107
FXUS63 KABR 151404 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
904 AM CDT Sat Aug 15 2026

.KEY MESSAGES...

- Patchy to areas of fog will continue through the mid/late
  morning mainly James Valley and eastward.

- Scattered showers and weak thunderstorms will be possible
  through the afternoon mainly over portions of south central
  through northeastern SD and west central MN ahead and along a
  cold front. No severe weather is anticipated, however, heavy
  rainfall is possible.

- Average to slightly below average temperatures expected
  through the weekend.

&&

.UPDATE...
Issued at 902 AM CDT Sat Aug 15 2026

Allowed the Dense Fog Advisory to expire this morning.
Visibilities have improved to above a quarter of a mile, though
some lighter fog may linger until late morning.

Expanded pops farther north and east this morning as a line of
showers and isolated thunderstorms have begun developing in the
past half hour. Latest model guidance holds these showers across
east central SD through the morning.

&&

.DISCUSSION...
Issued at 148 AM CDT Sat Aug 15 2026

As of 1am, a storm cluster consisting of moderate rain and a few
lightning strikes are tracking eastward along/ahead of the frontal
boundary over north central SD and into ND where forcing is better,
however, CAPE and lapse rates are pretty weak with decent bulk shear
between 30-40kts. None of the CAMs really have a good handle, either
not showing this storm at all or should be dissipating by now. So
if it holds together it will continue to skirt along the ND/SD
border bringing the potential for lighting and brief heavy
downpours. Areas of light rain/drizzle per WAA flow continues over
far northeastern SD into western MN as well. 00Z ABR sounding
indicated a nearly saturated sounding, especially at the lower
levels, per southeasterly flow near the surface and southwesterly
flow between 700-500mb. This is causing fog/low stratus over
portions of northeastern SD/western MN per latest obs and webcams
showing a reduction in visibility and MVFR/IFR cigs. So have fog
mention in the grids through the mid morning.

Within this southwest flow, weak embedded shortwave energy
continues to track across the Northern Plains with a more notable
shortwave to the south of the CWA in Nebraska tracking
east/northeast. An inverted trough/weak low is currently over
central ND with its frontal boundary extending into central SD and
its weak low lying along the boundary. By 12Z, the low is forecast
to over northeastern ND/MN with the cold front extending through
northeastern SD into NE, with only a slight movement northeast of
the low and east with the cold front. Models indicate scattered
chances of showers and thunderstorms here and there ahead and along
this boundary, mainly over south central through northeastern SD/MN
where better forcing resides, however, differences in timing and
location do vary between the CAMs so stuck mostly to the NBM which
keeps it more broadbrushed. CAPE values this afternoon will be
around 1000 j/kg or less and shear under 30kts, therefore, any
storms that occur will be short lived and below severe limits as
lapse rates remain weak. However, monsoonal moisture being pulled in
per southwest flow is causing PWAT values of 1.7 to almost 2", west
to east across the CWA, so any rain shower and/or weak thunderstorms
(especially slow moving) could produce heavy rainfall.

By this evening, the region will be behind the cold front, in
northwest flow at the surface and winds switching to zonal aloft. A
high pressure system will track into the region from the northwest
and center itself over the Dakotas Sunday keeping the area dry. This
high will shift a bit east Sunday night with pops returning over
central SD (40-65%) Sunday night into Monday morning. As the high
exits the region, a stronger shortwave and its west to east oriented
cold front will drop out of Canada and over the region bringing our
best chance for moisture with widespread pops of 50-70%. Still a few
days out to nail down specifics or whether severe weather will be a
threat.

Temperatures remain around average to slightly below average through
the weekend, ranging in the 70s to around 80. Little bit warmer on
Monday with highs in the upper 70s to the upper 80s before cooling
back into the 70s behind the cold front and incoming high Tuesday
and Wednesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 629 AM CDT Sat Aug 15 2026

Terminals KABR,KATY,KPIR,KMBG

LIFR/VLIFR conditions at KABR in dense fog and low stratus will
persist for the first couple hours of this forecast cycle
before improving to MVFR by mid morning and eventually back to
VFR late this morning. Elsewhere, KATY will see MVFR/IFR
conditions also due to fog and low stratus along with a mention
of VCSH through about mid morning before showing signs of
improvement back to VFR this afternoon. VFR conditions will be
more prevalent at KPIR/KMBG through the next 24 hours. Northwest
winds could gust around 20 kts this afternoon.

&&

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

&&

$$

UPDATE...20
DISCUSSION...MMM
AVIATION...Vipond