129  
FXUS63 KUNR 161719  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
1119 AM MDT THU AUG 16 2018  
   
DISCUSSION
 
(TODAY THROUGH WEDNESDAY)  
ISSUED AT 403 AM MDT THU AUG 16 2018  
 
CURRENT UPPER LEVEL ANALYSIS HAS COMPACT CLOSED LOW OVER SOUTHEAST  
SOUTH DAKOTA WITH LARGE RIDGE BUILDING ACROSS THE NORTHERN  
ROCKIES. SKIES ARE MOSTLY CLEAR ACROSS NORTHEAST WYOMING AND  
WESTERN SOUTH DAKOTA, WITH SOME LINGERING CLOUDS ACROSS FAR SOUTH  
CENTRAL SOUTH DAKOTA. AT THE SURFACE, HIGH PRESSURE IS LOCATED  
ACROSS MONTANA, WYOMING, AND THE DAKOTAS. WINDS ARE LIGHT, AND  
TEMPERATURES AT 4 AM ARE IN THE 50S TO LOWER 60S.  
 
UPPER RIDGE WILL SLOWLY SHIFT ACROSS THE NORTHERN PLAINS TODAY AND  
FRIDAY. DRY CONDITIONS AND NEAR AVERAGE TEMPERATURES ARE EXPECTED.  
 
A PROGRESSIVE UPPER TROF WILL MOVE ACROSS THE NORTHERN PLAINS FOR  
THE WEEKEND. MOISTURE RETURN BEGINS IN EARNEST FRIDAY NIGHT AS  
BOUNDARY LAYER WINDS BECOME SOUTHERLY AHEAD OF THE SYSTEM. AS THE  
SURFACE TROF AND MID LEVEL LOW SHIFTS INTO WESTERN SD MID DAY  
SATURDAY, CAPE VALUES OF 1500-2500 J/KG AND MODEST SHEAR SHOULD  
PRODUCE SOME STRONG TO SEVERE STORMS ACROSS THE SOUTH DAKOTA  
PLAINS THROUGH EARLY EVENING. RAIN AND ISOLATED THUNDERSTORMS WILL  
PERSIST INTO SUNDAY MORNING BEFORE SHIFTING EAST OF THE AREA  
SUNDAY AFTERNOON AND EVENING.  
 
EARLY NEXT WEEK, WEST TO NORTHWEST FLOW MAY BRING SOME LOW  
CHANCES OF PRECIPITATION AT TIMES, BUT MOSTLY DRY CONDITIONS  
SHOULD PREVAIL. THE WEEK WILL START OFF WITH SLIGHTLY BELOW  
AVERAGE TEMPERATURES, AND WARM TO NEAR AVERAGE BY MID WEEK.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)  
ISSUED AT 1118 AM MDT THU AUG 16 2018  
 
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.  
 

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

 
 

 
 
DISCUSSION...15  
AVIATION...HELGESON  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SD Page
The Nexlab WY Page Main Text Page