779
FXUS63 KUNR 162345
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
545 PM MDT Fri May 16 2025

.KEY MESSAGES...

-Winds will continue to slowly wane through afternoon with the
 strongest winds having ended

-Frost is possible tonight across portions of far western SD and
 northeast WY

-Unsettled pattern continues into next week with another strong
 low pressure system bringing appreciable rain to the region
 Sunday and Monday.

&&

.DISCUSSION...(This Evening Through Friday)
Issued at 209 PM MDT Fri May 16 2025

The pattern remains fairly active into next week with mean
western CONUS toughing supporting another deep low pressure system
into the region early next week with widespread rains Sunday into
Monday. Upper low over the northern Plains is shifting back east
and will exit the region as another potent system digs into the
western CONUS. The strongest winds have ended across the region,
with still some lingering gusts over 60 mph on the Plains. Have
trimmed the high wind warning and wind adv down some and will
continue to chip away on the headlines as the system exits the
region. Rain will also shift east and end through afternoon with
all places expected to be dry by late evening. Skies will clear
out with winds dropping off many areas tonight into Sat morning,
supporting the formation of frost across far western SD and
portions of northeast WY. The highest probs for frost will be
across NW SD and portions of northeast WY where the lightest winds
and coldest temps will occur. Weak high pressure will build into
the region Sat before the next system starts to affect the region.
Temps will warm up some Sat, but still be below seasonal norms.
Pos theta-e adv will ensue, supporting chances for showers and
storms in the late afternoon and overnight Sat, moving in from the
SW. As the system shifts east, the associated trowel will remain
over the region, supporting a long duration of rain Sunday
afternoon through Monday night as appreciable moisture wraps into
this system. Models still are indicating widespread amounts over
an inch across much of the FA, with the highest amounts (over 2
inches) expected along the eastern slopes of the BH where upslope
enhancement will be in place. Some high elevation snow will also
be possible with this system, esp areas above 6kft where a few
inches will be possible. Things will dry out by the middle of the
week, however semi-active westerly flow will persists with near
daily chances for showers continuing along with seasonally cool
temps.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 517 PM MDT Fri May 16 2025

Widespread MVFR/IFR conditions in RA will persist over portions
of the SD plains and Black Hills this the evening but gradually
improving to VFR from west to east tonight. Otherwise VFR
conditions are expected through the forecast period. Gusty
northwest winds will quickly decrease around sunset.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Warning until 6 PM MDT /7 PM CDT/ this evening for
     SDZ001-002-012>014-031-032-043-044-046-047-049-072-073-077-
     078.
     Frost Advisory from 1 AM to 9 AM MDT Saturday for SDZ001-002-012-
     013-030-031-042-073-075-076-078.
WY...Frost Advisory from 1 AM to 9 AM MDT Saturday for WYZ056-058>060.
&&

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...13