871
FXUS63 KUNR 051122
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
522 AM MDT Sat Sep 5 2026

.KEY MESSAGES...

- Above average temperatures remain in the forecast. The hottest
  days will be Saturday with highs in the mid to upper 90s but 80s
  and 90s are expected Sunday and Monday.

- Elevated fire weather conditions are expected through Saturday.

- Best chance for passing showers and thunderstorms is on Sunday
  into Sunday night.

&&

.UPDATE...
Issued at 931 PM MDT Fri Sep 4 2026

No major changes to the forecast. Expired the RFW as winds have
decreased, although RH remains in the teens to low 20s across NE
WY and portions of SW SD and the southern Black Hills. Poor
overnight RH recovery again tonight (30-45 percent) across NE WY
and portions of the Black Hills. Near-critical conditions expected
again tomorrow given hot (widespread mid to upper 90s) and RH in
the teens, although winds will remain below RFW criteria. Still a
day to watch given dry conditions and anomalously warm
temperatures.

Isolated storms possible tomorrow, although weak flow and large-
scale forcing will limit coverage and overall severe risk. Enough
instability exists for transient severe hail/wind. Additional
storms possible Sunday, some of which may be strong to severe.
Beyond the severe risk, lightning is a concern regarding new fire
starts for the weekend.

&&

.DISCUSSION...(This Evening Through Friday)
Issued at 1219 PM MDT Fri Sep 4 2026

Isolated passing thunderstorms tracked through western SD earlier
today. And latest satellite and radar imagery shows clear skies
moving into the area. But there are hints at low-end chances for
spotty thunderstorms again later this afternoon into evening. A
few boundaries are still showing up in western SD and northern
Nebraska. Also, some hi res model guidance hints at storms
redeveloping in southwest SD this afternoon. That being said,
there is still some decent capping in the atmosphere but if
storms are able to get going, they will track northeast and are
not expected to be severe. Otherwise, tonight is looking like
another mostly dry sky night with overnight temps in the 60s.

For the weekend, afternoon highs will remain well above normal for
early September. Saturday`s highs will be in mid to upper 90s for
the SD plains and low to mid 90s in NE WY. Sunday`s highs will be
in the upper 80s to mid 90s.

Best precip chances on Saturday are contained to the Black Hills
and the area to the northeast, and in central SD. SPC has placed
a marginal risk of severe storms in SD. But Sunday into Monday,
an upper level trough looks to swing over Montana and that trough
could bring passing thunderstorms to the area. The SPC has placed
a marginal severe risk out for Sunday over the Black Hills and to
the north and machine learning severe weather models are still
hinting at a risk of severe weather centered over the CWA Sunday
and Monday. Stay plugged into the forecast through the weekend
for updates.

Beyond Monday, low end chances for precip lingers in the forecast
with a slight cooling temperature trend.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Sunday Morning)
Issued At 519 AM MDT Sat Sep 5 2026

VFR conditions are generally expected through the period. Isolated
storms may develop this afternoon and evening, and could impact
KRAP. Have introduced a PROB30 for 19-23Z today. Brief MVFR
conditions may be possible in heavier rain.

&&

.FIRE WEATHER...
Issued At 1219 PM MDT Fri Sep 4 2026

Warm and dry conditions are still found around the area today,
especially over northeastern WY and parts of western SD. A Red
Flag Warning has been issued for today for parts of the western
fire zones.

Temperatures will be hot again tomorrow and Sunday with highs
well into the 90s to near 100 degrees. Very low humidity is also
expected to continue, dropping to near 15 to 20 percent in the
afternoons across northeastern WY and portions of far western SD.
The winds are looking to be a little calmer this weekend, so at
this time, Red Flag Warning thresholds are not expected to be met
so a Red Flag Warning extension is not expected at this time.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

UPDATE...SE
DISCUSSION...GS
AVIATION...Dye
FIRE WEATHER...GS