230
FXUS63 KABR 111540 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1040 AM CDT Sat Apr 11 2026

.KEY MESSAGES...

- Areas of drizzle along/east of the James valley today. Maybe
  a few hundredths overall. Another round of isolated showers
  (20%) overnight/early Sunday.

- Fog expected across portions of northeast SD late this
  afternoon into the nighttime hours. Visibility below 1 mile
  possible.

- Well above normal temperatures Sunday, with highs in the 70s
  to low 80s (15 to 25 above normal). A west wind with gusts 25
  to 35 mph. Grassland Fire Danger increases to High/Very High
  category Sunday.

&&

.UPDATE...
Issued at 1029 AM CDT Sat Apr 11 2026

Plenty of stratus along/east of the Missouri River and matched
sky grids to better align with western edge of stratus deck over
central SD. Still appears the back edge should start nudging
eastward later this afternoon, but the eastern two-thirds of
the CWA look to stay cloudy all day. Radar shows light showers
from earlier this morning have departed to the east, leaving
behind areas of drizzle. Radar returns resemble more of a
drizzle look, and RAP soundings support this as well, with
drying aloft taking place through the remainder of the day while
keeping a deep moist layer in the lower levels of the
atmosphere. Several web cams across the eastern CWA show
evidence of drizzle/very light rain, with VSBY reductions in
KATY/other locations as well. Changed up wx type in the grids
to reflect drizzle the remainder of the day. Any redevelopment
of showers this afternoon may be just east of the CWA, but can
change back to mention showers if anything were to develop this
far west. With the abundance of clouds across the east, lowered
high temps a few degrees. The western CWA still looks to get
rather mild with highs in the 70s.

&&

.DISCUSSION...
Issued at 1227 AM CDT Sat Apr 11 2026

Return flow on the back side of high pressure, with warm
advection ceilings around 10kft. 1/2km winds out of the south are
also on the increase, around 40kts which will continue to spread
east overnight.

NAM BUFKIT profiles indicate more stratus coming up from Nebraska,
and we can see that ceilings in southern Nebraska are falling down
to 2kft. This should end up across far eastern South Dakota
later today. There isn`t much of a wave aloft, with ridging
overall through the day. With the moisture profile, this is
primarily a drizzle type event, with little indication of
moisture ever above 9kft, when saturation is at its thickets.
This last from a little after 12Z through about 21Z with drying
aloft forcing the stratus to shrink down to 3-5kft thickness,
which is probably not high enough to generate moisture.
Adjusted the jumpy NBM POPs to something more consistent across
the east.

The stronger southwest flow shortwave comes up through
northwest South Dakota early Sunday, a little slower progression
in comparison to 24 hours ago. Not a lot of mid-level moisture
with this feature, and mid level lapse rates only support skinny
elevated CAPE. As such, not a lot of evidence for widespread
moisture with this wave. Still seeing an isolated GEFS plume or
two with 0.1" to 0.2" of moisture. Most CAMS have an isolated
blip or two moving out of western South Dakota, so cant totally
discount the NBM 20% chances. This lasts through about 12-13Z in
the CAMS, and 15Z in the NAM after which the surface low lifts
into northern Minnesota. NBM has us dry after 12Z, totally fine.

A really good mixing day expected for Sunday. 1/2km winds are
westerlies starting around 40kts at 12Z. The surface gradient is
about 5-6mb north to south. Mixed winds are around mid 20kts. As for
temperatures, the core of the warmest 850mb temperatures associated
with the southwest flow shortwave is also overnight, departing to
the east by 15/18Z. Very subtle cold advection follows, which will
only aid in mixing. Plus we have the departing wave leading to cloud
free conditions. So the main question is how warm and dry as we look
to potential enhanced fire weather conditions. We`re still at the
NBM 10th percentile for highs Sunday. 00Z HRRR is latching onto
slightly drier dewpoints as well. That said, HREF probability
of lower than 20% humidity is only about 20% down along the
White River. Additionally, area webcams are showing a rapid
greenup in the wake of last weeks 1/2 to 1 inch of moisture.
Will bump up high temperatures closer to the 50th percentile
given such favorable mixing conditions, trend dewpoints just a
tad lower. Again, winds are low end for Red Flag, and without
additional info to improve confidence, no headlines for now.

Ridging for the start of Monday, with a north south temperature
gradient off a surface high to our north. Weak low pressure develops
in advance of a southwest flow wave late in the day. NBM POPs are
around 20-30%, but represent mainly mid level moisture/instability.
GEFS plumes again showing a blip here and there of precipitation,
but nothing overwhelming. Another wave is set for later Tuesday as
the trough out west opens up and migrates east. There is a brief
period Wednesday/Thursday with zonal flow aloft before the next
upper trough comes in from the west. Behind that system,
deterministic models bring in a colder airmass, with GEFS 850
temperatures down to about a standard deviation below climo.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 625 AM CDT Sat Apr 11 2026

Terminals KABR,KATY,KPIR,KMBG

Winds out of the south-southeast will gust 22-30kts today,
before diminishing to around 20kts tonight over PIR/MBG. We`re
starting out with MVFR/VFR ceilings at PIR, with ceilings dropping
at to IFR at ABR/ATY between 15Z and 20Z today with IFR fog possible
as well. Low level wind shear will develop at all locations around
03Z Sunday with winds 35-55kts just above the surface.

&&

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

&&

$$

UPDATE...TMT
DISCUSSION...07
AVIATION...06