-- Discussion containing changed information from previous version are highlighted. --
169
FXUS63 KUNR 112317
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
517 PM MDT Tue Jun 11 2024

.KEY MESSAGES...

- Near to above average temperatures through Thursday with a few
  late day/nighttime showers and thunderstorms possible.

- A more unsettled pattern returns Friday, with daily chances for
  storms into early next week.

&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 306 PM MDT Tue Jun 11 2024

Current surface analysis shows a cool front well east of the
region, with south to southwest winds developing and bringing
warmer air into the area. Upper level analysis shows low pressure
over south central Canada, with associated trough to the south
extending into the upper midwest. West to northwest flow is in
place from the Rockies into the Plains, with weak ridging from the
northern Rockies to the Great Basin. Current temps are mostly in
the upper 70s to mid 80s, with 70s over the Black Hills, under
mostly sunny skies.

Warmer conditions will continue to build across the region through
Wednesday as the shortwave ridge moves east across the region. Highs
will reach the 80s across most of the area Wednesday, with some
lower 90s to the southeast of the Black Hills into south central SD.
Isolated showers and thunderstorms could develop tonight, especially
later tonight across northwest SD, as a subtle disturbance aloft
interacts with developing low level jet and increasing mid-level
theta-e advection across western SD. Any thunderstorms that develop
through midweek should be on the weaker side, with activity mainly
at night/early morning and MUCAPE values remaining on the low side,
generally 500 j/kg or less. Another weak cold front will cross the
area on Wednesday, bringing breezy northwest winds. With a lack of
energy and forcing aloft associated with the front, it should pass
through our area dry. However, a few showers and storms could
develop Wednesday night, mainly east of the Black Hills, as another
very weak disturbance passes over the area. Thursday will be a bit
cooler, but still near or slightly above average, with highs in the
mid 70s to lower 80s. Again, a few late day or nighttime showers and
storms could develop over parts of the area as low level southerly
jet develops over the central/northern high Plains. Chances could
linger into Friday morning over at least eastern portions of the
forecast area.

Another shortwave ridge is progged to pass quickly over the area
Friday, with above average temperatures, especially over northeast
WY into far western SD. The pattern aloft will change for the
weekend into early next week as a trough likely develops over the
Pacific NW and southwesterly flow extends eastward across the
Rockies into the Plains. Embedded disturbances in the flow will
bring chances for thunderstorms at times starting later Friday and
continuing through at least the weekend. Increasing moisture and
CAPE should bring better potential for strong to severe storms
Friday PM, and possibly on Saturday as well as a cold front and
stronger shortwave trough approach the region. Timing of
disturbances looks more uncertain for the second half of the weekend
into early next week, but Sunday looks to be the nicer weekend day
at this point. Another shortwave could move across the northern
Rockies into the northern Plains by early next week, with additional
chances for showers and storms. There is a high likelihood (above 70
percent) of temps dropping off to below average levels by Monday,
with highs mostly in the upper 60s and 70s early next week.

&&

.AVIATION...
-- Changed Discussion --
(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 514 PM MDT Tue Jun 11 2024

Isolated showers are possible after 06z tonight mainly across
northwestern and central SD. Otherwise, VFR conditions are
expected through the TAF period.
-- End Changed Discussion --


&&

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

$$

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