484
FXUS63 KUNR 270444
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1044 PM MDT Sun Jul 26 2026

.KEY MESSAGES...

- Hot weather will continue this week with highs in the 90s.

- Thunderstorms will be possible at times this week. Main threat
  with storms will be gusty winds.

&&

.UPDATE...
Issued at 1026 PM MDT Sun Jul 26 2026

KUDX radar shows a line of storms stretching from just east of
Hulett to Upton through south central Weston County. Surface obs
are showing 40-55 kt winds with this line. These storms/strong
winds are expected to subside over the next hour or two as they
cross the Black Hills. A few of the latest CAMs are showing
isolated elevated storms overnight, but believe most locations
will stay dry through sunrise. Suface obs are also showing a cool
front crossing Tilford toward Elm Springs and along the Cheyenne
River Valley. NE surface winds behind the front are drawing in
smoke from MT/ND (originally from the Northern Rockies region).
Smoke is expected to linger mainly across NW/Central SD through
Monday. Temps will once again be hot on Monday, but slightly
cooler than Sunday. Apparent temps don`t make it to advisory
criteria, so at this point will not be reissuing any heat-related
headlines. CAMs are in agreement that a shortwave now over UT will
push into the CWA late Monday. MLCAPE will be in the 500-1000
J/kg range across NE WY into the Black Hills. It increases to 2500
J/kg over the western to central SD plains where dewpoints will
be around 60F. Storms are expected to initiate over the Bighorns
to NE WY in the early afternoon where CIN is very weak.
Outflows/upper forcing will then propogate toward the Black Hills
and western SD plains through the mid afternoon to early evening
hours, allowing for futher convective development as it overcomes
the cap. Shear is weak over NE WY but is moderate over western SD,
so could see some strong to severe storms east of the Black
Hills. Though, with the dry boundary layer, can`t rule out strong
wind gusts from storms over NE WY, either. With the incoming
monsoonal moisture, GFS shows PWATs at 150-175% of normal, so some
storms could have heavy rain.

&&

.DISCUSSION...(This Afternoon Through Saturday)
Issued at 1154 AM MDT Sun Jul 26 2026

Upper level ridge will remain anchored over the Rockies into the
Plains supporting hot temperatures through this week. The FA will
remain on the northern periphery of the ridge with impulses
traversing the flow. This will support near daily chances for TS
as monsoon waves traverse the region. Week sfc trough has advected
through the FA today with winds shifting northerly. This has
knocked temps down a few degrees from yesterday, but still very
hot. Weak capping over the BH with sufficient moisture will allow
a few shra/ts to develop there this afternoon. Main focus will be
the next impulse expected to support TS this evening in the west.
TS will develop across WY and push east into the western FA this
evening. High based nature will support gusty winds as the storms
push east. As the wave progresses through the FA overnight, sct-
isold shra/ts will be possible, mainly across the north. Hot
Monday with temps in the mid to upper 90s once again. The next
wave will arrive late afternoon/early evening and support TS
across the western half, possibly earlier over the BH if
subsidence behind tonight`s wave has pushed east. Again, gusty
winds will be the main threat from TS given continued high based
nature. Same for each day the rest of the week, daily chances for
shra/TS as monsoon moisture continues to advect around the
backside of the ridge. Most days will see isold-sct activity given
lack of strong forcing and high based nature of storms. However,
a stronger wave may bring slightly better coverage of storms Wed
into Thur if timing works out right. Otherwise, a break in this
pattern and heat is not expected until early next week with a
stronger northern stream shortwave flattens the ridge and supports
a decent cold front into the Northern Plains.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Monday Night)
Issued At 1039 PM MDT Sun Jul 26 2026

A line of showers/thunderstorms along the WY/SD border will
continue to move east and slowly dissipate through 09Z. There
could be some gusty and erratic winds up to 45kts associated with
some of the storms before they dissipate. Wildfire smoke will
continue to drift south into the region today, mainly impacting
northwestern SD and the central SD plains. More thunderstorms are
expected to develop across northeast WY around 22Z and move into
western SD during the late afternoon and early evening hours.
Gusty and erratic winds will once again be the main threat with
the thunderstorms. Even with all of this, VFR conditions are
expected through the valid forecast period.



&&

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

$$

UPDATE...13
DISCUSSION...JC
AVIATION...Hintz