Rapid Valley, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

059
FXUS63 KUNR 012344
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
544 PM MDT Sun Jun 1 2025

.KEY MESSAGES...

- There is a marginal (level 1 of 5) risk over portions of
  northeastern WY this afternoon and evening. Main threats will be
  large hail and damaging winds.

- There is a marginal (level 1 of 5) to slight (level 2 of 5) risk
  over south central SD for Monday afternoon and evening. Main
  threats will be large hail and damaging winds.

- Unsettled weather continues through next week with daily chances
  for showers and storms.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 155 PM MDT Sun Jun 1 2025

WV imagery depicts upper level ridge over the Northern Plains
with a deepening trough over western Canada/the PNW. Sfc analysis
shows the a sfc front/trough draped across southeastern MT. 18z
KUNR sounding depicts 1300 J/kg SB CAPE within a strongly capped
and dry environment. Visible satellite imagery shows clear skies
over the CWA with clouds/convection beginning to form off of the
Big Horns. The instability and increasing shear will contribute
to a marginal (level 1 of 5) severe threat over northeastern WY
late this afternoon and evening. However, with the lack of
moisture and main source of lift coming through after dark,
confidence in severe weather occurring this afternoon and evening
remains very low. Most recent CAMs show a line of convection
developing by 02-03z with a few isolated storms forming ahead of
the line. If strong to severe storms manage to form, the main
threats will be hail (1+" diameter) and damaging winds (60+ mph
gusts).

The main cold front will push through the CWA overnight and will
have mostly passed through the CWA by Monday afternoon. Therefore,
while we may see a few thunderstorms in the morning with the sfc
cold front and then later in the afternoon as the upper level
front moves through, it`s unlikely we`ll see anything too
widespread or severe for much of the CWA. However, further east
towards south central SD, the front will be moving through during
the afternoon hours. There`s a marginal (level 1 of 5) to slight
(level 2 of 5) severe risk across portions of far south central SD
and along the SD/NE border as moderate instability (MU CAPE of
1000-1500 J/kg per NAM) develops ahead of the front. The strongest
shear remains displaced from the best instability, so a
widespread severe threat isn`t anticipated at this time. Stronger
storms will be capable of hail (1+" diameter) and damaging winds
(60+ mph gusts).

Northwest winds will also pick up Monday behind the front,
supported by 3 hr pressure rises of 2-4 mb, 30-40 kt 850-700 mb
winds, and modest CAA. HREF guidance has been conservative on wind
probs with low (0-20%) chances for gusts to exceed 45 mph. The
NBM does have medium (40-60%) probs for 45 mph gusts, mainly over
the western SD south of I-90 on Monday afternoon and evening.
Therefore, will not issue any headlines.

As we enter the mid-to-late week, quasi-zonal and active flow
develops over the central US. In terms of sensible weather
impacts it will mean moderating temperatures (highs will be in
the 60s to 70s) with periodic chances for showers and storms.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 540 PM MDT Sun Jun 1 2025

Scattered storms will cross northeastern WY and western SD
this evening and again on Monday, as a cold front crosses the
region. MVFR CIGS will move into NE WY late tonight, then western
SD on Monday behind the front. IFR conditions will be possible
across the higher Black Hills. Gusty NW/N winds are also expected
late tonight and Monday.

&&

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

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...13