925
FXUS63 KUNR 051949
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
149 PM MDT Sun May 5 2024

.KEY MESSAGES...

-Windy with increasing chances for showers through Monday.

-Strong winds possible Monday night and Tues across northwest SD.

-Unsettled and cool the remainder of the work week.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 148 PM MDT Sun May 5 2024

Deep upper low is moving across the western CONUS and will
provide windy and unsettled weather for the upcoming week. The
western CONUS upper trough continues to shift east into the
Rockies supporting ongoing pressure falls over the region. This
has resulted in gusty SE winds across the SD plains. Winds have
gusted to around 55 mph on the NW SD plains with winds continuing
this afternoon. Winds will taper off some most places in the
evening, but will persist/increase downwind the Pine Ridge later
tonight across scentral SD. Hence have extended the wind adv there
for this, deciding to go through Monday given gusty SW winds with
the passage of the dry line. Additional wind headlines will
likely be needed for tomorrow on portions of the SD plains, but
given the expected lull tonight, will let the night shift decide
on area/extent. Did issue a high wind watch for NW SD Monday
afternoon through Tues afternoon as the low deepens and CAA with a
strong pressure gradient support a potential high wind setup
there as the core of LL winds advect across that region.
Otherwise, pos theta-e adv with a weakening cap will allow for a
thunderstorm or two over NE WY late this afternoon/evening, with
convection developing and shifting NE across NE WY and far western
SD tonight. There will be chances for showers most places tonight
with the main moisture surge/WAA, although the best chances will
be across mainly NW SD. Strong storm system will then move into
the plains Monday, with the sfc trough/dryline shifting east
across southwest through scentral SD, supporting breezy SW winds.
Severe threat will remain south and east of the FA, although gusty
winds are likely along the sfc trough, which may spawn some weak
convection across scentral SD. Extended wind adv should cover
these concerns. Further west, deformation rains will spread into
the region Monday morning along with gusty westerly winds. As the
upper low stalls and then slowly migrates east, winds, rain
showers, and cool weather will persist through Wed night. Again,
warning level winds are possible Monday night/Tues across NW SD as
dry slotting interacts with fast flow aloft through dynamic
mixing. Rain will change to snow in the higher elevations of the
Black Hills Monday night with some light accums possible. However,
somewhat better chances for snow accums are possible Tue night
into Wed when colder air advects into the region, with some snow
lingering into Thur. Things will begin to slowly warm up and dry
out toward next weekend as the upper low finally exits the region
and a ridge of high pressure builds across the western CONUS.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1119 AM MDT Sun May 5 2024

South-southeast winds of 25 to 35 mph with gusts of 45 to 50 mph
will continue this afternoon and evening, strongest across the
western SD plains. MVFR to IFR conds will develop tonight as
moisture advects north ahead of a low pressure system. Expect
showers and isolated thunderstorms tonight with more widespread
rains across the NW half Monday.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 11 PM MDT this evening for SDZ001-002-
     012>014-026-030>032-042-043-072-073-075-078.
     High Wind Watch from Monday afternoon through Tuesday afternoon
     for SDZ001-012-013-025-072-073-078.
     Wind Advisory until 6 PM MDT /7 PM CDT/ Monday for SDZ044-046-
     047-049-076-077.
WY...High Wind Watch from Monday afternoon through Tuesday afternoon
     for WYZ060.
&&

$$

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