269
FXUS63 KABR 031115 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
615 AM CDT Thu Sep 3 2026

.KEY MESSAGES...

-There is a Marginal risk (level 1 of 5) for severe storms to
develop over far northeastern SD and west central MN late this
afternoon into the early overnight hours. The primary threats will
be hail up to 2 inches in diameter and wind gusts of 60 to 70 miles
per hour.

- Warming trend continues through the week, peaking at 10 to 20
degrees above normal Friday and Saturday. Widespread highs in the
low to mid 90s are expected those days.

&&

.UPDATE...
Issued at 615 AM CDT Thu Sep 3 2026

Updated for 12Z Aviation discussion below. In addition, only
minor tweaks to the going forecast, primarily to add some fog
mention based on obs/webcams and to align Sky/PoPs with the
lasted obs/trends.

&&

.DISCUSSION...
Issued at 126 AM CDT Thu Sep 3 2026

Early this morning, there is warm frontal boundary sitting over
portions of SD. The warm front, in addition to a bit of instability
(RAP shows 1000-2000 J/kg along the boundary) are helping some
isolated showers and storms to form and move over portions of
central and northeastern SD. While a low level jet over north
central is helping to provide some shear to sustain the storms for a
bit, there is still a strong cap over the area that is helping to
stop the storms from becoming to large and severe. The showers and
storms should stay below severe criteria. However, with stronger
DCAPE values (over 1000 J/kg) currently over central and
northeastern SD, some stronger wind gusts could make it to the
ground especially as the showers and storms are dissipating. These
showers and storms should be gone by mid-morning.

Southerly winds today will help to push warm, moist air into central
and northeastern SD, with high temperatures in the mid 80s to low
90s. This will help to create a nice environment for showers and
storms to develop, with the models showing CAPE values of 1000-3000+
J/kg over northeastern SD this afternoon and evening. An upper-level
shortwave moving over SD this afternoon will help to support a lee
of the Rockies surface trough moving into central and northeastern
SD, which could provide a source of lift. However, the warmer
temperatures moving in aloft will help to create an inversion which
will cap the environment to storm development. Models show the
temperatures at 850 mph getting up between 20-26 degrees C over
northeastern SD and west central MN, which will be hard to overcome.
Due to this cap and the inversion, the models vary what could
happen, lowering confidence in the storm chances late this afternoon
into tonight. Some models have scattered showers and storms develop
in ND, where there are some cooler temperatures aloft that the
storms are able to overcome. These storms start more discreet as
they move southeast into far northeastern SD and west central MN
before moving east during the evening and becoming more of a line of
storms. Other models have the warm front moving a bit slower, which
could then cause storms to try and develop to the south and
southeast of the forecasting area. These storms will then stay out
of northeastern SD and west central MN. In either scenario, there
will be mid-level lapse rates between 6-8 C/km and bulk shear values
of 35-45 kts over northeastern SD and west central MN. If storms do
develop or move into this environment, they will be capable of
producing large hail and strong winds. Because of the cap that could
prevent storms from developing, SPC has shifted the slight risk out
of far northeastern SD and west central MN and moved the marginal
risk to only cover those areas. The primary threats from the storms
will still be hail up to 2 inches in diameter and wind gusts of 60-
70 mph if anything were to develop. The threat for storms should
move out of the area during the late evening.

Friday and into the weekend, an upper-level ridge is forecast to
start developing to the south and over parts of SD. This will help
to move some warmer temperatures into central and northeastern SD.
Temperatures will be 10 to 20 degrees warmer than normal, with highs
in the mid 80s to mid 90s. During Friday and through the weekend,
upper-level shortwaves are forecast to move along the top of the
ridge, which will be situated over central and northeastern SD,
helping with shower and storm development. Some models forecast some
drier air moving in Friday for the day, which could help to keep
showers and storms from developing. However, other models have some
moisture moving in Friday evening and overnight. In these models, as
another frontal boundary tries to move through during that time,
some scattered showers and storms then look to develop over central
SD overnight into Saturday morning. The NAM forecasts there to be
1000-2000 J/kg CAPE values over the area during Friday night which
will help with storm development along the frontal boundary, but
there does also look to be a bit of a cap from warmer temperatures
aloft that will have to be overcome for things to develop. A low
level jet looks to develop Friday night, which will help to support
the longevity of the storms. Lapse rates of 6-7 C/km will help with
some hail development in these storms, though most of them look to
stay below the severe threshold.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 615 AM CDT Thu Sep 3 2026

Terminals KABR,KATY,KPIR,KMBG

Expect VFR conditions to prevail today as a warm front lifts
northeast across the area this morning, associated with a
surface low located over northwest and north central SD. As that
occurs, expect winds to shift to a south-southwestelry direction
today. At this time, expect the area to be capped and limit
thunderstorm potential at KATY (expect daytime potential to the
southeast of the site and then northeast this evening as
thunderstorms move southeast out of eastern ND). The previously
mentioned surface low will move east into eastern SD late this
afternoon and evening, shifting the winds around to a northwest
and eventually northeasterly direction. With the slightly cooler
air and nearby thunderstorm outflow boundaries moistening the
air, could see some patchy fog in northeast SD. At this time,
not enough confidence to mention in the KATY TAF.

&&

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

&&

$$

UPDATE...SRF
DISCUSSION...12
AVIATION...SRF