FXUS63 KUNR 242319

AFDUNR



Area Forecast Discussion For Western SD and Northeastern WY

National Weather Service Rapid City SD

519 PM MDT Fri Oct 24 2025



.KEY MESSAGES...



- Above normal temperatures expected for the weekend



- Elevated fire weather conditions expected as well for the 

  weekend



- Cooler and unsettled weather moving in Sunday night through 

  Monday



&&



.DISCUSSION...(This Evening Through Friday)

Issued at 133 PM MDT Fri Oct 24 2025



Latest water vapor imagery shows 500 hpa wave dropping into 

northeast ND/northwest MN with a few clouds impacting northeast 

SD/western MN. Another larger closed 500hpa low in the vcnty of 

4-corners slowly drifting to the south & east. 500Hpa ridge 

extends from southern CA through central MT ahead of strong 

longwave trough pushing onshore across the western CONUS. At the 

surface, high pressure is firmly in control across the CWA with 

generally light winds and a few high thin clouds dotting the sky. 

Temps around 18Z are a few degrees either side of 60 degrees F. 



First detail to keep track of is the stratus deck that is lifting 

northward out of NE and into SC/SE South Dakota. If this deck 

moves into our far southeastern counties, it could keep the 

overnight lows up a category or two, and keep them down a category

for Saturday. The HRRR 850hpa RH values show this cloud deck 

staying just east of Tripp county for now, but it will be close 

for sure. 



Next concern will be potential fire weather issues for Saturday 

and Sunday. Lee troughing sets up during the day Saturday, 

increasing the surface wind speeds across the CWA. 850Hpa temps 

across the west are 16-18C...setting up for highs well above the 

seasonal norm. Across our WY counties and the SD plains ensemble 

mean RH values fall to around 20% with mean sfc winds from 15 to 

20 mph. On Sunday as the 500hpa ridge slides east and SW flow 

develops aloft, sfc pre-frontal trough moves through aiding in 

keeping breezy/windy conditions in place. High temperatures will 

probably be a little cooler when compared to Saturday, but the 

elevated fire weather conditions look to persist across the far 

southwestern counties where RH values still remain AOA 20% with 

the winds. 



Last concern deals with pcpn probabilities Sunday night into 

Monday as main cold front pushes through. Models are showing 

fairly strong winds behind the fropa with 3-4mb pressure rises on 

the backside, plus good CAA as seen at 850hpa and downsloping on 

the 700hpa theta-e surface. Feel that pcpn will first start off as

-shra along and ahead of cold fropa Sunday evening/early night 

but will transition over to -sn (especially over the hills and NW 

SD) during the overnight hours. There is some concern that even 

the foothills/near plains could see some flakes of snow Monday 

morning. Of interest was that the GFS was actually showing advry 

criteria snowfall by Monday afternoon across our far NW counties. 



After Monday, weak upper level ridging will move back into the

area bringing drier and seasonable conditions to the area through

mid-week when another system is progged to drop through Thursday. 



&&



.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)

Issued At 516 PM MDT Fri Oct 24 2025



VFR conditions will prevail across the area through the TAF 

period. Skies remain mostly clear with the occasional high level 

cirrus. Breezy southerly winds can be expected Saturday.



&&



.FIRE WEATHER...

Issued At 133 PM MDT Fri Oct 24 2025



Elevated fire weather conditions will be in place Saturday across 

northeast Wyoming, into the Black Hills and the western SD plains.

Highs will climb into the low to mid 70s with relative humidities

falling to around 20 percent. Winds will be southerly from 10 to 

20 mph with gusts to near 30 mph at times. 



Elevated fire weather conditions will return for Sunday, mainly

across the Weston County plains into far southwestern SD.

Afternoon relative humidities will again be around 20 percent with

afternoon highs around 70. South winds at 15 to 20 mph will switch

to the west as a dry front moves through during the afternoon

hours. 



&&



.UNR WATCHES/WARNINGS/ADVISORIES...

SD...None.

WY...None.

&&



$$



DISCUSSION/KEY MESSAGES...Hintz

AVIATION...JC

FIRE WEATHER...Hintz