639
FXUS63 KUNR 241055
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
455 AM MDT Fri May 24 2024

.KEY MESSAGES...

- Gusty winds subside later today
- Relatively active pattern expected through Memorial Day weekend
- Upper level ridge brings milder and drier weather mid-week next
  week

&&

.DISCUSSION...(Today Through Thursday)
Issued at 117 AM MDT Fri May 24 2024

07z surface analysis showed low near KMBG with cold front into
central NE and trough into southeast MT. Upper low spinning over
K2WX per water vapour with compact deformation zone blob of
precipitation rotating through far northeast WY/northwest SD per
regional radar loop. Synoptic winds starting to pick up over
western SD as pressure rises increase behind surface trough. Main
concern in the short term is wind.

Today, upper/surface low moves northeast. Most guidance depicts
3-6mb/3hr pressure rises bubbling through western SD this morning.
Boundary layer winds increase to 35-50kts with probabilistic
guidance showing 60%+ chance of 40kt+ wind gusts with 30-60%
chance of 48kt+ wind gusts in the squeeze area just east of the
Black Hills. Even though wind gust speeds have lollygagged early
this morning, current headlines still look reasonable. Should be
able to drop southwest SD later this morning, assessing the state
of northwest SD per observations around the same time.
Precipitation shield quickly moves northeast of the CWA with
subsidence bringing clearing skies today. Temperatures will be
near guidance.

Tonight, pleasantly cool weather foreseen. Saturday, shortwave
slides east/southeast across the area bringing a chance of
showers/TS. Buoyancy/shear profiles not supportive of organized
active storms. Better-defined shortwave/upper-low zips through the
area for Saturday night through Sunday night with robust PoPs
warranted. Not sure the entire period will be a washout, but most
folks should get some QPF (25-50% >0.25"). Upper ridge pops up
late Monday through most of next week resulting in mild/mostly dry
weather per probabilistic/ensemble guidance.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 449 AM MDT Fri May 24 2024

Area of MVFR conditions over northwestern into central SD
associated with -RA will exit the region from west to east through
this morning with the forecast area clear of precip by around
14-15z. VFR conditions can then be expected areawide through the
rest of the forecast period.

Gusty northwest winds are expected across much of the western
South Dakota plains through the morning hours and will then
gradually decrease through the afternoon. Widespread gusts of 40
to 45 kts are expected. Gusts of up to 50kts are possible over the
plains adjacent to the eastern Black Hills, which includes KRAP.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 2 PM MDT this afternoon for SDZ001-002-012-
     013-026-078.
     Wind Advisory until 3 PM MDT this afternoon for SDZ014-032-043.
     Wind Advisory until 6 AM MDT early this morning for SDZ027-041-
     075-076.
     High Wind Warning until 2 PM MDT this afternoon for SDZ031-072-
     073.
     Wind Advisory until 5 PM MDT /6 PM CDT/ this afternoon for
     SDZ044-046-047-049-077.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Wong