AFOS product AFDUNR
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Displaying AFOS PIL: AFDUNR
Product Timestamp: 2025-09-25 17:18 UTC

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709 
FXUS63 KUNR 251718
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1118 AM MDT Thu Sep 25 2025

.KEY MESSAGES...

- Dry conditions and above average temperatures into next week
- Gusty northerly winds behind cool front Friday
- Elevated fire weather conditions at times

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 1256 AM MDT Thu Sep 25 2025

06z surface analysis had weak trough from northern ND into MT. 
Water vapour loop showed upper ridge over Rockies poking into the 
northern Plains with upper trough approaching BC. Plenty of stars 
across the CWA per nighttime physics RGB. BC upper trough the main
forecast concern.

Today/tonight, weak trough brushes the CWA with the main effect 
being wind shifts. Thermal ridge will support highs in the 80s on
the plains with 70s for the Black Hills. Went a skosh above 
guidance per abundant solar insolation/dry air.

Friday, upper ridge flattens courtesy of BC upper trough zipping 
across the northern plains. 2-4mb/3hr pressure rises behind 
advancing dry cool front will combine with well-mixed boundary 
layer (25-35kt mean per Bufkit soundings) to produce gusty winds 
at times. A few spots may gust near 40mph (20% chance HREF/NBM). 
Temperatures will be slightly above guidance again given dry air, 
especially ahead of the cool front over southern SD.

Saturday through early next week, upper ridge becomes 
reestablished over the plains as it shifts east in response to 
upper trough developing over the northwest CONUS. Eventually, 
southwest flow aloft develops over the northern plains, but 
moisture will be scant until possibly the end of next week when 
low pops appear. Temperatures will be 5-12F above normal on 
average.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1116 AM MDT Thu Sep 25 2025

VFR conditions are expected through the forecast period. Winds 
will generally be variable at RAP until a cold front moves through
towards the end of the period. At GCC, winds are expected to 
shift from southerly this evening to northerly as the 
aformentioned cold front move through tomorrow morning.

&&

.FIRE WEATHER...
Issued At 1256 AM MDT Thu Sep 25 2025

Sustained dry weather with above normal temperatures will bring 
elevated fire weather conditions to the area over the next 7 days.
MinRH will drop to the teens over northeastern WY this afternoon 
and over northeastern WY/southwestern SD Friday. MinRH in the 20s 
will be common elsewhere through the forecast period. Breezy winds
will occur at times, but particularly Friday with a dry cool 
front passage may bring wind gusts near 40mph on the northwest SD
plains.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Bunker
FIRE WEATHER...Helgeson