793
FXUS63 KABR 081734 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1234 PM CDT Tue Jul 8 2025

.KEY MESSAGES...

- There is a Marginal risk (level 1 of 5) for severe storms
  Wednesday afternoon as well as Thursday afternoon.

- Seasonal temperatures are expected during the 7 day forecast,
  with the exception of Wednesday and Thursday, when high
  temperatures could bump back up into the low to mid 90s
  throughout and west of the James River valley.

&&

.UPDATE...
Issued at 1231 PM CDT Tue Jul 8 2025

Aviation discussion updated below for the 18Z TAFs.

UPDATE Issued at 1022 AM CDT Tue Jul 8 2025

Patches of low clouds across the eastern CWA are showing signs of
dissipating recently. Had earlier adjusted sky cover grids to
better reflect satellite trends. Fog is no longer a concern as
well. Surface high pressure in place today will keep winds rather
light across the region as highs rise into the upper 70s to upper
80s.

&&

.DISCUSSION...
Issued at 422 AM CDT Tue Jul 8 2025

With leftover moisture from the precipitation yesterday as well as
stable air and light, variable winds at the surface, pockets of fog
have formed over northeastern SD, and is likely to continue to
spread into the morning. Areas with lighter fog coverage will likely
dissipate once the sun has risen, however other areas with heavier
fog coverage might take until mid morning for the fog to dissipate.

The upper-levels have a ridge starting to move east towards and then
over SD today into Wednesday. This helps to develop and support high
pressure forming at the surface over eastern SD. In addition to the
high surface pressure, dry mid-level air moving into central and
eastern SD helps to keep precipitation from developing today. This
warm mid-level air will also help to increase the temperatures over
the next coming days. This will lead to high temperatures Wednesday
and Thursday getting into the low to mid 90s west of the Prairie
Coteau with heat indicies forecast to reach the upper 90s to 100 in
this area on Wednesday.

Wednesday, the models show in the upper-levels, a ridge riding
shortwave moving over western and central SD. At the same time, a
lee of the Black Hills surface trough looks to develop over the I-90
corridor into Jones and Lyman counties as well as a lee of the
Rockies surface trough extending into the far western Dakotas by the
end of the day, though the location of these boundaries do vary
slightly in the models. Southerly winds on Wednesday help to move
warm, moist air into central SD along the edge of the high pressure
over eastern SD. Models are showing increased instability Wednesday
morning into the afternoon over central SD ranging from 2500 to 4000
J/kg. With the surface troughs providing a source of low level focus
in the moist and unstable environment, isolated storms could develop
over or near portions of central and north central SD by the end of
peak heating. Deep layer shear of 30-35kts could cause these storms
to become multicellular to supercellular in nature. Additionally,
higher mid-level lapse rates (8+ C/km) could help in creating large
hail/severe wind hazards in these storms. An eye will need to be
kept on Wednesday to see where the surface troughs set up, as that
is where storms could develop.

The active pattern continues into Thursday and Friday as an upper-
level shortwave moves over the state Thursday and an upper-level
trough works its way in behind the shortwave on Friday. The
ingredients needed for thunderstorms on Thursday and Friday appear to
be present. However, deep layer shear needed for organized/severe
thunderstorms appears to be lacking at this time. The probability of
precipitation are in the forecast for the end of the week. Will need
to continue to monitor instability and shear parameters as we get
closer to Thursday and Friday. Behind the boundary on Friday,
surface high pressure builds in again for the weekend with
considerably cooler, drier air in place on Saturday. However, much
warmer air could be working back in again by Monday.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1231 PM CDT Tue Jul 8 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. Light north-
northeast surface winds today will gradually become south-southeast
on Wednesday.

&&

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

$$

UPDATE...TMT
DISCUSSION...12
AVIATION...TMT