Sisseton, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

690
FXUS63 KABR 041551 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1051 AM CDT Mon May 4 2026

.KEY MESSAGES...

- Winds out of the northwest will gust 30 to 40 mph today with locally
  higher gusts possible. Winds will diminish late this evening
  through tonight.

- Widely scattered rain showers or sprinkles are possible this
  morning through this afternoon with chances between 15 to 25
  percent, mainly west of the James River. Little to no
  accumulation is expected.

- High temperatures Tuesday and Wednesday will run around 10 to
  20 degrees below normal ranging in the mid 40s to the mid
  50s. Early morning lows Tuesday through Thursday will drop
  into the upper 20s to the lower 30s (10 to 15 degrees below
  normal).

&&

.UPDATE...
Issued at 1050 AM CDT Mon May 4 2026

Lowered high temperatures today a few degrees with overcast
skies and colder air filtering in with the upper trough. Even
the lower high of mid 50s across the north may be too ambitious
for a few locales.

&&

.DISCUSSION...
Issued at 110 AM CDT Mon May 4 2026

As of 1am, the low is currently located over western Ontario with
its cold front draped from northwestern MN through central North
Dakota. Its surface trough is just ahead of it with its axis
positioned northeast to southwest over the CWA. Winds are out of the
southwest between 10-25 mph, highest along the eastern slopes of the
Sisseton Hill per downslope effect. Highest gusts so far have been
between 30 to 35 mph for several locations along the east side of
the Coteau. Over the next several hours as this low tracks east
across Ontario, the fropa will track southeastward across the CWA
with winds turning northwesterly behind the front (and ending the
downsloping event). This is a pretty quick moving front as it is
forecast to exit our far southeastern CWA around or just a little
after 12Z and out of the state late morning.

The strongest CAA will be over north central SD, just behind the
front around 12Z, where winds are expected to increase through the
early morning and gradually increase over the rest of the CWA
through 18Z as weaker CAA will be widespread over the CWA by then.
Pressure rises during this time won`t be anything spectacular but up
to +6mb/6hr during this time. NAM/RAP soundings show steep low level
lapse rates up to between 800-700mb with the top of the mixed layer
momentum transfer between 25 to 35 kts over the CWA and even up to
the lower 40kts over north central SD by the afternoon when we reach
peak daytime mixing. Rap is the more aggressive model in showing
lapse rates to 650mb, but luckily winds aloft aren`t incredibly
strong. Still, went ahead and stuck with a blend of NBM/NBM90th with
gusts ranging from 30 to 40 mph from mid to late morning through the
afternoon. Winds should stay below advisory criteria as EFI
indicates values of only 0.5 to 0.7 for wind speed/gusts over north
central and northeastern SD along the ND border. Probability of wind
gusts>45 mph is 25-35% over Corson County and the Leola Hills with
NBM 24 hr max potential wind gusts up to 50 mph here. So locally
higher gusts to 45+ is possible mainly over higher elevations of
north central SD with widespread 45mph+ gusts not anticipated. Winds
will diminish this evening as pressure gradients relax and we lose
daytime mixing.

Cams show the potential for a horizontal line of post frontal showers
tracking southward and over the ND/SD border around 12Z, and
tracking east/southeastward. However, most of the CAMs do show them
fizzling out becoming widely scattered or very spotty. This is due
to lots of dry air near the surface so any rain would be very light
or sprinkles or virga. CAMs still show additional convective showers
forming over the CWA behind this by the early afternoon to the early
evening, with HRRR/HREF being less impressed. So overall pops this
morning through the afternoon is 15-25%, mainly west of the James
River and highest along and west of the Mo River. Again being high
based and dry air below (little bit of elevated CAPE) not much QPF
is expected. Any shower(or weak storm) or collapsing shower could
bring a burst of gusty winds to the surface, up to 50 mph or so.
However, no severe weather is anticipated. Probability of QPF>0.01
is only 20-40% along and west of the Mo River. Otherwise, the CWA
will be on the southeastern side (within the inverted ridge) of a
large high pressure system over far northwest Canada by 00Z Tuesday
and ongoing high pressure will keep the forecast overall dry Tuesday
through at least Thursday.

Highs for today will be cooler behind the front ranging in the mid
50 to the lower 60s, warmest over south central SD. We really see
the colder air move in starting tonight with overnight lows in the
upper 20s to the lower 30s. Highs will be 10-20 degrees below
average Tuesday and Wednesday, only in the mid 40s and 50s and lows
still ranging in the mid/upper 20s to the lower 30s as 700-850mb
temps will be 1 to 2 standard deviations below climo per NAEFs
during this time. Our coldest morning looks to be Wednesday morning
as record lows will be within 5 degrees. May need to blend in some
NBM25 for morning lows Tuesday/Wednesday. Otherwise, warmer air will
move in from the west, under a ridge, gradually warming temps back
up for the end of the week with highs for the weekend back in the
upper 60s and 70s.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 630 AM CDT Mon May 4 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue to persist at all terminals through
this forecast cycle. Northwest winds will increase by mid to
late morning and remain gusty through the end of the day. Peak
gusts are expected to range between 25-30 knots.

&&

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

&&

$$

UPDATE...20
DISCUSSION...MMM
AVIATION...Vipond