Sisseton, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

611
FXUS63 KABR 130524 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1224 AM CDT Fri Jun 13 2025

.KEY MESSAGES...

- There is a slight risk (2 out of 5) for severe thunderstorms
  over portions of south central South Dakota through this evening
  with a marginal risk (1 out of 5) for severe thunderstorms
  along and south of a line from Eagle Butte to Milbank.

- Showers and thunderstorms expected through Friday morning, with
  the highest chances (60-90%) of precipitation along and east of
  the Sisseton Hills. An additional 1 to 2 inches of rain is
  forecast, highest over far northeastern SD into west central MN
  through Friday morning.

- Elevated smoke remains over the region with an intermittent
  return of near surface smoke and visibility reductions through
  Friday.

&&

.UPDATE...
Issued at 1220 AM CDT Fri Jun 13 2025

Update for 06Z TAF discussion below.

UPDATE Issued at 627 PM CDT Thu Jun 12 2025

Strong to near severe storms remain from Spink/Clark County and
Lyman County early this evening. The bulk of the precipitation is
now east of a line from Eureka and Faulkton. We`ll continue to
monitor the latest trends for strong winds around 45 mph or
greater and small hail.

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 256 PM CDT Thu Jun 12 2025

As of 2PM, scattered showers and thunderstorms are mainly east
of the Missouri River, with the bulk of the precip along and east of
the Coteau. Satellite indicates cumulus cloud streets (a couple are
agitated) pushing northward, just to the south of the CWA. Skies in
this area are overall clear here so this should help destabilize the
atmosphere even more to help these cumulus clouds grow more
vertically. Temps are in the upper 50s to the mid 70s, warmest over
south central SD. Zonal flow aloft as the shortwave overhead
continues to flatten out over the Northern Plains with another weak
embedded shortwave moving west to east over ND overnight. The 700mb
low continues to spin over north central MT this afternoon and
evening, shifting over northeastern MT/northwestern ND/Canada border
through the overnight. The warm front/inverted surface trough will
continue to lift northward through the evening and sprawled across
our southern to southeastern CWA as the surface low will be centered
over southern SD/Nebraska border by 00Z. The system will track east,
then northeast (along with its 700mb low) through the overnight. By
12Z the low looks to be centered over east/southeastern SD/MN border
with its cold front draped southwest of the low through NE.

As of 19Z, along and just north of this warm front dewpoints are
already in the mid to upper 60s which is providing that low level
moisture. Instability wise, MLCAPE is already between 1000-1500j/kg
and SB/MU CAPE is running up to 2000j/kg or so, with the highest
values from Jones through Buffalo counties. 1000-2500 j/kg CAPE is
forecasted to continue, per HREF, through about 06Z before this
instability diminishes. There is a sharp cutoff in CAPE the further
north you go in the CWA where the further you get away the front,
the less instability. RAP is a little more aggressive on this
instability with values of 2000 to 3000 j/kg possible (highest over
Buffalo), which may not be out of the question with what we are
already seeing over south central SD. Mid level lapse rates are
running between 6.5-7.5, highest over central SD and shear running
between 40-50kts. 0-3km SRH looks to run between 200-400m2s3 and
around 100-150m2s2 for 0-1km SRH which is a bit higher than RAP.

So looking at the parameters, everything looks like it could be a
slam dunk for severe weather over our southern CWA, however, even
though the models (CAMS/HREF) do show redevelopment of convection in
this area the more the cap breaks, they are struggling to output
more numerous or even more widespread storms. The reason? Lack of
strong low level convergence (and weak winds) near and along the
front at 925mb with the better convergence to our south. This is
seen by the HREF as probability of HREF of 2-5km UH>72m2s2 is
10-30%, with the highest confidence over our far southern counties
as a few paintballs show this possibility in this area.
Probability of UH>150m2s2 is 10% over our southern counties (and
only 1 or 2 members show this). STP over the southern half of the
CWA runs between 0.5 and 1, highest over Buffalo, Hand, and Hyde
counties. RAP hodographs do show this low level curvature. So if
we get a supercell or two to form (looks to be more low-topped
nature) the conditions are favoriable for a possible tornado or
two developing. Main threat will be hail, up to a quarter, to
maybe a bit larger if supercells form along with wind gusts
between 60-70 mph (on the higher end if we get more outflow
dominant storms).

