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779
FXUS63 KUNR 031946
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
146 PM MDT Fri May 3 2024

.KEY MESSAGES...

-- Changed Discussion --
-Rain shifting east out of the forecast area this evening.

-Warmer and breezy this weekend.

-Strong storm system early next week with the potential for
 several hazards: locally heavy rain Monday/Tuesday (northeastern
 Wyoming/northwestern South Dakota), high winds
 Tuesday/Wednesday, some snow for the Black Hills
 Tuesday/Wednesday.
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&&

.DISCUSSION...
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(This Evening Through Friday)
Issued at 144 PM MDT Fri May 3 2024

Cold upper low across southern Canada continues to lift out of
the region this afternoon. Southern periphery impulse along the
stalled baroclinic zone has supported rain/snow across the
southeast half today and will continue to shift ESE with the
associated FGEN area. Expect rain to develop and shift SE across
scentral SD this afternoon and taper off by evening. Skies will
clear out across most places tonight with dry air spreading into
the region. This will allow for a cool night with lows in the
20s/30s and some teens in the Black Hills. Warmer and dry Sat with
highs generally in the 60s. Strong western CONUS upper trough
will then shift east into the Rockies and support pressure falls
over the region Sun. This will force increasing SE winds, becoming
quite breezy by afternoon across the NW SD plains where adv winds
are likely. Pos theta-e adv with a weakening cap may allow for a
thunderstorm or two over NE WY in the afternoon. However, better
chances for more widespread rains will arrive Sunday night with
the main moisture surge and WAA. Strong storm system will then
move onto the plains Monday, with the sfc trough/dryline shifting
east across southwest through scentral SD. Current progs suggest
that the severe threat will remain south and east of the FA, but
if things slow down some, there may be a small window for severe
weather across far scentral SD. Further west, deformation rains
will spread into the region along with gusty NW winds. Adv to low
end warning winds will be possible Monday across much of western
SD, with the bulk of wind in NW SD. However, rains may limit
mixing and gust potentials. As the upper low stalls and then
slowly migrates east, winds, rain, and cool weather will persist
through Wed night. Rain will change to snow in the higher
elevations of the Black Hills Monday night with some light accums
possible. However, the better chance for snow accums looks to be
Tue night into Wed when colder air advects into the region. Things
will begin to slowly warm up and dry out toward next weekend as
the upper low finally exits the region.
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&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1113 AM MDT Fri May 3 2024

MVFR/local IFR conditions will persist across the Black Hills and
adjacent plains, through mid afternoon with light rain and snow.
Areas of MVFR conditions will persist through mid afternoon mainly
across the SD plains east of the Black Hills to KPHP and KD07.
VFR conditions will continue elsewhere. Conditions over the Black
Hills area and plains to the east will gradually improve to VFR
by late afternoon and early this evening.

&&

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

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...15