313
FXUS63 KUNR 310848
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
248 AM MDT Fri May 31 2024

.KEY MESSAGES...

- Cooler and showery weather for much of the area today.

- Warmer over the weekend with daily chances for showers and
  thunderstorms. Some storms could be strong to severe.

- Warm weather expected for much of next week with drier conditions
  mid to late week.

&&

.DISCUSSION...(Today Through Thursday)
Issued at 248 AM MDT Fri May 31 2024

Current surface analysis shows cold front just south and east of
the forecast area, with weak high pressure over WY. Upper level
analysis shows low over south central Canada, with trough
extending southward into the northern and central Plains. Weak
disturbance moving through the area is bringing showers to
portions of northeast WY and western SD. Temps are cool, mostly
40s and lower 50s, with light west to northwest winds.

Near zonal flow aloft over the next several days will keep the
weather unsettled at times as embedded weak disturbances cross the
region. Current shower activity will persist through the morning
hours, mainly from the Black Hills area into southwest and south
central SD, with activity starting to taper off during the midday
and afternoon. There could be some thunder later this morning into
the afternoon, but forecast CAPE is minimal today across our area.
Highs will stay on the cooler side today, 60s and lower 70s, with
some 50s across the higher Black Hills. Another cooler night
expected with lows mostly in the 40s early Saturday. A few
showers/storms could clip far southern SD late tonight as modest
Theta-e advection develops over NE.

Warm advection aloft starts to take place later tonight and
especially on Saturday as trough shifts east-northeast of the
region. Saturday will see highs in the 70s to near 80 degrees, with
80s to the south and east of the Black Hills on Sunday. Developing
south to southeast winds will bring increasing low level moisture
into most of the area, especially east of the Black Hills. Main
chances for a few storms later on Saturday look to be southeast of
the Black Hills and especially into south central SD as surface trof
sets up over the central high Plains and low level jet intensifies
further to the east. MUCAPE values of 1000 to 2000 j/kg toward south
central SD and moderate shear will increase potential for strong to
marginally severe storms with hail and gusty winds. The better
chances for more widespread showers and storms should be on Sunday
as a cold front approaches the area. Timing of the front and
associated energy aloft with determine where and when any stronger
storms could develop, which is still uncertain right now. However,
the better chances for stronger storms right now would look to be
east of the Black Hills and especially toward central SD.

Outlook for much of next week is still for seasonably mild to warm
conditions. Upper level pattern during the first half of the week is
more uncertain, with many ensemble solutions showing a shortwave
trough crossing the northern Plains/south central Canada late Monday
into Tuesday. Better chances for showers and storms would generally
be from northeast WY to northwest SD during this time. Majority of
model solutions have a building ridge over the western US and large
trough covering the eastern US mid to late week. This would bring
above average temperatures, 70s and 80s for highs most days, and
mostly dry conditions for this time.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Friday Night)
Issued At 1038 PM MDT Thu May 30 2024

Showers and isolated thunderstorms will continue to develop
through the nighttime hours across portions of northeastern WY
and western SD. This may result MVFR conditions, mainly near the
Black Hills through Friday morning. Then drier air will return
after 18z Friday, with VFR conditions again expected.

&&

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

$$

DISCUSSION/KEY MESSAGES...26
AVIATION...13