012
FXUS63 KABR 310737
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
237 AM CDT Sun May 31 2026

.KEY MESSAGES...

- Active pattern continues, and chances for showers and
thunderstorms are in place through at least mid-week.

- Probability of additional rainfall of half an inch or greater
through Monday is roughly 30-50% over northeastern South Dakota and
western Minnesota, increasing to around 60-80% over central and
north central South Dakota.

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

- Another Marginal Risk (Level 1 of 5) is in effect for Monday for
parts of northeastern South Dakota. Wind gusts of 60 mph and hail up
to an inch in diameter are the main potential threats.

&&

.DISCUSSION...
Issued at 236 AM CDT Sun May 31 2026

Currently (~06Z) keeping a close eye on a line of storms moving into
central South Dakota early this morning. Over the past hour, surface
observations indicate that win gusts are consistently in the 40-50
miles per hour range, with some stray gusts upwards of 50 (remaining
sub-severe for the moment). Expectations over the next couple of
hours based on hi-res models are that storms will continue moving
into north central South Dakota, gradually deteriorating as they go.
Mesoanalysis seems to agree with this assessment based on the idea
that shear will decrease moving north. There is still some decent
DCAPE (topping out around 900 J/kg) over parts of north central
South Dakota that storms are expected to move into over the next
couple of hours, so until storms dissipate, an isolated severe gust
may still be possible.

Attention then turns to this evening`s severe threat, with currently
a Marginal Risk for severe storms in place. Storms are expected to
take the form of more individual cells, with the best chances for
the severe threat located along the James River Valley. A plume of
roughly 1500-2000 J/kg of MUCAPE will be in place, and mid-level
lapse rates around 7 C/km will also help to support the hail threat.
Shear may be a bit of a struggle, but still expecting around 20-30
knots of 0-6km shear lining up with the plume of CAPE (albeit with
some local variability). Therefore, can`t rule out the potential for
severe hail in the areas of strongest shear. Conversely, areas of
weaker shear will likely hold the strongest wind threat, mainly due
to the potential for collapsing storms. However other than some
marginal DCAPE in the 750-1000 J/kg range, not much in the
environment points towards the severe wind threat. Low-level lapse
rates will be fairly poor (6-7 C/km) and PWATs fall a bit short of
the ideal 1.5" for microbursts. That said collapsing storms may be
able to produce a stray gust or two, hence the greater potential on
the weaker end of the shear. In terms of the potential tornado
threat, generally expecting the area of best shear/helicity to be
disconnected from the lowest LCLs until later in the evening (as
well as fairly low 0-1km shear where storms are present, struggling
to get up to 20 knots). The area where all the ingredients could
potentially line up appears to be over parts of central South Dakota
around sunset and/or over far northeastern South Dakota. However,
there is not great consistency between model guidance at this point,
so confidence on both the existence and location of possible
tornadoes remains quite low.

In terms of rainfall totals still to come, the highest rainfall
totals are still expected over central and north central South
Dakota. The majority of remaining rain is expected with this
morning`s convection moving in currently, but scattered showers this
evening may also dump an additional quarter to half an inch (though
totals will be highly locally varied). Probability to see another
half an inch through Monday sits around 30-50% over northeastern
South Dakota and western Minnesota, increasing to 60-80% over
central and north central South Dakota.

Through the start of the work week, the upper-level low over the
western CONUS will continue to bring chances for rain, with perhaps
a bit of a break Monday afternoon and evening. The Storm Prediction
Center has drawn a Marginal Risk up into parts of northeastern South
Dakota Monday, and there does appear to be some CAPE/shear
combination in the area during the evening time frame. However,
confidence remains quite low due to very few models actually
displaying convective initiation, and those that do keeping showers
very weak. Both Tuesday and Wednesday evenings show perhaps some
better potential for some alignment between CAPE and shear within
the Aberdeen forecast area, and severe storms may be possible during
those periods. Flow aloft will transition to more zonal by mid to
late week. Beyond that point, there is fairly strong consensus in
the ensembles in another trough developing over the western CONUS
and potentially renewing the rain chances and severe potential for
the end of the week to the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1227 AM CDT Sun May 31 2026

Terminals KABR,KATY,KPIR,KMBG

A mix of VFR and MVFR conditions will prevail throughout the TAF
valid period. Within thunderstorms, expect visibility to fall
into IFR, temporarily. During the day on Sunday, conditions may
gradually return to VFR with daytime heating/mixing.

At the opening of this TAF valid period, strong thunderstorms
are moving through the KPIR terminal. Small hail (generally less
than 0.75in in diameter) and thunderstorm wind gusts up to 45
knots along with heavy rain is expected. Behind the leading line
of storms, a larger area of stratiform rain is expected for a
few hours. These conditions are forecast to spread up to the
KMBG terminal by 09Z. Meanwhile, more light rain showers with
embedded thunder are developing out near the KATY terminal.
During the 24 hour valid period, all four terminals should
experience, at least, a couple of hours of precipitation chance.
By late Sunday afternoon, isolated to scattered strong
thunderstorms may be developing at or near the KMBG, KABR and
KATY terminals.

&&

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

&&

$$

DISCUSSION...BC
AVIATION...10