915
FXUS63 KABR 150604
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
104 AM CDT Wed Apr 15 2026

.KEY MESSAGES...

- Warming trend continues. Temperatures today top out in the 70s
  (15 to 20 degrees above normal) and Thursday into the upper
  70s to mid 80s (15 to 30 degrees above normal).

- The combination of warm temperatures and southerly winds of 25
  to 30 miles per hour result in High to Very High Grassland
  Fire Danger Thursday. A Fire Weather Watch is also in effect
  for late Thursday morning into the late afternoon.

- A cold front will move through the area Thursday night,
  leading to below normal temperatures (highs in the 40s) and
  precipitation Friday and Saturday. Precipitation starts out as
  rain Friday afternoon before transitioning to snow as colder
  air moves in. Overall not a lot of moisture with this system.

&&

.DISCUSSION...
Issued at 1242 AM CDT Wed Apr 15 2026

Isolated elevated shower activity early this morning, with
BUFKIT profiles and regional observations indicating ceilings up
around 8-10kft or higher. NAM BUFKIT profiles also indicate a
fairly dry layer of air below, so that will really limit what
reaches the surface. Added sprinkles through the overnight. CAMS
are also highlighting the northeast for another round of fog
formation, and we`ve already seen Wheaton down to 1/4 mile.

For Today, the weak wave responsible for the ongoing activity
has shifted into western Minnesota, with a second wave over
central Nebraska, both heading northeast with the influence now
east of the CWA. We end up in broadly diffluent flow aloft as a
stronger wave comes into the Pacific northwest. Good mixing
conditions for the day with a light southwest component to the
winds. HREF probability of exceeding 20 mph only tops out at
20-40% for a few hours in the morning when we first mix out,
then drops to zero. NBM deterministic highs are about 1 to 4F
below the 50th percentile, and with ample sun and mixing winds,
bumped temperatures up. Afternoon humidity across much of the
area will be from 20 to 30%, and the HREF probability of falling
below 20% is actually from 40 to 60% across our west river
counties. But again, winds are going to fall well below criteria
for Red Flag. Across the east, mainly the far northeast, NAM
BUFKIT profiles also indicate some weak/shallow convective
instability. Profiles suggest convection limited to between 5
and 10kft which may be enough to generate moisture. CAMS only
have a few blips. Have added a 20% chance up across the
northeast.

Wednesday night, flow aloft continues to be diffluent, resulting in a
lee low forming over eastern WY/MT and the western Dakotas. This
increased the gradient, though only about 10mb across the state.
Increased flow is southerly, with 1/2km winds of 25 to 40kts. There
will also be warm advection through the overnight hours, though no
elevated instability is indicated in the NAM. As we continue into
Thursday, flow aloft is southwesterly, with southwesterly low level
flow, though the lee low weakens into more of an inverted trough
stretching northeast to southwest across the state.  Inverted V
style profiles are depicted by the NAM, with a few j/kg CAPE above
the 0C level, up around 12kft. No POPs with this profile, but along
with the system derived winds being strong, this may add additional
gustiness as a fire weather wrinkle.

As for temperatures Thursday, again, NBM falls around the 10th
percentile, with a 5 to 8 degree cool bias vs the NBM 50th
percentile. This again is likely due to a significant thermal
gradient across northwest South Dakota and south central North
Dakota and the array of possible ensemble placements. Winds for most
of the area during the day are also in a warm advection regime,
meaning the NBM should provide the cap for highest wind gusts
(outside of the aforementioned convection) so this will give us a
good idea of whether we`ll meet Red Flag. NBM gives us 50 to 70%
probability to exceed 25 mph and a 30 to 50% probability for winds
in excess of 30 mph. That means the potential for a fairly
widespread Red Flag wind wise. For afternoon humidity, the
deterministic NBM is around 20 to 25% with the far northwest and
northeast up over 30%.

Cold front moves through during the overnight hours, with a wind
shift and increase. Strongest pressure rises are out in western
South Dakota, but the gradient from southeast to northwest is
about 16 to 20 mb. NAM/GFS BUFKIT profiles indicate status
follows, with mixed winds in the 25 to 35kt range. Concern is
that any ongoing fires will experience a sudden shift in
trajectory. The gradient persists through Friday, at about
20mb across the state, keeping winds up.

We still go from a standard deviation above climo for 850mb
temperatures Thursday to a standard deviation below climo by
Saturday, with a 30-40 degree temperature difference between highs
Thursday in comparison to Friday/Saturday.

Trends for moisture: NBM POPs have dropped, and shifted the
total moisture west. Still only averaging a tenth of an inch or
less. GEFS is likewise a tenth or two, with a few blip up
around a half inch. NBM probability of a 1/4 inch are also down,
up north of Mobridge its only about 30-40% with lower
elsewhere. Profiles still suggest a transition to snow as well,
but with ground/air temps wouldn`t expect it to last.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1242 AM CDT Wed Apr 15 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions and winds around 10kts or less will continue over the
next 24 hours.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Thursday morning through Thursday
     evening for SDZ005>008-010-011-016>023-033>037-045-048-
     051.
MN...None.

&&

$$

DISCUSSION...07
AVIATION...06