Sisseton, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

940
FXUS63 KABR 111715 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1215 PM CDT Fri Apr 11 2025

.KEY MESSAGES...

- High to very high Grassland Fire Danger Index values for today
along and west of the James River Valley with low afternoon humidity
and south winds with gusts of 20 to 25 mph.

-High to very high Grassland Fire Danger Saturday through Monday.

- High temperatures in the upper 60s to mid 70s Saturday will be 15
to 20 degrees above normal for this time of year.

- On Monday, strong winds out of the northwest will gust 35 to
around 45 mph.

&&

.UPDATE...
Issued at 1009 AM CDT Fri Apr 11 2025

Fog is quickly dissipating this morning, so allowed the dense fog
advisory to expire. Low spots along the Coteau may still have
visibility reduced to 1 to 4 miles for the next hour.

&&

.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 431 AM CDT Fri Apr 11 2025

Currently there is fog developing over the James River Valley and
the Prairie Coteau, with visibilities dropping down around a half to
a quarter mile. Because of this, a dense fog advisory has been issued
for areas east of HWY 281 through 10am CDT when the fog will start
to mix out.

Models look to have an upper-level ridge moving in during the day
today, and mainly stays over SD through the day Saturday. The mid-
levels have warm, dry air moving in during the day Friday. This dry
air leads to elevated fire weather concerns Friday afternoon as RH
values fall into the teens and low 20s. However, winds and gusts
look more marginal today than previous days, staying below 25 mph.
If winds start to increase and gust get above 25 mph for an extended
amount of time, a red flag warning might be needed during the
afternoon, and this is something the day shift can deliberate
further. This will lead to high grassland fire danger index west of
the James River today. Relative humidity will recover slightly
Saturday, staying in the mid 20s to mid 30s. This will lead to a
decrease in the grassland fire danger index Saturday.

Temperatures during the day today look to warm to the mid-70s west
of the Missouri River and mid-60s to low 70s to the east of the
river. Once the sun sets, temperatures will start cool, though some
clouds overnight will help to keep the temperatures from cooling
past the mid-40s.

&&

.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 431 AM CDT Fri Apr 11 2025

When the period opens Saturday night, an upper level low is
approaching the region, allowing for a period of southwest flow
aloft. Sunday night into Monday that upper low has tracked across
the region, mainly north of this CWA, with northwest flow aloft
taking over, persisting to the end of the period. Depending on how
models resolve a late period upper wave riding down the backside of
a western CONUS upper level ridge in place, there may be some
precipitation chances developing over the region from early Thursday
morning through Thursday night.

The initial upper level low approaching Saturday night may be
dragging some precipitation chances (showers; maybe a thunderstorm
or two) into portions of north central South Dakota. Storm
motion/upper steering flow would take the majority of any
precipitation chances northeast into North Dakota. There is a 30-60
percent chance that portions of north central South Dakota could see
a tenth of an inch or more of rainfall between 7 pm CDT Saturday and
7 pm CDT Sunday. In this upper system`s wake on Monday, will have to
see if any diabatically-driven showers are possible. Otherwise, most
of the rest of period looks dry while this western CONUS upper
level ridge is building, except when that one last shortwave trof
may be riding down the back of this expanding upper ridge late
Wednesday night into Thursday. Guidance does not have much to say
about precipitation chances with that precipitation potential just
now.

With the pattern becoming one of low level CAA in the wake of the
early period upper low, temperatures appear to be trending downward
Sunday (mainly 60s) and Monday (mainly 50s), before a rebound in low
level warmth sets back up. Temperatures Wednesday and Thursday are
expected to be back into the mid 60s to mid 70s.

As for fire weather concerns, Sunday and Monday do look like windy
(northwest 20 to 30+mph with stronger gusts) days, but minimum
relative humidity values aren`t into criteria (~25 to 45 percent RH,
at worst). Meanwhile, when RH`s are at their worst (on Tuesday) in
the 15 to 25 percent range over the western forecast zones, wind
speeds do not look strong at all.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1214 PM CDT Fri Apr 11 2025

Terminals KABR,KATY,KPIR,KMBG

Breezy southerly winds develop today and continue through tonight
before diminishing Saturday morning. VFR conditions are expected
through the next 24 hours.

&&

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

$$

UPDATE...20
SHORT TERM...12
LONG TERM...10
AVIATION...20