There is also the threat of heavy rain per WAA side of this 700mb
low over MT and along and north of the 700mb low that will be over
eastern SD/western MN with this southern system. RAP 1000-500mb RH
shows this well as the 90%+ RH stretches from MCPherson/Edmunds and
eastward through the Coteau into west central MN this afternoon and
tonight, pushing northeastward out of the CWA by early Friday
morning. PWAT values east of the Mo River will run from a inch to
1.25" through the evening, shifting along and east of the Coteau
overnight and into MN by 12Z Friday. This looks to run about 1 or so
standard deviation above climo. EC EFI still has values of 0.5 to
0.6 with these values shifted way north than the past previous days
which matches the area where this WAA/strongest lift will be for
heavier rain. Additional QPF from 00Z Friday to 00Z Saturday is 1-
2", highest from Roberts County into west central MN.

High pressure to our north will keep much of the area dry for Friday
(with the exception of along the Coteau and east) as lingering
showers are possible around and on the backside3 of this low with
pops of 30-50%. Additional chances for precip are possible on
Saturday.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 256 PM CDT Thu Jun 12 2025

Saturday: A ridge aloft initially, with a wave in southwest Canada.
Heights are increasing, as a 4-corners high is beginning to develop.
We can see very subtle waves aloft embedded within this southwest
flow topping the ridge, one depicted during the daytime hours on the
ND/SD state line, followed by another later Saturday in Wyoming.
There are some traces of a plume of moisture across the
intermountain west associated with these features, and we`re seeing
mid-level warm advection overhead during the day. This would suggest
steepening lapse rates aloft which is confirmed in the NAM/GFS
BUFKIT soundings. Low level flow is easterly with a inversion and
CAP to potentially overcome for surface based convection - and
elevated convection seems the more probable outcome with these
systems, especially as we get into the overnight hours and flow
becomes more zonal.

Sunday: Morning convection continues to move east southeast. The
Canadian wave, now in Saskatchewan continues east to suppress the
ridge with a more broad ridge and zonal flow overhead. May be an
additional subtle wave aloft, but not conclusively between
deterministic guidance. 700mb temperatures are still above +10C, so
with suspect upper level support, surface based convection may
remain surpressed/capped.  During the overnight hours, another subtle
southwest flow shortwave ejects out of Wyoming which would support
additional chances for elevated convection. The 4-corners high
weakens, as a trough moves into the western CONUS.

Monday/Tuesday: A messy parade of weak shortwave moves into the
northern Rockies, suppressing the ridge overhead. The strongest of
these waves comes in late Tuesday. 700mb temperatures remain above
+10C for the most part, so we will continue to deal with elevated
convection. SPC is highlighting the Tuesday wave as the one that
would present us with the best chance for organized severe weather,
thanks to stronger flow aloft, however given timescales and low
consistency between run to run and among different deterministic
models, confidence is not high. CWASP subsequently peaks on Tuesday,
in addition to GEFS plumes CAPE. Machine learning/AI are more
broadly highlighting western SD/southeast SD with lower
probabilities across central/north central/northeast SD during this
timeperiod.

Wednesday/Thursday/Friday: With the departure of the wave, this will
give us short amount of time to dry out as the pattern quickly
returns to zonal with additional weak waves progressing west to east
across the northern Rockies. Thus, we will continue the low
probabilities for moisture through the later half of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1220 AM CDT Fri Jun 13 2025

Terminals KABR,KATY,KPIR,KMBG

The frequent rain showers of Thursday will continue to slowly
diminish, with little to no additional ran expected at PIR/MBG.
However, there will be at least some nearby showers at ABR/ATY
through 12Z Friday. The significant low level moisture will help
keep some reduction in visibility of at least MVFR category at ATY
through the TAF period. MVFR to IFR ceilings are also anticipated
through much of the time. PIR has the highest chance of returning
to VFR conditions by around 00Z Saturday.

&&

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

$$

UPDATE...13
SHORT TERM...MMM
LONG TERM...07
AVIATION...13