395
FXUS63 KABR 281946
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
246 PM CDT Mon Sep 28 2026

.KEY MESSAGES...

- There is a marginal risk (level 1 out of 5) for severe
  thunderstorms this evening into the early overnight hours.
  There is a potential for a few stronger storms with 1" hail
  and wind gusts up to 60 mph.

- Rain over central SD will expand across northeastern SD and
  west central MN tonight, before exiting east during the day
  Tuesday.

- There is a 25-65% chance of rainfall over 0.5" this evening
  through the day Tuesday, and around an 85% chance over north
  central SD between the Missouri and James Rivers. Heavy rain
  is possible with any stronger storms over mainly central SD,
  with localized flooding especially over areas that received
  heavy rain today.

&&

.DISCUSSION...
Issued at 246 PM CDT Mon Sep 28 2026

Radar estimates of 2 to nearly 5" of rain fell over far northeastern
Corson/northwestern Campbell Counties during the morning to early
afternoon hours, with an estimated 2-3.5" over portions of western
Dewey County. These areas will be a concern with additional shower
or thunderstorms producing steady or heavy rain tonight into early
Tuesday morning. PW values averaging 1.45" will increase to near
1.7" 00-03Z Tuesday over central SD, before shifting to areas that
have experienced little to no rain over the past 24 hours. The daily
mean PW from the SPC sounding climatology page is around 0.7", with
the our values nearing the daily max values.

Winds out of the south gusting 15 to 30 mph will slowly weaken this
evening. Expect rain to continue over central South Dakota into
Tuesday morning. There is a marginal risk, or level 1 out of 5, for
severe thunderstorms over portions of central South Dakota this
evening into the early overnight hours, where a few stronger storms
with 1" hail and wind gusts up to 60 mph will be possible. Heavy
rain is possible with any stronger storms, with localized flooding
especially over areas that have already received heavy rain. The mot
likely time period for strong to near severe storms will be from 23
Monday-06Z Tuesday. Rain will expand across northeastern South
Dakota and west central Minnesota early Tuesday morning, before
coming to an end Tuesday afternoon as an area of low pressure
crosses west to east across South Dakota. The winds out of the south
will shift out of the northwest during the day. There is a 25-65%
chance of rainfall over half an inch from the evening hours through
the day Tuesday, with around an 85% chance over north central South
Dakota between the Missouri River and James River. Plenty of low
level moisture will remain. For example, relative humidity will
bottom out in the 60 to 80 percent range Tuesday east of the
Missouri River, and still not fall much below 50 percent west of the
Missouri River.

Fog will likely be a concern Wednesday morning over northeastern SD
into west central MN per the NAM and ECMWF ENS visibility meteograms
page, and if the trend continues, will be added to our ongoing
forecast.

Looking farther out, there is some uncertainly on the
strength/timing of ridging over the western U.S., with either more
zonal flow or ridging as we move into early next week. Stay tuned.
Currently we are expecting temperatures of 5-10F below normal for
this time of the year starting Thursday. Other than a 20% chance of
light rain Saturday morning over northeastern SD, dry weather is
forecast Wednesday through early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1220 PM CDT Mon Sep 28 2026

Terminals KABR,KATY,KPIR,KMBG

MVFR to VFR conditions will continue this afternoon as some
scattered rain showers move over northern SD. These scattered
showers, and potentially some storms, could move over KMBG and KABR
during the afternoon. Then another round of showers and storms will
move into central this evening and move over northeastern SD
overnight into Tuesday morning. Ceilings will decrease to MVFR and
IFR and potentially LIFR at times tonight into Tuesday morning with
low clouds along with these showers and storms. There could be some
lingering drizzle and fog on the back edge of the showers Tuesday
morning. Stronger winds aloft Tuesday morning into the afternoon
will help to push the lower cloud bases and lower visibilities to
the east and out of SD through the afternoon.

&&

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

&&

$$

UPDATE...12
DISCUSSION...06
AVIATION...12