Mahto, South Dakota Weather Forecast Discussion

016
FXUS63 KABR 261547 AAB
AFDABR
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1047 AM CDT Fri Sep 26 2025
.KEY MESSAGES...
- Winds will be breezy Friday, both ahead of and behind a dry cold
front passage, with gusts of 20 to 30 mph in the afternoon and
evening.
- Sunday through Wednesday looks mild, dry and windy. Highs are
forecast in low to mid 80s (15 to 20 degrees above normal), with
south winds gusting up between 25-35 mph.
&&
.UPDATE...
Issued at 1031 AM CDT Fri Sep 26 2025
Valley fog across portions of the Missouri and Cheyenne River
valleys has burned off leaving clear skies. Mostly sunny skies and
warm temperatures are still expected today ahead of a cold front
that will shift into western SD this afternoon. Gusty winds ahead
of and behind this front is still anticipated later today into
tonight. The forecast for the remainder of today is on track with
no changes expected.
UPDATE Issued at 543 AM CDT Fri Sep 26 2025
Aviation discussion has been updated below in accordance with the
12Z TAF issuance.
&&
.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 313 AM CDT Fri Sep 26 2025
Broad upper-level ridge will continue to sit over the CONUS today,
leading to well above normal temperatures in the 80s across the
forecast area. A dry cold front is expected to pass Friday evening
into Saturday, leading to a brief cooldown. Highs in the low 70s
will be much closer to the climatological normal for the end of
September, and dew points will drop 10-15 degrees compared to pre-
frontal conditions, bottoming out in the 40s.
The main impacts in the short-term forecast are gusty winds, both
pre- and post-frontal. Headlines are not expected at this time and
both sustained winds and wind gusts will fall well short of advisory
criteria. Still, gusts will pick up to about 25 knots today out of
the southwest. Along the front winds calm to between 10-15 knots
before picking back up to 20 gusting to 25 knots under the
northwesterly cold air advection regime. A surface high pressure
center will move in quickly after, dropping winds and shutting down
the near-surface cold air advection, thus allowing temperatures to
warm back up by Sunday.
&&
.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 313 AM CDT Fri Sep 26 2025
Departing upper level trough across the Canadian border will
briefly put us into a northwest flow regime for Saturday night,
which then shifts to more zonal west to east flow Sunday. A broad
ridge centered over the southeast CONUS gradually amplifies the
upstream pattern for early next week, with southerly to
southwesterly upper level flow Monday/Tuesday as an upper trough
develops across the western CONUS. This is essentially a dry pattern
for this time of year, as well as one that indicate a gradual
warming trend. Deterministic GFS/Canadian/EC 850mb temperatures
dictate as such, with the coolest readings in the wake up the upper
trough, at about +12 to +16C Saturday evening, increasing to a peak
of around +22C by Monday. The core of warmest air lifts northwards
but mild temperatures persist for Tuesday/Wednesday. The NBM follows
suit, with a steady warming trend that peaks Monday with
deterministic highs only about 2F `cooler` for mid-week.
That upper trough will take most of the rest of the week to come
onshore and start to progress through the intermountain west. As
such, POPs are expected to remain relatively low as a southwest flow
regime this time of year is less conducive for widespread convection
and the southwest monsoon has usually wrapped up. Now, there is a
tiny wrinkle, in that there is some moisture and convection across
the southwest now, and the upper low and moisture associated with
this activity will eject into the Northern Plains Tuesday. GFS
BUFKIT profiles depict moisture/moist adiabatic profiles above
12kft/600mb with a dry/mild subcloud layer. A couple of GEFS plumes
members even generate a few tenths of QPF.
With good agreement in general between deterministic models, NBM
temperatures show little range (3-4 degrees) in the 25th/75th
percentiles for highs/lows during the first half of next week,
meaning a high confidence forecast, and is running about 15 to 20
degrees above average for highs and 20 to 25 degrees above normal
for lows. There is an increasing trend for QPF late week, but that
is still days 6-7. As for winds, the gradient is strongest on the
backside of the high Sunday/Monday/Tuesday timeframe with southerly
return flow, and not expected to weaken/shift east until about
Wednesday/Thursday. As vegetation continues to dry out, we may
develop a period of fire weather concerns, though with how wet we
were a week ago there is a degree of uncertainty as to how impactful
this period of mild and windy conditions will be.
&&
.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 543 AM CDT Fri Sep 26 2025
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are expected through the TAF period. Strong wind
gusts up to 30 miles per hour are expected this afternoon through
tonight, both ahead of and behind the passage of a dry cold front
today. With the passage of the front, winds will veer from out of
the south to be out of the northwest. There is also a chance for
some low-level wind shear over northeastern South Dakota tonight
with a 30 to 40 knot low-level jet, but will quickly pass and be out
of the area by Saturday morning. Currently only have the wind shear
in the KATY TAF, as coverage of the jet is not expected to impact
areas along or west of the James Valley.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Vipond
SHORT TERM...BC
LONG TERM...07
AVIATION...BC

NWS ABR Office Area Forecast Discussion