427
FXUS63 KABR 141921
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
221 PM CDT Mon Sep 14 2026

.KEY MESSAGES...

- Strong west to northwesterly winds will increase behind a cold
front this afternoon and continue through the overnight hours. Wind
gusts will range between 30 to 55 mph, with the highest gusts across
north central SD (Wind Advisory remains in effect) and along the
eastern slopes of the Sisseton Hills through Tuesday morning.

- Dry conditions expected for Tuesday before weak disturbances are
forecast to track over the region Wednesday through the weekend
bringing the opportunity for occasional showers and thunderstorms.

&&

.DISCUSSION...
Issued at 220 PM CDT Mon Sep 14 2026

As of 19Z, the center of the stacked low pressure system is over
northwestern ND/MT/Canadian border with the occluded/cold front
extending southward through central SD (right along the Mo River)
with winds west of the Mo River out of the west behind it. Temps
range in the upper 50s and 60s with dewpoints in the 60s. So far,
rain amounts at the office have been just below an inch for the day.
Radar continues to show scattered showers and weak thunderstorms
continuing east of the James River with an area of light showers or
drizzle over portions of north central SD. Low stratus clouds
continue (IFR/MVFR) with ceilings from 900-1500ft. As the front
continues to track eastward, the last of the precip will exit
eastern SD/MN by 00Z with skies clearing west to east across the
CWA.

Through the evening, the low continues to deepen (to ~991mb) as it
tracks northeast into Canada with a secondary cold front/trough
tracking northwest to southeast over the CWA on the backside of the
low tonight through the overnight hours. As the low deepens and
pressure gradient tightens, the northeast to southwest jet streak
circling around the southern/backside side of the low over the
Northern Plains increases with winds at 500mb around 60-80kts, 850mb
winds 35-55kts, and 925mb winds 30-45kts. 6hr pressure rises by 00Z
per GFS is about +2 to +5mb over central SD, with these values
spreading eastward across the CWA by 06Z. We really see an increase
in pressure rises (up to +9mb, highest central SD) 06-12Z Tuesday as
high pressure begins to filter in. This coincides with strong CAA
moving in, especially with secondary trough, as models indicate 850mb
temps go from +14 to +16C at 00Z to +6 to +10 by 12Z and 925mb temps
from +19 to +23C to +10 to +13C. So a drop in 6-9 degrees drop in 12
hours! So pressure rises/steeper/gradients and CAA are ingredients
for stronger winds at the surface. However, RAP soundings do indicate
a shallow inversion developing this evening but seems to erode a bit
with the colder/drier air moving in overnight, especially over the
northern portions of SD. A stronger inversion does remain over south
central and farther east you go into the CWA. This should allow for
ongoing mixing to occur towards the surface.

So just behind the front, surface gusts this afternoon and evening
will be highest over central SD, particularly north central SD with
gusts of 30 to 55 mph. There may be a brief lull/decrease in winds
late this evening before the secondary boundary passes across the
CWA. Therefore, the combination of the increasing winds aloft,
stronger pressure rises, and CAA will steepen the lapse rates with
gusts between 25-45 mph, highest over northern and northeastern SD
through Tuesday morning. Probability of NBM wind gusts>45mph is 40-
70% over north central SD (highest Corson/Dewey to the Leola Hills)
with a 30-50% chance along the eastern slopes of the Coteau. 24 hour
max wind gust potential ranges from 40-60 mph, highest north central
SD. HREF probability of gusts at or over 45 mph is upwards of 40-70%
over north central SD and higher than NBM for Coteau ranging from 50-
75%. So blended NBM/NBM90 for winds downslope of the Coteau to
represent this potential higher gusts. So the Wind Advisory across
north central SD remains in effect through the overnight. If we end
up getting more widespread wind advisory winds, then it will need to
be expanded eastward. Also was hesitant on issuing a Wind Advisory
for the Coteau with a lack of southwest component and the deeper
inversion. This will also need to be monitored with the next shifts.
As mentioned, if we develop a stronger and/or larger inversion (or
less CAA) then the gustier winds will not mix down as effectively to
the surface.

By Tuesday, the low/trough aloft will be northeast of the CWA with
zonal flow as high pressure filters into the region with overall dry
weather expected. As the high moves in, pressure gradients relax and
the gustier winds aloft with the low move out of the area.
Therefore, winds will decrease through Tuesday. Zonal to southwest
flow continues Wednesday through the end of the week as a cutoff low
aloft and its trough hovers over the western CONUS (low weakens into
an open wave by Friday) with a ridge and mid level high
strengthening over the central and southeastern US. Within this
zonal to southwest flow in an active -PNA pattern, weak shortwaves
will pass over the region Wednesday through the weekend bringing
occasional chances of showers and thunderstorms with the best chance
(50-80%) being late Thursday and Friday. Temperatures will overall
be about normal ranging in upper 60s and 70s across the CWA through
the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1214 PM CDT Mon Sep 14 2026

Terminals KABR,KATY,KPIR,KMBG

Rain has ended at KPIR/KMBG with light to moderate rain continuing
at KABR/KATY as the back edge of the precip is just west of the
James River. As the front continues to track eastward, the last
of the rain should exit far eastern SD/MN by later this
afternoon to early this evening. MVFR/IFR cigs per low stratus
will decrease west to east behind the front through the late
afternoon and evening with ceilings increasing. VFR cigs are
then forecast through the rest of the TAF period.

Behind the front per colder air, pressure rises, and stronger
winds aloft will mix down with winds increasing west to east
across the region with gusts of 30 to 55 mph out of the
west/northwest this afternoon through early Tuesday morning.
High pressure will filter in, diminishing the winds through
Tuesday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 1 AM MDT Tuesday for SDZ003-015.
     Wind Advisory from 7 PM this evening to 4 AM CDT Tuesday for
     SDZ004-005-009-010.
MN...None.

&&

$$

DISCUSSION...MMM
AVIATION...MMM