253
FXUS63 KUNR 180514
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1114 PM MDT Wed Jun 17 2026

.KEY MESSAGES...

- Near-normal temperatures Thursday with highs in the 70s.
  Slightly warmer-than-normal temps return Friday and Saturday.

- Calmer northwest winds likely tomorrow. Winds swing to the
  east/southeast late Friday, still on the calmer side at around
  5-15 mph.

- Improved fire weather conditions for the rest of the week -
  lighter winds but minimum RH values around 20 to 25% in NE WY
  and SW SD.

- Isolated showers and storms possible through Thursday night.
  Better chances for storms this weekend.

&&

.UPDATE...
Issued at 932 PM MDT Wed Jun 17 2026

03z surface analysis had weak ridge over the northern Plains with
a right entrance region of a 120kt jet streak creating some AC
over the southwest half of the CWA. Few sprinkles/light showers
have developed with forecast updated to account. Otherwise, going
forecast in good shape. Northwest flow and a couple of weak waves
to produce a few more chances of isolated shra/TS through Friday.
Then, stronger disturbances arrive for the weekend with
southeasterly boundary layer flow increasing moisture and chances
for shra/TS. Strong/severe thunderstorms possible Saturday over
the south given moderate buoyancy/increasing shear, but cloud
cover and eventual position of wavy frontal boundary will affect.
QPF amounts this weekend look beneficial with ~50% chance many
folks will get 0.75" by Monday morning.

&&

.DISCUSSION...(This Evening Through Wednesday)
Issued at 122 PM MDT Wed Jun 17 2026

It`s been a windy Wednesday today. Most of the wind gust reports
around western SD have been upwards of 55 mph but a few isolated
reports of near 60 mph came in from Philip, Wasta, and Cottonwood
around 1PM.

Going forward, a low pressure system spinning near the west side
of the Hudson Bay is still our main weather maker for the short
term forecast. It`s giving the CWA northwest flow with just enough
upward vertical motion to get some showers and thunderstorms
going in the upper great plains. So far, most of the activity has
been contained to our north in North Dakota and in eastern SD
while the western SD counties have been dry for the most part,
save for a few cells that have been short-lived.

Looking ahead to tonight through tomorrow night, we`ll continue
the chances for isolated showers and non-severe storms trying to
drift in from the north and northwest. Temperatures will be near-
normal with overnight lows in the 40s to low 50s and afternoon
highs in the 70s to near 80. Winds will still be out of the
northwest but at a much calmer 5 to 15 mph with gusts nearing 20
to 25 mph.

Friday and the weekend will see the weather pattern change. The
northwesterly flow will slide to a more westerly flow as a high
pressure builds over the desert southwest. This will bring back
warmer temps and more widespread thunderstorm chances for the
weekend. The SPC has a risk for severe weather in Nebraska for
now, but we wouldn`t be surprised if parts of southern SD end up
being included in future updates.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1112 PM MDT Wed Jun 17 2026

Mainly VFR conditions are expected through the forecast period.
Isolated showers and thunderstorms will be possible across
northwest SD and the Black Hills area Thursday afternoon and
evening.

&&

.FIRE WEATHER...
Issued at 932 PM MDT Wed Jun 17 2026

Humidities on Thursday and Friday will bottom out in the 20s with
winds gusting to 15 to 25 mph. Elevated fire weather conditions
will continue. Cooler and wetter conditions develop for the
weekend with increasing chances for wetting rains.

&&

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

$$

UPDATE...Helgeson
DISCUSSION...GS
AVIATION...15
FIRE WEATHER...GS