FXUS63 KUNR 071137

AFDUNR



Area Forecast Discussion For Western SD and Northeastern WY

National Weather Service Rapid City SD

537 AM MDT Thu May 7 2026



.KEY MESSAGES...



- Warming trend as we move towards and through the weekend.



- Active northwest flow will bring chances for showers and

  thunderstorms today, and again on Saturday; severe weather is

  generally not expected at this time.



- Much warmer next week with increasing fire weather concerns due

  to increased winds and lower relative humidities.



&&



.UPDATE...

Issued at 942 PM MDT Wed May 6 2026



Minor changes to the previous forecast. Storm track has shifted 

south some in forecast models for both Thur and Sat impulses. This

has resulted in a SW shift in the higher pops, most noticeable in

western SD. Dropped highs a couple degrees Thur and esp Fri as the

cool front moves through faster. Still on track for a sig warm up

next week with 80s and few 90s possible early next week. All else

on track.



&&



.DISCUSSION...(This Evening Through Wednesday)

Issued at 1213 PM MDT Wed May 6 2026



Current Water Vapor and upper air models show northwest flow over

the FA, as weak troughing sits over the Great Lakes region and

upper ridge builds over the far western CONUS. 18Z Surface

analysis has high pressure centered over eastern Wyoming this

afternoon. Satellite shows some low-top CU development over the

forecast area. Temperatures currently sit in the 40s and low 50s

over the region, with winds out of the northwest. 



Upper ridge builds over the Rockies tonight and Thursday,

resulting in warmer temperatures for the area. Highs Thursday will

be in the upper 50s and 60s, while Friday will see widespread 70s.

Main concern for Thursday will be the potential for showers/storms

as a shortwave rides the northwest flow through the CWA.  

The better forcing region for precipitation potential looks to be

from northeastern WY into the Black Hills and southwestern SD. Low

CAPE values (200-400 j/Kg) and some low eff shear will be enough

to spark some thunderstorms in the showery regions. Given the 

forecast thermal profiles, not expecting any severe storm 

potential, but some gusty winds 40-50mph may be possible near 

showers/storms. 



Dry conditions return Friday, but precipitation chances return

Saturday as a weak wave moves thorugh WY into SD/NE. Upper ridge

slides over the Rockies into the northern and central plains early

next week, resulting in continued warmer temperatures and mostly

dry conditions Sunday through middle of next week. 



&&



.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)

Issued At 537 AM MDT Thu May 7 2026



Scattered rain showers and isolated t-storms are expected to 

cross the region today, starting in northeastern Wyoming after 

15z/9am. Based on the latest high-res guidance, confidence in 

shower activity is increasing for KGCC, and have thus added 

predominant -SHRA while refining the timing on the PROB30 for 

-TSRA. Brief periods of MVFR cigs/vsbys will be possible under 

heavier showers and storms today, especially across northeastern 

Wyoming, the Black Hills, and far southwestern South Dakota, in an

otherwise solidly VFR environment throughout the TAF period. A 

few storms may produce small hail and erratic wind gusts of 

35-40kts. Further east...confidence in coverage of showers/storms 

remains lower at KRAP and have continued a PROB30 with refined 

timing. Precip chances decrease quickly north and east of KRAP 

into the South Dakota plains.



&&



.UNR WATCHES/WARNINGS/ADVISORIES...

SD...None.

WY...None.



&&



$$



UPDATE...JC

DISCUSSION/KEY MESSAGES...Dye/KSmith

AVIATION...KSmith