970
FXUS63 KABR 181752 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1252 PM CDT Mon Aug 18 2025

.KEY MESSAGES...

- There is a slight (level 2 out of 5) to marginal risk (level 1 out
of 5) for severe weather over central SD today. Main threats are for
severe wind gusts of 60 mph and large hail.

&&

.UPDATE...
Issued at 1239 PM CDT Mon Aug 18 2025

The aviation discussion has been updated for the 18Z TAFS.

UPDATE Issued at 1037 AM CDT Mon Aug 18 2025

The dense fog that was observed earlier across a good portion of
central and northeast SD has lifted and visibilities have improved
in most locales. Therefore, let the Dense Fog Advisory expire on
time at 10 AM CDT. Monitoring a few showers across northwest SD at
this hour and they may clip parts of Corson County in the next
couple of hours, so may need to add some pcpn chances there if
they look like they`ll hold together. Otherwise, the forecast for
the remainder of the today period remains on track.

&&

.DISCUSSION...
Issued at 226 AM CDT Mon Aug 18 2025

As of 07z, there are storms moving through southeastern SD, and most
of these storms should stay out of northeastern SD. However the
northern edge of the storms could still build into southern
northeastern SD and some smaller storms that develop ahead of the
main area of storms could affect that area too. The other concern
for this morning is the fog that is developing over central and
eastern SD from the excess moisture left by yesterday`s
precipitation. This fog could reduce visibilities in areas, and
those driving should take caution. The fog should dissipate during
the morning once the sun rises.

The lee of the rockies surface trough continues to sit over western
SD while the frontal boundary stays parked over southern SD today.
The environment over central and eastern SD continues to stay fairly
wet as well as unstable, with CAPE values forecast to get above 2000
J/kg Monday evening, especially over central SD. The surface trough
over western SD could help to develop and push storms east into
central SD, while the frontal boundary over southern SD could
develop storms that affect south central SD. Models are also showing
bulk shear values of 30-40 kts over south central SD Monday
afternoon, which could help with storm organization. The bulk shear
and CAPE values start to decrease later in the evening, which could
help to decrease storm chances during overnight. Storms will mainly
have the risk for strong to severe winds and large hail. On another
note, elevated wildfire smoke continues to move into central and
eastern SD today. This elevated smoke should stay aloft and not
reach the surface.

The upper and mid levels start to shift and build high pressure over
AZ/NM Monday evening into Tuesday. This then helps to develop a
ridge that reaches up over western SD and parts of central SD by the
mid-week. At the surface, the frontal boundary finally decides to
start moving overnight into Tuesday with some weak high surface
pressure building in behind the front. Despite there being some high
pressure over central and northeastern SD, there is still a moist
environment with some instability present through the day Tuesday
that could help with shower and storm development. The lack of
fronts and lifting mechanisms helps to reduce the chances for
development, however there is still the possibility that something
could try to pop up. The models are also showing there to be weaker
bulk shear values in the area, which will help to reduce the ability
for storms to organize if they do get started.

As the ridge builds to the north, some drier air is push up in to WY
and western SD, with some variation in the models as to any of the
drier air moving into central SD. Even without the drier air in
central and eastern SD, there should thankfully be a break in the
storms and precipitation Wednesday into Thursday afternoon. Though,
the occasional pop-up showers cannot be fully ruled out at this
time. Temperatures will also be affected by the ridge, with them
starting to increase. The warmest temperatures are forecast for
Thursday, reaching the low to mid 90s over central SD and low to
upper 80s over northeastern SD.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1239 PM CDT Mon Aug 18 2025

Terminals KABR,KATY,KPIR,KMBG

VFR will generally remain the prevailing conditions for all
terminals during this TAF cycle. The exception will be at
KABR/KATY during the early morning hours on Tuesday due to low
stratus and fog. MVFR/IFR cig and vsby`s will be possible at
these two TAF sites. There is an isolated shower west of KMBG
early this afternoon. Will have to monitor and amend the forecast
at this terminal if it continues on its current trajectory. There
remains some uncertainties with respect to more organized
convection expected across western and central South Dakota later
this afternoon. If it materializes, some of this activity could
affect KPIR/KMBG late this afternoon and this evening, but with
low confidence left it out of the forecast at this time.

&&

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

$$

UPDATE...Vipond
DISCUSSION...12
AVIATION...Vipond