981
FXUS63 KABR 272000
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
300 PM CDT Fri Jun 27 2025

.KEY MESSAGES...

- The entire forecast area has been classified as SLIGHT RISK (2 of
5) for severe weather this afternoon/evening. Large hail (2-
3")/Winds (60-80mph) are the main threats, however we also have the
potential for tornadoes mainly between the Missouri and James
Rivers.

- SLIGHT RISK (2 of 5) again for Saturday, mainly east of a line
from Aberdeen to Pierre, with a large hail and wind threat.

&&

.DISCUSSION...
Issued at 259 PM CDT Fri Jun 27 2025

Initial round of what was supposed to be morning convection finally
dissipated this past hour. A flat cu field is developing across
Lyman and Jones county in the warm sector south of a weak warm front
stretching west to east near I-90. This front will push northward
this evening and is expected to be the focus point for the first
strong to severe round of storms after 22z. Any storms along the
front will be discrete cells with a lot of instability to work with.
Around 4000 J/kg MUCAPE, a 20 kt llj, lapse rates of 7 to 8, and 35
kts of shear will be enough to support supercells. There`s an STP of
1 to 2 on the RAP13, as well, right around Pierre, so expect all
threats to be possible with any storms tied to the warm front.

Farther north is more questionable initially. The nose of the theta-
e ridge is in south central ND. So, while supercells may form along
that and shift south into the moisture tongue, there`s not really a
forcing mechanism across northern SD. Lower LCL heights, an
increasing and expanding llj, and 30 kts of low level shear will
still be very supportive of supercell continuation from western
Brown county back to the Missouri River late in the evening between
3z and 6z.

The severe threat shifts east on Saturday as the sfc low pushes into
central SD. By 18z, a sfc trough will stretch northeast from I-90 to
Sisseton. Along with a shortwave trough in the evening to the
southwest, storms may form along the boundary.

Another concern today and tomorrow will be the potential for
additional flooding across northeast and east central SD as storms
move over already saturated soil and rivers/creeks at bankfull.
PWATS remain at 1 to 1.5.

An upper trough slides into the Dakotas late Sunday with cooler
temps and somewhat drier conditions under a sfc high. Can`t rule out
some instability showers on northwest flow, however, through Monday.
A building ridge on Tuesday will also usher in a drier mid level air
mass briefly before return flow reintroduces moisture on southerly
flow Tuesday evening.




&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1226 PM CDT Fri Jun 27 2025

Terminals KABR,KATY,KPIR,KMBG

Showers are tapering off west of the KABR. Expect them to
dissipate by 19z. KATY will break out of the stratus around 19z as
well. The possibility of thunderstorms this evening is not so
clear cut. Weak forcing may keep most of the activity north (nose
of theta-e and weak trough/shortwave) and south (llj) of the
region. There is ample instability for storms to propagate if they
manage to fire off, though. Added prob30 groups for KABR and KATY
for now, but may need to clarify KMBG and KPIR as we near 0z.


&&

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

$$

DISCUSSION...20
AVIATION...20