137
FXUS63 KABR 301934
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
234 PM CDT Sat May 30 2026

.KEY MESSAGES...

- The Northern Plains will see an active pattern, and chances for
showers and thunderstorms are in place through the rest of the
weekend and into the start of next week.

- Probability of rain amounts of a quarter of an inch or more
through Sunday evening is 60 to 90% west of the James River, highest
along and west of the Missouri River.

- A Marginal Risk (level 1 of 5) for severe weather is in effect
along and west of a line from McIntosh to Miller late late this
evening through tonight. Damaging wind gusts of 60-70 mph and hail
up to one inch in diameter are the main threats. Brief heavy
downpours are also possible.

- There is a Marginal Risk (Level 1 of 5) for all of central and
portions of northeastern SD Sunday afternoon and evening. Main
threats include wind gusts of 60 mph and hail up to an inch in
diameter.

&&

.DISCUSSION...
Issued at 233 PM CDT Sat May 30 2026

Main concern will be the threat of severe weather over central SD
late tonight and again Sunday afternoon/evening for north central,
central, and portions of northeastern SD. Water Vapor imagery
indicates a small mid-level circulation within an overall negative
shortwave right over the CWA (which lies northeast of the closed
low). This setup along with ongoing southeasterly flow/increased low
moisture and daytime heating, scattered showers and a few
thunderstorms will continue to form and track north/northwestward
here and there for the rest of the afternoon into the evening. CAMs
show this well, however, exact coverage and location of this
convection do differ from each other. NBM does a good job blending
these outcomes. CAPE values during this time will increase between
1000-2000 j/kg mainly over central SD with the highest over south
central SD and mid level lapse rates of 6-7C/km. However, shear will
be lacking at this time keeping the threat for any bowing/QLCS setup
low. The majority of the storms through early evening look to stay
north and east of this instability so severe weather is not
anticipated at this time, however, if we do get some discrete cells
forming earlier over south central SD then some could produce
quarter size hail/wind gusts of 60mph.

Our attention then turns to late this evening through the overnight.
The cutoff low will continue to track northward and over WY by 00Z
(and its 850mb low over MT) with a stronger embedded negative tilted
shortwave to the southeast of the center of the low over CO/NE/KS.
At the surface, an elongated area of low pressure with several
embedded circulations reside along the leeside of the Rockies. One
circulation will be over WY/SD and its occluded front extending
southward with a stronger low over CO/KS/NE border. This energy
aloft and along and east of the surface boundary will be the focus
of storms firing up over eastern WY and western SD/NE into KS late
this afternoon and evening once the cap breaks in the form of
discrete cells/clusters per CAMs. CAMs then show this convection
coming together and transitioning into more of a line or broken line
of storms as they grow upscale and tracking northeast (northern
portion of line looks to track north) over central SD between ~03-
06Z. Once east of the Missouri River, the convection looks to really
fall apart and weaken due to lack of instability.

Speaking of instability, CAPE values will still run between 1000-
2000 j/kg over central SD with the highest clipping Jones County as
most of the this higher CAPE will lie west and south of the CWA.
Values really diminish the furthest east you go in SD. Once the
line of storms go through, this kills off the higher CAPE with
values below 1000 j/kg. No real bulk shear ahead of the potential
convection, however, it does increase behind it to 30kts over
portions of central SD for a few hours, within the wake of the
storms. HREF still highlights the potential for a few discrete
organized cells/clusters along and west of the Mo RIver, per
UH>75m2s2, either ahead of within the developing line before 06Z,
but falling apart as the convection tracks east as mentioned. The
SPC has pushed any severe just ever so slightly southeast. There is
still a Marginal risk for severe storms (1/5) along and west of a
line from McIntosh to Miller with a slight risk (2/5) now only
clipping far southwestern Jones County. Main threat will be wind
gusts of 60 to potentially 70 mph if the system becomes organized as
DCAPE will be over 1000 j/kg over central SD. Otherwise, quarter
size hail and brief heavy downpours will be the other threats.

For Sunday, this negative tilted wave will be over SD and upper low
still over WY/MT in the morning. This surface low will still be over
northwestern SD and occluded front/trough stretching through
southern SD in the morning. This low will track southward and along
the SD/NE border by 00Z and to the north of this low, a surface
trough sets up through central SD and northeastward to the northern
circulation now over southern Saskatchewan. Similar severe
parameters expected Sunday afternoon and evening except CAPE of 1-2K
will be east of the Mo River and 700-500mb lapse rates of 6-7C/km.
So upper level low`s energy and surface trough will bring the
potential once again for ongoing scattered showers and thunderstorms
that could become severe in the afternoon and evening per daytime
heating. The SPC has a Marginal risk (level 1/5) over much of the
CWA with the exception of far northeastern SD/western MN. Main
threats include quarter size hail and winds up to 60 mph.

Probability of rain amounts of a quarter of an inch or more through
Sunday evening is 60 to 90% west of the James River, highest along
and west of the Mo River. Prob of a half inch or more is 40-70% over
central SD. Otherwise this cutoff low over MT/Canada will continue
through early next week before tracking into Canada and becoming an
open wave by the middle of next week or so with a ridge off to our
east. This setup will bring continuing chances of scattered showers
and thunderstorms. CSU/NSSL machine learning does highlight the
potential of severe weather Tuesday-Thursday over the Northern
Plains, however, confidence on exact setup/details and location is
low at this time. Temps will continue in the 70s/80s through the
weekend and much of next week which is about average for this time
of year.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1215 PM CDT Sat May 30 2026

Terminals KABR,KATY,KPIR,KMBG

Scattered rain showers (and an occasional thunderstorm) will
continue here and there across the region with the threat of
thunderstorms over KPIR and possibly KMBG as a broken line or
clusters of storms will track northeastward out of WY/NE and
over central SD between ~03-06Z Sunday. Hail up to the size of
quarters and wind gusts of 60 to potentially 70 mph are possible
with any stronger storms over this location during this time.
Any brief heavy downpours will result in temporary cig
reductions as well. Storms are expected to weaken in strength
east of the Missouri River through early Sunday morning. Mainly
VFR/MVFR cigs are forecast through the TAF period with lower
cloud deck moving in late Sunday morning (~14-16Z) resulting in
a drop to IFR cigs possible. Winds will remain breezy out of the
south and southeast with gusts to 25-30kts.

&&

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

&&

$$

DISCUSSION...MMM
AVIATION...MMM