422
FXUS63 KABR 151126
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
626 AM CDT Fri May 15 2026

.KEY MESSAGES...

- Red Flag warnings today for much of central, north central and
northeast SD/western MN.

- Temperatures again in the upper 70s/low 80s, west winds of 25 to
40 mph, strongest along the ND/SD state line, afternoon humidity
down to around 15 to 20%.

- Dry again for Saturday.

- Storm chances increase Saturday night, continue through Sunday,
followed by rain Monday.

- Slight Risk (2 of 5) mostly focused across central and northeast
South Dakota Sunday afternoon.

&&

.DISCUSSION...
Issued at 242 AM CDT Fri May 15 2026

Temperatures have dropped along with the winds under clear skies
early this morning.

The forecasted upper level pattern is initially mainly zonal, but
with a trough developing over the northern Rockies for the weekend.
It makes a slow transition east while deepening, ejecting 3-4 waves
before moving east around mid-week. The upper level pattern that
follows is weak and disorganized.

Today: Zonal flow aloft, with a northeast-southwest gradient in
850/700mb temperatures. There is a plume of slightly warmer mid
level air overhead in the morning, followed by slightly subtle
cooling through the afternoon. This may slightly enhance winds given
deep mixing, dry conditions and ample sunshine.  There is no
gradient across the state however, so winds are primarily due to
this degree of mixing.  Will go with NBM winds, which have trended
slightly downwards. Even going 90th percentile only yields the
minimum wind required for a Red Flag in Jones/Lyman/Buffalo
counties. As such, will remove Buffalo, Lyman and Jones counties
from the Red Flag. Farther north, the 75th percentile meets/exceeds
criteria and as such its much harder to articulate a need for
cancellation or changes.

Up along the ND/SD state line, where westerly flow mixed winds are
close to 30kts, we could see some localized blowing dust, and the
dust model is picking up on this, however at these wind speeds and
lacking an organizing feature/boundary, should not see widespread
issues. Temperatures today about the same as Thursday sighting only
slight changes in airmass/mid level temperatures.

Friday night: A weak wave crosses through mainly North Dakota. CAMS
are hinting at some light precipitation coming in from the west.
RRFS hints at the mid level deck above 12kft associated with warm
advection. Shouldn`t really do anything.

Saturday: An upper level ridge strengthens overhead, with southwest
flow aloft later in the day. Mid-level warm advection develops
across the area late in the day, and BUFKIT profiles show some mid-
level moisture, albeit up around 8-10kft, is limited in thickness,
and is above a deep dry subcloud layer. Again, aside from some cloud
cover, little change in low/mid level temperatures means another day
with highs around 80F and afternoon humidity down around 20%. Winds
have shifted to easterly around weak high pressure moving overhead
and east. Return flow on its backside, with an increasing gradient
ahead of a lee low, around 12mb across the state. Mixed winds only
yield upper teens (kts) however NBM deterministic values are showing
some spots west river up around 30kts.

Saturday night/Sunday: This warm advection continues to strengthen
overnight into Sunday morning, with elevated convection out ahead of
a surface low/inverted trough that evolves across the western
Dakotas, with a secondary low developing over southeast South
Dakota. Additional support aloft provided by a southwest flow
shortwave early in morning and then a second later in the
afternoon/evening at which point we are looking at mainly saturated
profiles and elevated instability as the surface low moves up along
the SD/MN state line. How much moisture is expected with this round?
Given the convective nature, NBM probabilities should be taken with
a grain of salt, and in fact the 25th-75th range reflects these
uncertainties, with the lower bounds of just a tenth or two (maybe
up to 1/3) with a higher range closer to 1 inch to inch and 1/4.
Now, I`ll point out the first round of moisture is under weak mid
level low, meaning slow moving storms. This is countered by the
elevated nature of convection with less instability or ascent. The
afternoon/evening round occurs under stronger mid level flow
limiting storm duration.

As for severe weather potential, as mentioned before there is strong
mid level shear. Surface low moving up across the far eastern CWA
provides the best location for surface based instability, though
this is late into the evening/overnight. 75th percentile surface
based instability is around 1000j/kg CAPE, however profiles are more
suggestive of elevated convection with straight line hodographs,
supporting fast moving storms with supercell structure. Still lots
of time and any shift or adjustments to timing will likewise impact
the severe weather threats.

Monday/Monday night: Surface low traverses northeast across
Minnesota. Some wrap around moisture evident in deterministic models,
dry elsewhere before another shortwave lifts up across the area.
Profiles are less convective in nature, suggesting a more stratiform
nature of precipitation. NBM 24 hour moisture probabilities still show
a lot of range, with the lower 25th down around a tenth or two, with
the higher 75th over 1".

Tuesday/Wednesday: On the back side of the upper trough, much cooler
mid level temperatures move into the region. 850mb temperatures are
on the order of -1 to -2C Tuesday morning with some moderation for
Wednesday morning. That said, this is on the backside of a low and
not associated with a strong high pressure system. As such, much
depends on timing of cloud cover and daytime heating driven strato-
cumulus.  Still NBM temperatures are in the low to mid 30s raising
the specter of possible frost.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 626 AM CDT Fri May 15 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to continue through the period, with
winds gusting out of a westerly direction 20-30kts 16Z today-00Z
Saturday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 9 PM CDT /8 PM MDT/ this evening for
     SDZ003>011-015>017-021.
     Red Flag Warning until 7 PM CDT /6 PM MDT/ this evening for
     SDZ018>020-022-023-033>037.
MN...Red Flag Warning until 9 PM CDT this evening for MNZ039-046.

&&

$$

DISCUSSION...07
AVIATION...06