FXUS63 KUNR 070507

AFDUNR



Area Forecast Discussion For Western SD and Northeastern WY

National Weather Service Rapid City SD

1107 PM MDT Sun Apr 6 2025



.KEY MESSAGES...



- Lower visibilities due to fog possible Monday morning along the

  eastern Foothills of the Black Hills and adjacent plains.



- Marginal risk of strong storms Tuesday afternoon across parts of

  northeast Wyoming and across the Black Hills area.



- Elevated fire weather conditions return across the western SD

  plains on Wednesday.



&&



.DISCUSSION...(This Evening Through Sunday)

Issued at 144 PM MDT Sun Apr 6 2025



20Z upper level analysis has sharp ridge to the west, and trof to

the east, leading to fast northerly flow over the Northern 

Plains. Skies are mostly clear. At the surface, strong backdoor

cold front is located across North Dakota. South of the front

across the forecast area, winds are out of the northwest, with 

temperatures in the 50s.



Backdoor cold front will continue to drop south into the area

overnight. Model soundings suggest as Monday morning approaches, 

stratus deck develops over the western SD plains, and shifts into 

the Black Hills area by 12Z. Western edge of stratus should be low

enough that areas of fog develop along the eastern edge of the

Black Hills and adjacent plains, persisting into late morning.

Brisk northeast to east flow will keep temperatures cool through

the morning, and moderating into the 40s and 50s by mid afternoon

as stratus and fog dissipate. Mostly sunny conditions expected

further west, with highs in the 50s and 60s.



Upper ridge shifts into the Northern Plains Monday night into

Tuesday, with dry conditions and above average temperatures

expected. Late Tuesday, upper trof crosses Montana, and

atmospheric profiles become favorable for some showers and

isolated thunderstorms to develop across northeast WY and far

western SD. Marginal shear and CAPE profiles may produce a

stronger storm or two, with up to quarter sized hail possible.

Some locations could see a tenth to a quarter inch of rainfall

from these storms. 



Active northwest flow continues into Wednesday, with additional

chances for rain showers persisting through Wednesday night. 

Surface low pressure and associated trof shift east of the CWA on 

Wednesday, with surface high pressure sliding into the Northern 

Rockies. This will produce a tight pressure gradient across the 

western SD plains, where wind gusts to 40 mph will be likely. With

mild temps and afternoon RHs around 25%, elevated fire weather 

conditions will be possible across the SD plains Wednesday 

afternoon.



Upper level ridge re-establishes itself across the Northern Plains

Thursday into the weekend, bringing mainly dry conditions and 

above average temperatures. Elevated fire weather conditions

could persist into Thursday afternoon as northerly winds remain 

quite gusty.



&&



.AVIATION...(For the 06Z TAFS Through 06Z Monday Night)

Issued At 1106 PM MDT Sun Apr 6 2025



Mainly VFR conditions will prevail through the TAF period. Some

low stratus/patchy fog may develop across parts of the western SD

plains early Monday morning, as a cold front backs into the

region. Fog is no longer expected at KRAP.



&&



.UNR WATCHES/WARNINGS/ADVISORIES...

SD...None.

WY...None.

&&



$$



DISCUSSION/KEY MESSAGES...15

AVIATION...Pojorlie