667
FXUS63 KABR 041445 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
945 AM CDT Mon Aug 4 2025

.KEY MESSAGES...

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

- There is a marginal to slight risk (1 to 2 out of 5) for severe
  storms today and Tuesday for portions of the area from the James
  Valley west. There is a marginal risk for severe storms on
  Wednesday, mainly across the east. Strong winds and large hail
  will be the primary threats each day.

&&

.UPDATE...
Issued at 939 AM CDT Mon Aug 4 2025

Two mid-level impulses/areas of weak to moderate synoptic-scale
lift are noted in water vaport this morning. One over the CWA is
aiding in the furtherance of elevated showers/storms over the
James River valley region. As the 850hpa trof/axis and any
remaining llj activity wanes late this morning into the early
afternoon, this area of convection should gradually dissipate with
time. The other area of lift is over western SoDak this morning
and could work to aide in afternoon/evening convection further
back over the Missouri River valley, especially once the llj
redevelops later this evening, pointing toward the western
Dakotas/northern high plains. Currently deep layer shear of less
than 25 kntos and MUCAPE of generally 1500J/kg or less will
increase later this afternoon/evening out west where there will be
plenty of sunshine to destabilize a non-capped atmosphere, so the
stage may be set for a few strong to potentially severe storms
(mainly) west river. No changes currently planned to the today
period forecast.

&&

.DISCUSSION...
Issued at 326 AM CDT Mon Aug 4 2025

The active weather pattern is expected to persist through much of
the work week with continuous chances for additional showers and
thunderstorms. Currently, there is a marginal to slight risk for
severe storms this evening and Tuesday and a marginal risk for the
entire region on Wednesday. Today, the focus for storms remains west
of the James Valley, associated with a Rocky Mountains low and a llj
overnight. Additionally, shortwaves riding through the upper ridge
will contribute to forcing. Lapse rates steepen today and Tuesday,
as well, as drier mid level air pushes in from the west. On Tuesday,
that pseudo dry line and the sfc low push further toward central SD
which also expands the slight risk across the Missouri River valley.

By Wednesday evening, there`s more zonal flow aloft, but that
persistent lee side troughing remains with the southerly llj
increasing CAPE and instability. Steep lapse rates will lend
themselves to strong wind gusts. But, Wednesday`s severe weather is
more contingent on shortwave activity and post-storm environment
after early week storms.

The GFS and ECMWF both push the sfc low into South Dakota Thursday
with the drier air mass. The GFS, in its typical drier fashion,
attempts to keep precip more confined to ND and northern MN until a
post frontal wave moves through late Friday with an upper trough. EC
and NBM maintain 20 to 40 percent pops Thursday night through
Saturday morning. The upper trough barrels through the Dakotas
Friday night into Saturday morning bringing slightly cooler temps
after a seasonable work week.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 609 AM CDT Mon Aug 4 2025

Terminals KABR,KATY,KPIR,KMBG

Another chaotic mix of vsby and cigs this morning with some MVFR
fog floating around and a mix of IFR to VFR patchy stratus. Expect
vsby to improve by 15z with cigs improving around 18z at all
sites. Showers and thunderstorms are expected again today but with
low confidence in spatial coverage and timing.

&&

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

$$

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