956
FXUS63 KUNR 031707
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1107 AM MDT Thu Jul 3 2025

.KEY MESSAGES...

- Hot with chances for isolated storms this afternoon. A few
  storms in northwestern South Dakota may become strong to severe
  with large hail and damaging winds as the main concerns.

- Scattered thunderstorms likely on Friday. Severe weather isn`t
  expected, though stronger storms could produce heavy rainfall
  and small hail.

- Average to above average temperatures and chances for storms
  will continue through the next week.

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 308 AM MDT Thu Jul 3 2025

Showers and storms are ongoing across northeastern WY into
western SD. While a few updrafts have pulsed up and produced small
hail and gusty winds, not expecting severe storms to develop from
this activity. The storms have also kicked off a few gusty
outflow boundaries which are visible on radar reflectivity and
velocity products. Sfc stations are reporting gusts of 30-50 mph
associated with the ofb passage. Upper level ridge axis sits over
the Northern Plains with a weak upper level disturbance cresting
the ridge over MT/ND. The upper ridge will begin to shift east
today with a low level thermal ridge developing across the
Northern Plains. Afternoon temperatures will climb into the 90s
across the CWA with spots along the western SD plains hitting the
triple digit mark. Bulk of moisture transport and therefore the
corridor of highest buoyancy will remain to the east and north of
the CWA, which will limit overall convective potential this
afternoon. Increasing height falls and Q-vector convergence ahead
of a shortwave will support increasing chances for convection
across northeastern WY, the Black Hills, and northwestern SD later
this afternoon and evening. Modest bulk shear values of 30 to
40kt could support rotating updrafts and a marginal severe threat.
Deep, well mixed boundary layers and steep low to mid level lapse
rates will support damaging wind gusts and large hail with any
severe storms that develop.

Shortwave crosses the region Friday, bringing chances for
scattered thunderstorms across much of the CWA. Temperatures will
cool off slightly, with highs ranging from the mid 70s across the
Black Hills and northeastern WY to the upper 80s and low 90s
across western SD. With weak CAPE (generally below 1000 J/kg per
HREF probs) and modest shear (30-40kt), severe potential should be
low for Friday. PWAT values of 150-175% of normal will support
heavy rainfall with storms on Friday.

Westerly, zonal upper flow will develop across the northern tier
of the US by the weekend. Periodic disturbances moving along the
flow will bring chances for thunderstorms through this weekend
into next week. Temperatures will remain seasonable with highs in
the 80s to 90s.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1105 AM MDT Thu Jul 3 2025

VFR conditions expected to prevail through most of the period for
most areas. Scattered -TSRA will develop this afternoon and
evening, mainly over northeastern WY/far western SD. Gusty
southerly winds will continue across the western SD plains this
afternoon before shifting to the northwest tonight as a cold front
moves through the area.

&&

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

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...Smith