676
FXUS63 KABR 110136 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
836 PM CDT Sun May 10 2026

.KEY MESSAGES...

- Temperatures will fall into the low 30s over portions of
  northeastern SD overnight into Monday morning. Patch frost to
  areas of frost will be possible, with a Frost Advisory in
  effect.

- On Monday, continued dry conditions with relative humidity
  falling to 15 to 30% and southerly winds gusting 30-40 mph
  will bring high Grassland Fire Danger Index values to portions
  of central to northeastern SD. Red Flag Warnings or Fire
  Weather Watches are in effect for portions of mainly central
  SD for Monday afternoon.

- High to very high Grassland Fire Danger is forecast Tuesday
  and Thursday as winds gust 35 to 45 mph, with a few locations
  gusting to near 50 mph. Relative humidity over much of the
  area will fall into the 15 to 30% range.

- High temperatures Monday through Saturday will be in the 70s
  and 80s, highest Thursday through Saturday when temperatures
  will be around 20 degrees above normal.

&&

.UPDATE...
Issued at 831 PM CDT Sun May 10 2026

No changes to the Frost Advisory for the overnight hours.
Southerly winds still look to increase after midnight, but will
take longest to do so over the eastern CWA. Thus, radiational
cooling setup is better further east where temps are more likely
to fall between 32 and 36 degrees.

&&

.DISCUSSION...
Issued at 249 PM CDT Sun May 10 2026

The 19Z surface weather map showed 1025mb high pressure over
southeastern Manitoba, with a ridge extending across the Dakotas and
northern MN. This ridge will exit across MN as the main area of high
pressure settles across the Upper Great Lakes Monday. By 18Z Monday
our forecast area will be stuck between the exiting high and an
elongated trough of low pressure set up from the southern
Saskatchewan/Manitoba border down through the Black Hills. Southerly
winds will be in force, with temperatures being about 20 degrees
higher than today. Temperatures will rise in the 70s east of the
James River, and mainly rise into the 80s west of the James River.
Increasing winds with winds gusting 30 to near 40 mph, hot, and dry
conditions will result in high to very high Grassland Fire Danger
Index values Monday afternoon, especially west of the James River.
Given coordination with fire management personnel, the short grasses
are green across much of the area. Still, taller dry grasses are
still being receptive to fire movement. Our ongoing mainly dry
weather has dominated now for nearly 2 weeks. A Fire Weather Watch
remains for Brown/Spink Counties west. The highest confidence in
reaching Red Flag Warning criteria was over south central SD
(Jones/Lyman/Stanley Counties), where relative humidity falls to 15
to 25%. This is the driest area Monday. The main concern there is if
wind will be strong enough during the driest part of the day to
allow for 3 hours of 20% or lower relative humidity and wind gusts of
25 mph or more. As we move through the afternoon, winds will
diminish in this area. Later shifts will need to monitor the latest
trends to see if the relative humidity will be low enough, as winds
will be gusting at or above 25 mph. Even going with some of the
lowest guidance, confidence was low in reaching criteria.

Expect a cold front and shifting winds Monday night into Tuesday
morning around 02Z over north central SD, 05Z near the James River,
and 08Z over far northeastern SD and west central MN. We continue to
message not only the hot, dry, and windy conditions, but the wind
shift that could impact any ongoing or new fires.

Light showers, and even a rumble of thunder will be possible with
the passage of the cold front, mainly over our eastern and southern
counties. A wetting rain (0.01" or more) is not expected at this
time.

Winds increase out of the northwest Tuesday (cold air advection
peaking 00-06Z Tuesday), with gusts of 35-45 mph during the day.
Given these winds, lowing dust will be possible Tuesday Aberdeen to
Clark and west, so mainly west of the Prairie Coteau of northeastern
SD (where less precipitation has fallen over the last couple of
weeks and crops are minimal).

High pressure will be overhead Wednesday. After lighter winds
Wednesday, winds will be out of the south on Thursday. Minimum
relative humidity much of the week will be 15 to 30%, with mainly
dry weather continuing. The strongest winds are expected Thursday,
with a 40-60% chance of winds gusting over 45 mph east of the
Missouri River. A Wind Advisory may be needed for Thursday. Highs
Thursday will be in the 80s to low 90s (warmest of the next 7 days).

There are some differences in the track/strength of the next surface
low Thursday night into Friday. Temperatures will only fall a few
degrees, and still mainly be in the 80s through the upcoming weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 634 PM CDT Sun May 10 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. Light winds
this evening will gradually increase from the south-southeast
late tonight and through the day Monday. Gusts by mid/late
morning and afternoon will approach 30 knots.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Frost Advisory from 3 AM to 9 AM CDT Monday for SDZ005>008-010-
     011-017>023.
     Fire Weather Watch from Monday afternoon through Monday
     evening for SDZ003>006-009-010-015>018-034>037-051.
     Red Flag Warning from 1 PM CDT /noon MDT/ to 9 PM CDT /8 PM
     MDT/ Monday for SDZ033-045-048.
MN...Frost Advisory from 3 AM to 9 AM CDT Monday for MNZ039-046.

&&

$$

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