491
FXUS63 KABR 140748
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
248 AM CDT Mon Sep 14 2026

.KEY MESSAGES...

- Widespread rain showers and weak thunderstorms move into the area
early this morning, continuing into the afternoon. The heaviest
precipitation is expected after sunrise over parts of eastern South
Dakota and western Minnesota, where some areas may see upwards of an
inch of precipitation through this evening. Elsewhere, expect around
half an inch of rain in total.

- Strong northwesterly winds will increase behind a cold front this
afternoon into evening. Wind gusts will range between 40 to 55 miles
per hour this afternoon through tonight. A Wind Advisory has been
issued for north central South Dakota.

- Combination of strong winds and humidity below 40 percent will
lead to High to Very High fire danger this afternoon across central
and north central South Dakota. An increase in humidity will limit
fire weather concerns further east.

&&

.DISCUSSION...
Issued at 247 AM CDT Mon Sep 14 2026

Rain showers and weak thunderstorms are moving into the forecast
area from the southwest this morning. Expectations over the next
couple of hours is that coverage of these showers and storms will
continue to expand, covering most if not all of the forecast area by
sunrise. These showers and storms are fueled by a 40-50 knot low-
level jet moving across the region this morning, strengthening to 55
knots as it progresses eastward after sunrise. In addition to the
storm development, this low-level jet is expected to bring strong
southerly gusts up to 40 miles per hour to much of northeastern
South Dakota and western Minnesota this morning. Still anticipating
the highest rainfall totals over eastern South Dakota, and NBM
median values through tonight sit around 1"-1.25" over Codington
County and the surrounding counties. As mentioned in previous
discussions, there is an outside chance of flooding potential given
the abnormally high PWAT values advected into the region (around
1.5"-1.75", well above the 90th percentile for mid-September), full
saturation through the profile, and a warm cloud layer depth of
roughly 11-12k feet. However, antecedent conditions are not very
favorable for flooding, and much of eastern South Dakota in
particular is under D0-D1 drought. Storm motion is also expected to
be fairly quick, although with the low-level jet in play the
development of training storms cannot be ruled out. Perhaps the
biggest limiting factor though is the lack of CAPE. Generally
expecting less than 1000 J/kg of MUCAPE, although it should be noted
that values seem to be increasing over the past couple of forecast
cycles. Still, not expecting much in the way of strong thunderstorms
or severe weather with this development, but will continue to keep a
close eye through the morning hours.

After the passage of the cold front, winds will turn northwesterly
and increase. The strongest winds, gusting upwards of 35 miles per
hour, are expected along and west of the Missouri River,
particularly over Corson and Dewey Counties. NBM probability of
reaching 45 mile per hour gusts in those two counties sits in the 40-
60% range from around noon Monday through midnight Monday night.
Elsewhere, both NBM and HREF probabilities of reaching wind advisory
criteria struggle to reach more than 20-30%. However the combination
of the strong cold air advection coming in behind, a shallow diurnal
inversion at the surface, and the tendency for the NBM in particular
to verify near the 90th percentile under this type of setup, there
is some slightly increased confidence given to needing an Advisory
over Campbell/Walworth/McPherson/Edmunds Counties. Therefore, have
expanded the coverage on the previous advisory, running the new
additions from 00Z-09Z Tuesday. The potential failure point here
would be if the inversion holds, but given the expected temperature
drops at 850mb (nearly 10 degrees Celsius in 6 hours), the profile
will likely than not be able to maintain some degree of mixing to
the surface.

In addition to Advisory level criteria, winds during the afternoon
will be the driver behind some elevated fire weather concerns. A
brief warmup in temperatures this afternoon out ahead of the front
over central and north central South Dakota will push afternoon
humidity down below 40 percent over the westernmost column of
counties in the Aberdeen CWA. The combination of the wind and low
humidity, in addition to fuel status considerations, leads to the
Grassland Fire Danger Index reaching Very High in that area.
Counties just to the east of the previously mentioned area will
reach High Grassland Fire Danger as well.

By mid-week, the upper-level setup will transition to near-zonal
flow and a positively tilted trough over the western CONUS. This
setup will allow for additional shortwaves into the region, leading
to more chances for rain later in the week. Specifically, Wednesday
and Friday both sport chances for rain at this time. Model soundings
for both of those days do not look particularly favorable for any
severe weather potential, although perhaps a touch to early to say
for certain on Friday in particular. Also expecting a gradual
warming trend with this setup, with median high temperatures
reaching near-normal (mid-70s) over the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1241 AM CDT Mon Sep 14 2026

Terminals KABR,KATY,KPIR,KMBG

VFR/MVFR low/mid-level cloud deck between 2-5kft will gradually
lower to MVFR/IFR during the next 12 hours. Showers with some
embedded thunder have developed across western into central
South Dakota. Gradually, the rain shield will expand and move
northeast, passing over all four terminals. Later this evening,
winds will switch to west-northwest and increase to 20 to 30
knots with gusts up to 40 knots. There could be some low level
wind shear around Monday night.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory from 11 AM this morning to midnight MDT tonight
     for SDZ003-015.
     Wind Advisory from 7 PM this evening to 4 AM CDT Tuesday for
     SDZ004-005-009-010.
MN...None.

&&

$$

DISCUSSION...BC
AVIATION...10