588
FXUS63 KABR 031740 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1240 PM CDT Sun Aug 3 2025

.KEY MESSAGES...

- An active pattern continues with showers and thunderstorms
  expected through Tuesday. Any additional heavy rain east of the
  James Valley maintains a flood threat due to saturated soils.

- There is a marginal risk (1 out of 5) for severe storms each day
  through Tuesday for portions of the area from the James Valley
  west. Strong winds will be the primary threat each day.

&&

.UPDATE...
Issued at 1232 PM CDT Sun Aug 3 2025

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 1028 AM CDT Sun Aug 3 2025

No changes planned to the today period forecast.

&&

.DISCUSSION...
Issued at 441 AM CDT Sun Aug 3 2025

An upper low/MCV continues to spin around Sisseton this morning. To
the south of the center, there are some convective bands that have
developed within some stronger moisture convergence on a llj. Rain
rates in the convection have been as much as 2 inches in an hour,
though the main concern is residence time due to training and slow
motion. So far, this has focused in southern Spink county where
there`s an areal flood warning out. Will need to continue to
watch this system`s evolution as it progresses east today over
areas that are already saturated. Additional heavy rain and
flooding are possible.

There is a marginal risk for severe storms today through Tuesday,
generally for portions of areas from the James Valley west. Today,
the focus point is across south central SD. However, some of the hi-
res CAMs have storms developing as far east as the James Valley
around 23z, likely due to a shortwave moving through the upper flow.
At the sfc, forcing is farther west off a southwest SD/western NE
low that pushes into south central SD this evening. It`s pretty
diffuse and shear is almost non-existent until after 3z. Even lapse
rates are only moderately steep - around 6 to 7 C/km. For Monday and
Tuesday, drier air moves in from the west. Lapse rates steepen on
the edge of the drier air. This boundary is likely what will drive
any convection late Monday and Tuesday, along with any shortwaves
that move through the flow. One thing to note, though, is that the
NSSL WRF and the FV3 continue to place convection farther east and
are overall more intense than other hi-res.

Models diverge a bit in the latter half of the week as to whether a
system will bring additional showers and thunderstorms Thursday into
Friday or remain farther north and east. Ensembles hold onto some 15-
35 percent chances for now.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1232 PM CDT Sun Aug 3 2025

Terminals KABR,KATY,KPIR,KMBG

The TAF valid period is going to be a mix of VFR/MVFR conditions
(mainly cigs bouncing around). Daytime heating is raising cigs and
also dissipating low cloud coverage. However, later tonight after
03Z, the low cigs are forecast to return, at least at KMBG, KABR
and KATY, and stick around into Monday until daytime
heating/mixing has a chance to improve things. Confidence is also
pretty low in shower/thunderstorm timing and coverage this
afternoon into tonight. Most guidance has precipitation pretty
isolated/widely scattered. The likelihood of a shower or
thunderstorm occurring over/near any of the 4 terminals is pretty
low.

&&

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

$$

UPDATE...10
DISCUSSION...20
AVIATION...10