828
FXUS63 KUNR 172009
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
209 PM MDT Sun May 17 2026

.KEY MESSAGES...

- Another round of rain, with snow in Black Hills, is likely later
  tonight into Monday.

- Much colder to start the week but warmer temps return by late week.

- Low-end chances for rain return later this week.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 200 PM MDT Sun May 17 2026

A change in the weather pattern is ongoing for NE WY and W SD.
Cooler air has been sliding southeast into the area today. It was
able to get some showers and thunderstorms going earlier in the
day but now that the cold front has completely pushed through the
CWA, chances for severe weather have diminished. Other impacts
from this cooler air has been the much cooler afternoon temps in
the 40s to 50s and we wont get much warmer than that. Also, wind
gusts increased as the front pushed through with wind gust
reports upwards of 35 to 40 mph.

For tonight, temps will continue to cool to well below-normal, to
the upper 20s to 30s. Coldest temps will be found in NE WY where
a Freeze Warning has been issued. This will most likely be
repeated and expanded Monday night. Winds will remain a little
elevated through tonight and tomorrow, at around 5 to 15 mph
before diminishing Monday night.

As far as precip goes for tomorrow, an upper level disturbance
will quickly move through, keeping widespread passing precip
chances in the area. Through Monday night, total QPF amounts are
up to .25 inches, highest amounts in the SD plains.

Because we are much cooler behind the cold front, we are looking
at a taste of winter-like weather. For starters, some of the
precip will likely fall as snow in the higher elevations of the
Black Hills. At this times, upwards of 2 to 6 inches of snow is
possible. A big question is - will it accumulate or will it melt
as it hits the ground? Either way, a slushy, wet snow is likely
late tonight into Monday.

Temperatures are still expected to be well below normal for mid-
to-late May. Mondays temps look to struggle to warm up before
falling for Monday night. But the cooler temps wont last long as
highs in the 50s are likely Tuesday with a warming trend expected
for the rest of the week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1150 AM MDT Sun May 17 2026

Showers and storms are ongoing over central and south central SD,
including PHP and ICR. Low VFR to MVFR/IFR conditions have
overspread much of the region this morning. A cold front is
pushing through, shifting winds out of the NW with gusts 25 to 35
knots. Showers and thunderstorm chances persist through the
afternoon along the front, best chance for strong to severe storms
across south- central SD. Slow improvement to VFR is expected
across NE WY and western SD after 19z as the front pushes
eastward.

Another round of rain/snow develops during the latter half of the
forecast period (after 18/07-09z) with widespread MVFR/IFR
conditions moving in overnight.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WY...Freeze Warning from 5 AM to 10 AM MDT Monday for WYZ054>056-
     058>060.
&&

$$

DISCUSSION/KEY MESSAGES...GS
AVIATION...Dye