Altamont, South Dakota Weather Forecast Discussion

825
FXUS63 KABR 171142 AAA
AFDABR
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
642 AM CDT Wed Sep 17 2025
.KEY MESSAGES...
- Low pressure will move into the area today and begin a prolonged
  period of wet conditions that will persist through the end of
  the work week. Highest chances for rainfall will be today
  through Thursday night where much of the area has a 60-90
  percent chance for showers and thunderstorms.
- Rainfall amounts over the next 3 days include a widespread 1-2
  inches across most of the area with localized amounts of more
  than 2 inches.
- Drier conditions and seasonal temperatures are expected to return
  this weekend into early next week.
&&
.UPDATE...
Issued at 632 AM CDT Wed Sep 17 2025
The aviation discussion has been updated for the 12Z TAFS.
&&
.DISCUSSION...
Issued at 451 AM CDT Wed Sep 17 2025
The surface weather map analysis early this morning shows an
elongated stationary frontal boundary draped from southwest to
northeast from central NE into southeast SD and into southwest and
central MN. Low pressure anchored on that front is working across
far southeast SD this morning. An inverted sfc trough extends to
the northwest from that low across southeast SD into north central
SD. Scattered showers and a few thunderstorms have been working
toward the northwest across central SD near the vicinity of that
trough early this morning with more widespread showers and storms
building across NE into far southeast SD. This is all just the
beginnings of a large slug of moisture that will work into the
region today.
As the aforementioned low across far southeast SD shifts northeast
along the stationary front today, it will be quickly filled with a
more organized system from the south. Low pressure at the sfc and
aloft will become a nearly stacked system over the next 24 hours
across northern NE into southern SD. That slug of moisture in NE
this morning will continue lifting northward this morning and into
our area throughout the day. Instability will remain limited thanks
to the extensive cloud cover that will overspread the region.
Nonetheless, enough dynamics will accompany this system leading to
embedded thunderstorms within the general area of rain. This
activity should begin to fill in and become more widespread by the
midday and afternoon hours. Thunderstorm activity is expected to
remain sub-severe today and throughout the duration of this multi-
day event. However, heavy rains will become the primary concern as
this moisture lifts north and then back to west-northwest with time.
NBM probabilities of seeing at least 1 inch or more of rainfall in a
72 hour period ending Saturday morning remains fairly high with a 50-
80 percent chance of this to occur across most of the forecast area.
NBM probabilities of seeing at least 2 inches or more in that same
time frame range from a 40-70 percent chance across central portions
of SD. This has prompted WPC to issue a Slight risk (level 2 of
4)for excessive rainfall for portions of central SD today into
tonight.
This storm system is progged to sit and spin over SD through the
daytime hours on Thursday into Thursday night with continued chances
for rainfall. By Friday morning, this low will be situated across
the Dakotas/MN border region. From there, it`s expected to gradually
shifting to the north toward the Canadian border by late Friday into
Saturday. The associated upper level portion of this system is
anticipated to shift across the Dakotas into MN late Friday into the
beginning of the weekend. Rainfall will gradually taper off on
Friday into Friday night and be mostly out of our forecast area by
the first half of the day on Saturday. Drier conditions will then
set up for most of the weekend and persist into the beginning of
next week. Temperatures will remain cool and below normal during the
duration of this wet period before they gradually warm back to
seasonal levels during the course of the weekend into next week.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 632 AM CDT Wed Sep 17 2025
Terminals KABR,KATY,KPIR,KMBG
Periods of showers and thunderstorms will continue to overspread
central and northeast South Dakota today as an area of low
pressure organizes and slowly moves north into the region. There
may be some initial VFR conditions early in this TAF cycle at
KABR/KATY, but those conditions should be short-lived as the rain
pushes into those terminals. Otherwise, trends through the day
will feature a gradual lowering of cigs at all terminals with MVFR
conditions setting in sooner or closer to midday today at
KPIR/KMBG versus the farther east 2 terminals. Eventually, these
lower cigs will move into KABR/KATY. They may even set in sooner
than this at any terminal depending on the intensity of the
showers and storms. Vsbys will also gradually lower in time with
general MVFR/IFR conditions expected during the latter half of
this TAF cycle.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Vipond
DISCUSSION...Vipond
AVIATION...Vipond

NWS ABR Office Area Forecast Discussion