340
FXUS63 KABR 211327 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
827 AM CDT Thu May 21 2026

.KEY MESSAGES...

- There is a 50-80 percent chance of 1/2 inch or more rainfall
  occurring Friday into Friday night.

- Turning much warmer Sunday through next week, around 10 to 20
  degrees above normal, with highs in the 80s to near 90.

&&

.UPDATE...
Issued at 824 AM CDT Thu May 21 2026

So far, just a few pockets of sprinkles activity this morning.
Low level moisture return flow really starts ramping up later
this evening. No changes planned, at this time, to the today
period forecast.

UPDATE Issued at 615 AM CDT Thu May 21 2026

UPDATE for 12Z Aviation discussion

&&

.DISCUSSION...
Issued at 205 AM CDT Thu May 21 2026

Weak mid level warm advection and subtle shortwave responsible for
light showers and sprinkles this am, which will lift northeast.
Otherwise we maintain a gradient with winds out of the south
gusting to 20 to 35 mph.

As for the wave Friday, timing is late tonight west river with some
convective nature but really just skinny CAPE in modest shear, which
weakens with loss of daytime heating. Some of that might leak into
the Missouri valley before dissipating. After 06Z a more
consolidated (24 hours ago it was 2) negatively tilted wave lifts up
across the area. CAMS take most of the day Friday to lift this
system up across the CWA and it may take the northeast until early
Saturday before everything has lifted north. The 25th percentile is
around 1/4 inch west river to 1/2 inch in the northeast while the
75th is closer to 1 inch so still a bit of range. Just some skinny
or shallow CAPE depending on model and location, so overall
assessment is mainly just rain/showers with little thunder.

Thereafter, there is a secondary wave aloft 12Z Saturday overhead.
This, and daytime heating may lead to additional light shower
activity. NBM is dry at this time, something to watch.

We have brief zonal flow overhead/upstream for Sunday/early Monday,
with flow becoming southwesterly aloft as a trough deepens across
the Pacific Northwest. This increasing heights and temperatures aloft
translates to warmer conditions for Sunday - Thursday. 700mb
temperatures increase to +6 to +10C, about a standard deviation
above climo. High temperatures that timeframe still 10 to 20F above
climo.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 615 AM CDT Thu May 21 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue over the next 24 hours at ABR/ATY.
MVFR to potentially IFR ceilings will return after 06Z Friday.
Winds will gust 20-30kts through the day today, with the weakest
winds at ATY.

&&

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

&&

$$

UPDATE...10
DISCUSSION...07
AVIATION...06