780
FXUS63 KABR 210605
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
105 AM CDT Sun Jun 21 2026

.KEY MESSAGES...

- Rain today across central South Dakota. Probability of
  exceeding 2" up to 60% across Jones/Lyman counties. Potential
  rainfall amounts drop off dramatically north and east with
  little if any expected for northeast SD/western MN.

- A fast moving system Monday night/Tuesday morning with a
  40-70% chance of > 0.25". Severe weather is not anticipated.

- Temperatures remain near to slightly below normal through next
  week. Coolest day being today at 5 to 20 degrees below normal.
  More seasonal temps and humidity late week/next weekend.

&&

.DISCUSSION...
Issued at 101 AM CDT Sun Jun 21 2026

Not much overall change with the system today, with main placement
of the QPF bullseye still over central South Dakota. HREF/NBM have a
peak 2+" along the I90 corridor in central/south central South
Dakota, with a gradient to the northeast and less than a 1/4" for
Aberdeen/Watertown. That said, deterministic forecast is a little
lower at 1 to 1.5" though same bullseye placement lending continued
high confidence in regards to drought relief across central South
Dakota. To the north, Mobridge area, looking at a drop in the
deterministic forecast down to about 0.1" which is close to the HREF
mean and well below the deterministic NBM which still sits just above
1/2". Thus, a little uncertain across the north central with a
gradient from north to south. Same thing as we transition into
northeast South Dakota, with a gradient that continues to drop off
to near nothing by the time you get to Aberdeen/Watertown as
mentioned earlier.

Looking to the next wave that follows close behind. Still looking at
a rapid frontal progression during the overnight hours
Monday/Tuesday morning which will limit rainfall amounts. Mean NBM
is a tenth or two, with our deterministic forecast running just a tad
higher. NAM BUFKIT profiles depict skinny CAPE on the order of 100-
200j/kg and limited shear below 400mb.

Thereafter we remain in a west to northwest flow regime. While not
much low level moisture, mid level cool air will result in daytime
driven destabilization with the NAM showing some CAPE under a
unidirectional shear environment, not unlike the last couple of days
of convective activity.  NBM lingers POPs across the far east
Tuesday afternoon. Likely a similar situation for Wednesday
afternoon though more northerly flow as the surface high shifts
to to the eastern Dakotas/western Minnesota. Return flow on the
backside of the high takes over for late Thursday/Friday. Mid
level warm advection aided convection shows up in NBM POPs
Friday morning.

Looking way way out, late weekend/early next week we see a trough
set up over the Northern Rockies. Now established southerly flow
across the Plains taps into Gulf moisture which has been pooling in
the souther/central Plains. We`re starting to see NBM reflect this
in 60+ dewpoints. The trajectory of the system is still to be
resolved given how far out, but it should be noted that there is
fairly good agreement in deterministic models at this point. It also
should be noted that this storm trajectory has the potential to draw
in some very warm air aloft. The GFS has +17C at 700mb, though the
GEFS mean at this point is only +10C and barely registers as a
standard deviation above climo. This GEFS mean is underdone this
far out given the spread in ensemble outcomes but is telling in that
at a minimum when this system progresses though a 700mb temperature
cap will need to be reckoned with when assessing any severe
weather potential.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1230 AM CDT Sun Jun 21 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected for a majority of the time period.
The highest chance of steady rain/showers will be over PIR,
where MVFR to IFR ceilings will be possible from 08Z this
morning through the remainder of the daytime hours. Farther
north and east, expect VFR conditions to continue. While
thunderstorms will be possible, the coverage/confidence is less
than 30% at this point at PIR. Little to no precipitation is
expected at ABR/ATY, with more off and on showers at MBG through
the daytime hours today.

&&

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

&&

$$

DISCUSSION...07
AVIATION...06