654
FXUS63 KABR 311200 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
700 AM CDT Sun Aug 31 2025

.KEY MESSAGES...

- Fog is expected this morning over northeastern South Dakota.
  Visibility will get as low as a quarter of a mile, and a Dense
  Fog Advisory is in effect for the James Valley and east.

- Showers and weak thunderstorms will continue through the
  weekend. Severe weather is not expected with this system.
  Heavier rain or stationary storms may also pose an isolated
  flooding threat.

- A cold front will move through on Tuesday, with a 20 to 40
  percent chance of rain. The remainder of the week is expected
  to stay dry.

- Below normal temperatures are expected for mid week. Highs will
  be in the upper 50s to mid 60s, 10 to 20 degrees below normal.
  Low temperatures Thursday morning may dip into the upper 30s.

&&

.UPDATE...
Issued at 658 AM CDT Sun Aug 31 2025

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.DISCUSSION...
Issued at 238 AM CDT Sun Aug 31 2025

Once again showers linger over central South Dakota this morning,
but the bigger concern at the moment is fog over northeastern South
Dakota. As of ~08Z this morning, visibility reductions down to 1
mile have been observed, but existing fog remains patchy for the
time being. Coverage is expected to expand as sunrise approaches,
and visibility may get down to a quarter of a mile at times.
Therefore, a Dense Fog Advisory has been issued for Brown/Spink
counties and east, in addition to McPherson and Edmunds counties.

Low pressure center to the south will continue to progress eastward
today, continuing scattered showers to weak thunderstorms through
the afternoon and evening today. Once again the focus area will be
over central South Dakota. Parts of central South Dakota, namely
Stanley county, have seen a decent amount of rain over the past
couple of days, and soils have become saturated. Even in those
areas, the threat of flooding is offset a bit by rainfall rates
remaining low. However, the area could see another inch of rain over
the course of the next 24 hours, with locally higher amounts
possible. The good news is that the highest rainfall totals are
forecast to be a bit further east than where the saturated soils
are, more into Lyman/Buffalo/Hyde/Hand counties.

By Tuesday, a cold front is expected to move across the forecast
area, bringing the next chances for storms. Main threat area will be
across northeastern South Dakota into western Minnesota, where a
plume of 1000-2000 J/kg of surface based CAPE will be available,
along with modest shear of 20-30 knots. This will create what will
most likely be an isolated severe threat Tuesday. Wind is currently
the main expected threat, given dry air aloft, strong low-level
lapse rates, and upwards of 1000 J/kg of DCAPE in the area. Hail
could also be a threat, although would prefer to see higher MUCAPE
and stronger mid-levels lapse rates when looking for severe hail
potential.

Behind this front, the forecast area will be under strong northerly
flow aloft due to a strong trough digging in over the eastern CONUS.
This cold air advection will bring high temperatures down into the
60s for Wednesday and Thursday, 10 to 20 degrees below normal for
early September. Cold air advection may weaken with a slight
progression of the trough eastward by the weekend, so temperatures
may warm up closer to climatological normal by the end of the
forecast period.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 658 AM CDT Sun Aug 31 2025

Terminals KABR,KATY,KPIR,KMBG

Dense fog over northeastern South Dakota is the main aviation
concern this morning. Fog has been a bit inconsistent in visibility,
but has been reducing visibility to LIFR and VLIFR conditions at
KABR and KATY. A Dense Fog Advisory is in effect until 10 AM CDT for
the James Valley and east, and conditions are expected to begin to
improve after sunrise. Once the fog clears, MVFR ceilings will take
over for a couple of hours before lifting further to become VFR.

Showers are lingering over central South Dakota today, and will
continue to do so through around 00Z. A weak thunderstorm is
possible, but given the uncertainty and sparse areal coverage that
is expected of these thunderstorms, no thunder has been added to the
TAFs at this time. These showers could reduce visibility and
ceilings to MVFR status, with the main impacts coming to KPIR and
occasionally KMBG of the TAF sites. The low pressure system
supporting these showers will continue to progress eastward today,
and the latter half of the TAF period should be clear of rainfall.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 10 AM CDT this morning for SDZ005>008-
     010-011-018>023.

MN...Dense Fog Advisory until 10 AM CDT this morning for MNZ039-046.

&&

$$

UPDATE...10
DISCUSSION...BC
AVIATION...10