cirrus clouds are moving
in over north central SD as there are isolated to scattered
storms over western ND/SD along the cold front. Current temps
are already in the 70s and dewpoints in the upper 50s to the
upper 60s. Overall sunny skies will continue to help destabilize
the atmosphere through the afternoon and erode the cap. This
along with low level moisture, warm temps, and the cold front
to our west will break the cap and allow storms to move in/fire
up over central SD this evening. Other then updated pop grids,
the forecast remains on track.

UPDATE Issued at 635 AM CDT Tue Jun 2 2026

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.DISCUSSION...
Issued at 247 AM CDT Tue Jun 2 2026

Upper-level low continues to bring chances for showers, storms, and
severe weather to the Northern Plains this week, beginning this
evening. The focus for today`s severe weather potential is over
central and north central South Dakota (mainly along and west of the
Missouri River). There will be some chances for sub-severe showers
and storms earlier this afternoon and evening over parts of
northeastern South Dakota, but the main severe threat will arrive
around 01Z-03Z, moving in from the west. While the latest hi-res
ensemble guidance indicates that the best environment is off to the
west, there will still be plenty of CAPE and shear (~2000 J/kg and
30-40 knots respectively) to sustain storms as they move in. Hail is
the main threat, with the above ingredients as well as mid-level
lapse rates around 6.5-7 C/km all supportive of at least severe
hail, perhaps significant (2" in diameter) at times. Confidence on
the wind threat is a bit lower, with only some marginal DCAPE
(approaching 1000 J/kg) to play with as storms move in, and little
else favoring wind gusts beyond collapsing storms. Not very
enthusiastic about the tornado potential either at this point, as
the setup for such would be quite marginal. In particular, DCAPE
appears to be somewhat limited, and 0-3km shear may struggle to
reach up to 30 knots at times. Still, can`t quite rule anything
out along the line of storms, especially if storms remain
discrete moving into the area. However, model guidance is
trending more in the direction of a line of storms by the time
they enter the Aberdeen CWA. Regardless of storm mode, if any
tornadoes do develop, the most likely location will be over
north central South Dakota.

Wednesday`s severe threat times out more to the afternoon to evening
hours, with storms developing in the James River Valley and
continuing off to the east through the rest of the day. Once again
expecting hail to be the main threat, and conditions appear
favorable for significant hail development (2000-2500 J/kg of CAPE,
30-40 knots of shear, and mid-level lapse rates > 7 C/km) and
perhaps supercells as well. Severe wind gusts will be the secondary
threat, with northeastern South Dakota once again being the main
potential threat area. DCAPE over 1000 J/kg will be present, along
with near-surface lapse rates nearly dry adiabatic, supporting
easier mixing to the surface. Concern for tornadoes is a little bit
higher Wednesday than today, mainly later in the afternoon to the
early evening. It`s at that point at which low-level shear is
expected to increase above 20 knots and SRH up to around 150-200
m2/s2 over the area. Strong curvature in low-level hodographs also
indicate the potential threat.

Yet another outlook is in place Thursday evening, with the main
threat being over parts of central and north central South Dakota
west of the Missouri River. Strong CAPE will be present in that
area, and while early looks at shear profiles are a bit varied,
there is enough of a signal for 30-40+ knots of shear to be
confident in the severe hail threat, perhaps significant at times.
There is again some disagreement on the mid-level lapse rates, but
some pockets of up to 6-7 C/km will also be in place, favorable
conditions for hail growth. Less concerned about the wind threat at
this point, as model soundings do not appear favorable at this time.
However, can`t quite rule out a stray gust or two with some marginal
DCAPE over central South Dakota. There does appear to be an isolated
tornado threat late Thursday evening, based on favorable helicity,
strong low-level shear, and low-LCLs lining up. However, this threat
appears to be fairly localized, and at this time range guidance
struggles to find consensus on exactly where the tornado threat is
greatest. At this time, forecaster confidence in the potential
threat is greatest over central South Dakota, but there is still
plenty of time for this to shift and evolve with future forecasts.

A weak upper-level ridge builds overhead late Friday into Saturday,
temporarily cutting off precipitation chances for the weekend. This
break may not last long however, as ensemble confidence remains
fairly high on another upper-level trough developing over the
western CONUS by next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 635 AM CDT Tue Jun 2 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are currently forecast through the TAF period.
Shower and thunderstorm potential will increase across central
(KPIR) and north central (KMBG) South Dakota by early this
evening into the overnight hours, perhaps even extending as far
as to KABR late tonight. Some of the thunderstorms that pass
over/by KPIR/KMBG could be severe, including large hail and
damaging winds. Continuing prob30 groups for KPIR/KMBG, and have
introduced some stronger wind gusts into the Prob30 groups to
denote that severe weather/wind potential.

&&

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

&&

$$

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