Lead, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

784
FXUS63 KUNR 231835
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1235 PM MDT Tue Jun 23 2026

.KEY MESSAGES...

- Increasingly active convective pattern will develop this week
  and persist through the upcoming weekend
- Isolated severe thunderstorms possible Wednesday
  afternoon/evening in the far southwest
- Slight risk of severe thunderstorms Thursday afternoon/evening,
  especially west
- Saturday could be quite active, but confidence in position of
  frontal boundaries and upper support/thermal ridge on the low
  side

&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 1233 PM MDT Tue Jun 23 2026

18z surface analysis had cold front well south/east of the CWA
with weak high from MT into western SD. Diurnal heating fluffing
some CU here and there per 0.5km visible satellite loop, but
atmosphere is short on fuel per 18z KUDX sounding. Better looking
south of the CWA. Water vapour loop had upper low over south
central Canada supporting west/northwest flow aloft over the
northern Plains.

Through tonight, some shra/TS may develop, but best buoyancy
south of CWA so not expecting organized convection. Lows tonight
will be near guidance.

Wednesday, shortwave moves across MT/Dakotas during peak heating
with plenty of shear, but only 500-1000J/kg mean MUCAPE across the
far southwest. Isolated severe thunderstorms may occur with the
latest CAMS indicating strongest updraft/helicity tracks south of
the CWA. Temperatures will remain on the cool side given forecast
lower tropospheric soundings.

Thursday looks more interesting as deep upper low/trough drops
into southwest Canada/northwest CONUS turning our upper flow
west/southwest. Lee trough develops with robust southeasterly
return flow over the CWA bringing richer boundary moisture.
Barring significant stratus development (guidance/pattern hints
this will occur), combination of buoyancy/shear across the western
half of the area will be sufficient for a slight risk of severe
thunderstorms.

Friday, upper low deepens over the northwest CONUS with southwest
flow aloft developing, but with height rises over the northern
Plains which may help to suppress organized convection. If
something goes, active storms will occur. Saturday/Sunday, upper
low ejects northeast with a favorable setup for active/severe
thunderstorms each day. Of course, details way too far out to get
into, but subjective pattern recognition suggests a busy weekend.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1111 AM MDT Tue Jun 23 2026

Transient MVFR ceilings will continue across portions of NE WY,
the Black Hills, and south-central SD through 20z this afternoon.
Otherwise, VFR conditions are expected with broken ceilings around
5000-10000 feet AGL. Isolated showers/storms are possible this
afternoon across the Black Hills.

&&

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

$$

DISCUSSION...Helgeson
AVIATION...SE