212  
FXUS63 KUNR 211443  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
843 AM MDT SUN JUL 21 2024  
   
KEY MESSAGES
 
 
- HAZY SKIES AND ISOLATED THUNDERSTORMS TODAY AND MONDAY.  
 
- HOT AND DRY FOR THE LAST HALF OF THE WEEK WITH ELEVATED/CRITICAL  
FIRE WEATHER CONDITIONS.  
 

 
   
UPDATE
 
 
ISSUED AT 841 AM MDT SUN JUL 21 2024  
 
12Z KUNR SOUNDING SUPPORTS ELEVATED CONVECTION, WHICH CAN BE SEEN  
AS SOME ACCAS/ISOLATED TS OVER SOUTH-CENTRAL SD. A SMALL  
-TSRA CLUSTER HEADING OUR WAY FROM NORTH-CENTRAL SD. IN ADDITION,  
LATEST CAMS SUGGESTS ISOLATED CONVECTION POSSIBLE OVER FAR WESTERN  
PORTIONS OF THE CWA. POPS MASSAGED TO ADDRESS.  
 

 
   
DISCUSSION
 
(TODAY THROUGH SATURDAY)  
ISSUED AT 220 AM MDT SUN JUL 21 2024  
 
CURRENT SURFACE MAP PLACES WEAK HIGH ACROSS THE NORTHERN PLAINS.  
WATER VAPOR SHOWS UPPER RIDGE ACROSS THE INTERMOUNTAIN WEST  
NORTHWARD INTO THE CANADIAN ROCKIES WITH SEVERAL WEAK IMPULSES  
DROPPING THROUGH THE AREA. A BIT OF ACCAS IS AROUND THE BLACK  
HILLS/SOUTHWEST SOUTH DAKOTA WITH AN ISOLATED THUNDERSTORM NEAR  
NEWCASTLE. ISOLATED THUNDERSTORMS MAY POP UP THROUGH EARLY  
MORNING.  
 
FOR TODAY AND MONDAY, NORTH/NORTHWEST FLOW ALOFT CONTINUES.  
THICK SMOKE LAYER ALOFT FROM CANADIAN FIRES WILL KEEP HAZE  
AROUND. ISOLATED THUNDERSTORMS POSSIBLE WITH EACH PASSING  
ATMOSPHERIC WIGGLE. WEAK BUOYANCY/SHEAR WILL LIMIT SEVERE THREAT.  
 
UPPER LEVEL RIDGE SHIFTS EASTWARD TUESDAY AND WEDNESDAY WITH LOW  
LEVEL THERMAL RIDGE SPILLING INTO THE NORTH PLAINS. TEMPERATURES  
PEAK THURSDAY/FRIDAY WITH 50-70% PROBABILITY OF HIGHS >=100F FOR  
NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA PLAINS. "COLD" FRONT  
WILL BRING SLIGHTLY COOLER TEMPERATURES FOR THE WEEKEND.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 523 AM MDT SUN JUL 21 2024  
 
VFR CONDITIONS ARE GENERALLY EXPECTED TODAY INTO TONIGHT.  
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED  
ACROSS MUCH OF THE AREA TODAY. MOSTLY FROM AROUND MIDDAY INTO THE  
EVENING HOURS. BRIEF MVFR CONDITIONS AND GUSTY WINDS ARE POSSIBLE  
NEAR ANY STORMS.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 220 AM MDT SUN JUL 21 2024  
 
AN UPPER LEVEL RIDGE WILL BRING HOT AND DRY CONDITIONS TUESDAY  
INTO FRIDAY. AS THE UPPER RIDGE BREAKS DOWN FRIDAY, A COLD FRONT  
WILL SLIP INTO THE AREA. THERE IS CONSIDERABLE UNCERTAINTY WITH  
THE COLD FRONT TIMING. THE PRE-FRONTAL ENVIRONMENT WILL SEE  
TEMPERATURES IN THE 90S TO AROUND 100 AND VERY LOW RELATIVE  
HUMIDITY. LREF IS GIVING 70-90% PROBABILITY OF RELATIVE HUMIDITY  
LOWER THAN 15% ACROSS NORTHEASTERN WYOMING AND FAR WESTERN SOUTH  
DAKOTA THURSDAY AFTERNOON. THE PATTERN ALSO FAVORS SOME WINDY  
AREAS WHICH WOULD RESULT IN CRITICAL FIRE WEATHER CONDITIONS  
THURSDAY FOR PARTS OF THE AREA. ELEVATED/NEAR CRITICAL FIRE  
WEATHER CONDITIONS ARE EXPECTED FRIDAY, WITH THE HIGHER WINDS  
MAINLY EAST OF THE BLACK HILLS.  
 

 
   
UNR WATCHES/WARNINGS/ADVISORIES
 
 
SD...NONE.  
WY...NONE.  

 
 

 
 
UPDATE...HELGESON  
DISCUSSION/KEY MESSAGES...7  
AVIATION...26  
FIRE WEATHER...7  
 
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