421
FXUS63 KABR 151754 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1254 PM CDT Sun Jun 15 2025

.KEY MESSAGES...

- There is a Slight risk (2 out of 5) for severe thunderstorms
  across central and north central South Dakota mainly for
  thunderstorm potential later tonight. Main threat later tonight
  would be strong/damaging winds.

- There is an Enhanced risk (3 out of 5) for severe thunderstorms
  across far northeast South Dakota into west central Minnesota
  Monday afternoon. Large hail, damaging winds and a tornado or
  two are all possible severe weather threats Monday afternoon.

- Temperatures are forecast to warm to 5 to 10 degrees above
  normal by the end of the week.

&&

.UPDATE...
Issued at 1238 PM CDT Sun Jun 15 2025

Aviation discussion updated below for the 18Z TAFs.

UPDATE Issued at 1040 AM CDT Sun Jun 15 2025

Two MCV`s are tracking across the region this morning. The
northern one has pushed off into ND, while the southern one
continues to produce a complex of showers and thunderstorms across
Hand/Spink counties into portions of FSD`s CWA. There`s potential
for a few storms to become marginally severe, with hail around
quarter size, so will continue to monitor. Otherwise, once these
MCV`s move out of the area or dissipate, expecting mostly quiet
conditions through the remainder of the day and will await
overnight strong to severe storms as they roll into the central
Dakotas. Adjusted PoPs to better match radar trends, and the
anticipation of mostly quiet conditions post-MCV atmosphere. Also
dealing with an area of dense fog across parts of the eastern CWA,
mainly in the moist upslope region of the Coteau. Web cams over
there look rather socked in, so issued an SPS to cover this as
conditions should be improving somewhat over the next couple
hours. Plenty of clouds across the region still, but the look at
feel of the mean low cloud cover off HREF suggests perhaps an
earlier erosion to cloud cover compared to Saturday. Will likely
be adjusting sky cover grids quite a bit today. Hopefully high
temperatures are not too far off as cloud cover could ruin things.
Will remain somewhat optimistic that gradual cloud erosion and
increasing sunshine for some/many areas will still allow for highs
to reach the mid 70s and 80s across the CWA. But, some bust
potential today too for high temps.

&&

.DISCUSSION...
Issued at 401 AM CDT Sun Jun 15 2025

At 3 AM CDT, showers and thunderstorms are moving northeast through
the counties in the CWA that are west-river. There are two clusters
of thunderstorms of interest right now. The first is moving through
Dewey/Corson Counties while the second is down in Tripp County.
Adequate environmental characteristics; instability (600-800J/kg
hail CAPE), deep layer shear (30-40knots) and a decent outflow
boundary, accompanying a couple of mid-level shortwaves, are all
providing the potential for this early morning convection to reach
severe limits at times. This convection should continue to move off
to the northeast as the morning progresses. Short-term convective
guidance suggests more showers and storms may be able to develop
further east across the CWA between now and 18Z. PoPs are in the
forecast to account for this potential. Temperatures are running in
the 50s this morning on east-component winds around 5 to 15 mph.

Overall, the steering flow pattern through Sunday over the CONUS is
dominated by an upper level ridging pattern before upper level
longwave troffing develops late in the period. It`s a low amplitude
ridge pattern for the most part, with multiple smaller transient mid-
level shortwaves of low pressure progged to move west to east across
the region, the strongest of this impulses appearing to move through
on Tuesday/Tuesday night. The synoptic-scale pattern for the next
couple of days supports gulf moisture remaining in place over the
region, meaning surface dewpoints, at least, in the 60s over the CWA
and plenty of instability 2500+ J/kg CAPE at peak heating times
through Monday afternoon.

The SPC Day 1 outlook has the western third of the CWA currently in
a slight risk for severe weather (with an enhanced risk mainly for
wind) just west/northwest of the CWA. The next semi-discernible mid-
level shortwave appears to be heading for south central Montana at
this time. This system is expected to induce some strong convection
later this afternoon/evening out across the northern high plains
terrain of southern/southeastern Montana over into northeast
Wyoming. Over time, guidance appears to transition convective threat
from a supercell/large hail scenario to more of a MCS/strong and
damaging wind threat. And it is this wind threat that could be
running into the northwestern forecast zones later tonight (early
Monday morning) after midnight.

The SPC Day 2 outlook has the eastern and southern portions of the
CWA in a slight risk for severe weather, with an enhanced risk for
severe weather over the far eastern forecast zones. At this point,
severe weather guidance indicates that if convection were to develop
along a frontal boundary/within a surface trof draped over the
region, deep layer instability/shear would point storm mode to
supercellular. Low level severe parameters, at this time, also
support a conditional/localized tornado threat Monday afternoon
across the Prairie Coteau over into west central Minnesota.
Conditional because depending how influencing tonight/early Monday`s
convective event is, the cold front may be blown well south/east of
the CWA by Monday afternoon. Something to watch for heading into
Monday. The system that moves through on Monday has a cold front
attached to it, which is progged to scour out some of this higher
moisture content air for, at least a couple of days while surface
high pressure extends its influence down into the region. By
Thursday night, though, return flow appears to set back up, and
persist heading into the weekend.

Low level thermal progs do show a steady diet of warming conditions
underneath this ridge aloft. Although, as the past few days have
confirmed, a lot will depend on how long it takes to scour out the
fog/low clouds. That said, the fog/low clouds should become less and
less of temperature forecast factor over the next day or two with
daytime mixing/heating. Later in the period, low level thermal progs
and ensemble S.A. table temperature anomalies do indicate that some
fairly toasty temperatures are on the way for the end of the week,
into the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1238 PM CDT Sun Jun 15 2025

Terminals KABR,KATY,KPIR,KMBG

MVFR/IFR (mostly MVFR) CIGs continue to affect KABR/KATY this
morning. Low confidence on when/if these clouds dissipate today,
but forecast to try to do so by late afternoon. TSRA/SHRA also
will affect KATY at the start of the TAF period, with MVFR/IFR
VSBY possible. Across KPIR/KMBG, VFR conditions are forecast
through the daytime hours. Overnight into Monday morning,
TSRA/+TSRA are forecast to move into central SD and eventually
into the James River valley. Storms could be severe across central
SD (KPIR/KMBG) with surface wind gusts over 55 knots.

&&

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

$$

UPDATE...TMT
DISCUSSION...10
AVIATION...TMT