FXUS63 KUNR 231740

AFDUNR



Area Forecast Discussion For Western SD and Northeastern WY

National Weather Service Rapid City SD

1140 AM MDT Thu Apr 23 2026



.KEY MESSAGES...



- Cool and breezy unsettled weather expected Thursday through the

  weekend.



&&



.UPDATE...

Issued at 727 PM MDT Wed Apr 22 2026



01z surface analysis had robust low over the MT/ND/Canadian border

with a warm front into IL and an impressive dry-line/trough into

western NE. It has been the focus for high-based convection this

evening per 0.5-1KJ/kg MLCAPE and 1500J/kg DCAPE. Result has been

a mix of convective/non-convective wind reports, with the highest

focus on outflow boundaries where severe thunderstorm warnings 

were issued. Expect additional convection this evening over south-

central SD per CAMS/dry-line/trough interaction. Further west 

over the higher terrain, deep boundary layer mixing resulting in 

frequent wind gusts around 45kts with a few locally higher 

reports. The last few hours of the 0.5km visible satellite imagery

has been interesting with terrain effects. HRRR has been

persistent in an uptick in winds over the Black Hills this

evening, so will keep an eye on them. Forecast has been updated 

to account for these features.



Looking ahead to Thursday, latest guidance suggests a period of 

high winds over northwestern SD per gradient/daytime mixing. 

Latest NBM guidance gives 50-80% chance of 50kt gusts for K2WX- 

KRCA. Left Rapid City out given the significant westerly 

component to the wind direction. Hoisted a Wind Advisory just to 

the east of the warning and also put one out for far southwestern 

SD per current/expected wind gusts this evening and then Thursday.

Some rain/snow showers will wrap into northeastern 

WY/northwestern SD by Thursday morning as parent upper low spins 

into ND with backwash moisture.



Jury is still out on stripe of potential QPF/snow Thursday night 

and Friday as another shortwave rotates around the upper low so 

will continue with highest PoPs across the southwestern half of 

the CWA.



Finally, will let the Red Flag Warning expire at 8pm. Conditions

will very slowly improve tonight.



&&



.DISCUSSION...(This Evening Through Wednesday)

Issued at 101 PM MDT Wed Apr 22 2026



Plenty of weather to talk about today that's for sure. For

starters, a quick look at the calendar is a good way to remind 

yourself that it's not June or July but April! Afternoon temps

have soared well beyond the normal for late April and have reached

the 80s and 90s, which is near 25 to 30 degrees above normal.

Strong southerly winds, with gusts upwards of 40 to 50 mph, have

helped to usher in that warmer air. To add to this, very low

humidities, down to near 10%, means we are seeing critical fire

weather conditions around the area. These conditions will last

through the early evening. Then temps will cool, humidity will

recover, and winds will relax.



The next part of the forecast we are focusing on is the potential

for strong to severe thunderstorms later this afternoon and

evening. A boundary is tracking through the upper plains and

strong to severe storms are possible along that boundary. The

main concern for the mode of severe weather is wind gusts. The

area of concern for where the storms could pop up is pretty much

the all of western SD but higher confidence in the central part of

the state, so stay plugged into the weather through the evening 

for the latest.



Late tonight and Thursday brings a passing cold front, that will 

swing winds to the west and increase them, again, to gusts upwards

of 40 to 50 mph. These westerly winds will usher in cooler air, 

so expect daily highs to drop to the 40s and 50s. Overnight lows 

will dip into the 20s to low 30s. Temps like this are below normal

for this time of year.



Friday and beyond, the northwest flow will keep an active pattern

in place so we are looking at on/off rain or showers to linger in

the forecast. And with cold temps at night, any precip we see 

could fall as a rain/snow mix, or all snow, during the cold times

of the day. The higher elevations of the Black Hills have a high 

chance of seeing accumulating snow Saturday night. Stay plugged 

into the forecast over the coming days for the details.



&&



.AVIATION...(For the 18Z TAFS Through 18Z Friday)

Issued At 1139 AM MDT Thu Apr 23 2026



A cold front will continue to move through the region with gusty northwest

winds behind it, light rain and snow showers, and areas 

MVFR/local IFR conditions across northeastern WY/northwestern SD. 

Wind gusts over 50 knots will be possible across NW SD. Another 

disturbance will bring a chance of rain/snow to the area tonight, 

with more MVFR (local IFR) conditions.



&&



.UNR WATCHES/WARNINGS/ADVISORIES...

SD...High Wind Warning until 6 PM MDT this evening for SDZ001-002-012-

     013-031-072-073-078.

     Wind Advisory until 6 PM MDT this evening for SDZ014-027-032-041-

     075.

WY...None.

&&



$$



UPDATE...Helgeson

DISCUSSION/KEY MESSAGES...GSmith

AVIATION...Schultz