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129
FXUS63 KUNR 130443
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1043 PM MDT Wed Jun 12 2024

.KEY MESSAGES...

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

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

&&

.DISCUSSION...(This Evening Through Wednesday)
Issued at 246 PM MDT Wed Jun 12 2024

Current surface analysis shows a cool front from far northwest MN
to eastern SD to northern NE. Upper level analysis shows near
zonal flow from the Pacific NW into the northern high Plains.
Skies are mainly sunny with warm temps ranging from the upper 70s
to lower 90s, warmest toward south central SD. Breezy
northwesterly winds linger across mainly northwest SD this
afternoon.

Relatively quiet weather expected through Thursday as high pressure
passes over the northern Rockies and northern Plains. A weak
embedded disturbance in the zonal flow could bring some high based
showers/thundershowers late tonight/early Thursday to areas mainly
northeast and east of the Black Hills. Slightly cooler air behind
the front to the east will result in lows tonight in the upper 40s
and 50s, with highs on Thursday in the mid 70s to mid 80s. Lighter
north to northwest winds can be expected into Thursday, with winds
generally switching to the south and southeast by later Thursday
night as the high shifts east of the region. Low level southerly jet
develops later Thursday night across the northern/central high
Plains, with modest theta-e advection as well across most of the
area. This should result in an increase in shower and thunderstorm
chances late Thursday night into Friday morning, especially across
southwest to central SD. An isolated strong storm or two is
possible.

Weather pattern will become more unsettled from Friday into early
next week as upper trough moves into the Pacific NW and a series of
disturbances move from the northern Rockies to the northern Plains.
Shortwave ridge will track over the area on Friday, with above
average highs in the 80s to near 90 degrees, warmest over northeast
WY. Developing southwesterly flow aloft later Friday into Friday
night will bring energy across WY and into the Dakotas. Southerly
flow will bring increasing moisture and resultant MLCAPE values of
1000 to 2000 j/kg across much of western SD later in the day, with
the more favorable shear likely from northwest into central SD. At
least a marginal risk for severe storms is expected for most of the
area Friday afternoon and evening, with large hail and strong wind
gusts the main threats from any stronger storms. There looks to be
some lingering potential for stronger storms later Saturday into
Saturday night, especially across far northeast WY into northwest
SD, along and ahead of an approaching cold front and upper level
shortwave. Timing of the front and exact track of the shortwave will
likely play a role in how much of a threat there will be, as right
now the front is forecast to pass during the evening into the
overnight hours. Sunday will be mainly dry and breezy with more
seasonable temps. Persistent southwesterly flow aloft will likely
bring more chances for storms Sunday night and early next week as
another stronger shortwave is progged to pass through the Pacific NW
trough. Forecast for the middle and latter parts of next week is
much more uncertain, but could at least see a break in chances for a
portion of the midweek period. Temps for most of next week look to
be relatively close to seasonal averages, highs in the 70s to
low/mid 80s.

&&

.AVIATION...
-- Changed Discussion --
(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1042 PM MDT Wed Jun 12 2024

Isolated to scattered showers and thunderstorms will be possible
until around 12z, mainly across northwest 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