260  
FXUS63 KUNR 221723  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
1123 AM MDT MON JUL 22 2019  
   
DISCUSSION
 
(TODAY THROUGH SUNDAY)  
ISSUED AT 205 AM MDT MON JUL 22 2019  
 
WATER VAPOR SHOWS UPPER RIDGE BUILDING INTO THE NORTHERN ROCKIES  
WITH LARGE SCALE SUBSIDENCE/DRY AIR OVER THE NORTHERN PLAINS.  
SURFACE HIGH IS LOCATED OVER THE WESTERN DAKOTAS. A BIT OF LOW  
CLOUDS ATTEMPTING TO WORK NORTH INTO OUR FAR SOUTHWESTERN ZONES  
IN RETURN FLOW ON BACKSIDE OF HIGH. VERY PLEASANT TEMPS EARLY THIS  
MORNING IN THE 50S, WITH SOME 40S IN THE BLACK HILLS.  
 
DRY AND PLEASANT CONDITIONS EXPECTED TODAY WITH LARGE SCALE  
SUBSIDENCE IN PLACE. TEMPS WILL WARM INTO THE 70S TO LOWER 80S. ON  
TUESDAY, A BIT MORE RETURN FLOW EXPECTED WITH HIGHS WELL INTO THE  
80S AS THERMAL RIDGE NUDGES EASTWARD INTO EASTERN WYOMING. CAPE  
WILL INCREASE BUT LARGE SCALE SUBSIDENCE SHOULD LIMIT ANY  
THUNDERSTORM DEVELOPMENT TO THE HIGHER TERRAIN OF THE BLACK HILLS.  
 
UPPER RIDGE BEGINS TO BREAK DOWN ON WEDNESDAY AS UPPER TROF WORKS  
THROUGH THE NORTHERN ROCKIES. FORCING ALONG COLD FRONT WITH  
COOLING TEMPS ALOFT WILL LEAD TO THUNDERSTORM DEVELOPMENT IN OUR  
WESTERN ZONES IN THE AFTERNOON, WITH CHANCES EXTENDING ONTO THE SD  
PLAINS WEDNESDAY NIGHT. SUFFICIENT CAPE WITH MODEST SHEAR WILL  
LEAD TO A CHANCE FOR SOME SEVERE STORMS. WEDNESDAY WILL LIKELY BE  
THE HOTTEST DAY OF THE WEEK WITH HIGHS INTO THE 90S FOR MOST  
PLAINS LOCATIONS AHEAD OF THE COLD FRONT.  
 
MOSTLY ZONAL FLOW EXPECTED THROUGH THE DURATION OF THE EXTENDED  
WITH IMPULSES IN THE FLOW BRINGING CHANCES FOR STORMS AT TIMES,  
ALTHOUGH THERE DOESN'T APPEAR TO BE A LOT OF MOISTURE TO WORK  
WITH. TEMPS SHOULD BE CLOSE IF NOT A FEW DEGREES ABOVE AVERAGE  
THROUGH THE WEEKEND.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)  
ISSUED AT 1120 AM MDT MON JUL 22 2019  
 
VFR CONDITIONS ARE EXPECTED THROUGH TUESDAY MORNING.  
SOUTHEASTERLY WINDS WILL BE BREEZY ACROSS NORTHWESTERN SD TODAY.  
 

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

 
 

 
 
DISCUSSION...JOHNSON  
AVIATION...15  
 
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