Fairpoint, South Dakota Weather Forecast Discussion

103
FXUS63 KUNR 182012
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
212 PM MDT Thu Sep 18 2025
.KEY MESSAGES...
- Precipitation ends Friday morning with some fog overnight
- Drier and warmer for the weekend
- Low confidence forecast next week
&&
.DISCUSSION...(This Evening Through Thursday)
Issued at 203 PM MDT Thu Sep 18 2025
19z surface analysis had low over central SD with upper low
stacked above it per water vapour loop. Weakening showers
continue rotating around it with some weak diurnal showers popping
up over western SD per shallow buoyancy (18z KUNR sounding). Some
cumulus further west with water vapour showing the next wave of
interest over eastern MT.
Tonight/Friday morning, central SD shifts east/northeast
(precipitation in the east wanes) as eastern MT shortwave spins
through the CWA. MT shortwave moisture will be limited, but most
guidance (including CAMs) suggest a band of showers will drop
through the western half of the CWA overnight. Very weak MUCAPE,
but enough for a few lightning strikes. Recent moisture and
converging T/Td spreads later tonight/Friday morning suggest
patchy/areas of fog will develop. Showers/clouds could suppress
extent, but plenty of potential to leave in the forecast.
Temperatures will be near guidance.
Upper/thermal ridge builds into the northern plains later Friday
into the weekend with drier/warmer conditions expected.
Low confidence forecast next week. LREF mean flow suggests an
open wave moves through early in the week with upper ridge
thereafter. However, some ensemble guidance has a significant
upper low moving across the plains with the CWA on the northern
periphery which would create big changes to the NBM forecast. Stay
tuned.
&&
.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1121 AM MDT Thu Sep 18 2025
MVFR/IFR conditions with rain will continue into the afternoon
across central and south-central SD. Conditions will continue to
slowly improve from west to east today with conds trending VFR to
MVFR (MVFR cigs may linger through the day in central SD). MVFR
to IFR conds are possible again early Friday in patchy fog and low
clouds, mainly across the western SD plains. In addition, there
is a chance of showers across the southwest third late tonight
into Friday morning as a wave pushes through.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...SE

NWS UNR Office Area Forecast Discussion