165  
FXUS63 KUNR 202126  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
226 PM MST TUE FEB 20 2018  
   
DISCUSSION
 
(THIS EVENING THROUGH TUESDAY)  
ISSUED AT 226 PM MST TUE FEB 20 2018  
 
UPPER TROUGH IS CENTERED ACROSS THE WESTERN HALF OF THE CONUS WITH  
SURFACE HIGH PRESSURE CROSSING THE DAKOTAS. SKIES HAVE BECOME  
MOSTLY SUNNY ASIDE FROM SOME LIGHT SMOKE OVER SOME PORTIONS OF THE  
CWA. CLEAR SKIES WILL CONTINUE TONIGHT WITH TEMPS DROPPING TO WELL  
BELOW FREEZING ONCE AGAIN. SOUTHERLY FLOW WILL SET UP OVERNIGHT AS  
HIGH PRESSURE SLIDES EAST OF THE REGION. WINDS COMBINED WITH COLD  
TEMPS WILL RESULT IN WIND CHILLS OF 20 BELOW TO 30 BELOW ZERO.  
WIND CHILL ADVISORY HAS BEEN ISSUED FOR ALL AREAS EXCEPT THE SD  
BLACK HILLS WHERE TEMPS WILL BE WARMER, BUT STILL BELOW ZERO.  
UPPER TROUGH WILL PERSIST OVER THE WESTERN CONUS AND INTENSIFY  
THURSDAY AS A STRONG SHORTWAVE DROPS DOWN THE PACIFIC COAST. A  
SERIES OF SHORTWAVES WILL EJECT OUT ACROSS THE CENTRAL PLAINS  
BRINGING SNOW TO NEBRASKA AND EASTERN SOUTH DAKOTA. AT THIS TIME  
IT APPEARS THE SNOW WILL GRAZE SOUTH CENTRAL SOUTH DAKOTA THURSDAY  
AFTERNOON/EVENING. HOWEVER, SNOWFALL TOTALS WILL BE LIMITED TO AN  
INCH OR SO. GRADUALLY WARMER TEMPS ARE EXPECTED EACH DAY THROUGH  
THE SECOND HALF OF THE WEEK, REACHING THE MID 30S IN SOME  
LOCATIONS BY SATURDAY OR SUNDAY. DRY WEATHER IS EXPECTED ACROSS  
THE CWA AS THE MAIN ACTIVE FLOW REMAINS TO THE SOUTH/EAST.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)  
ISSUED AT 1020 AM MST TUE FEB 20 2018  
 
VFR CONDITIONS WITH MOSTLY CLEAR SKIES WILL CONTINUE THROUGH  
AVIATION FORECAST PERIOD.  
 

 
   
UNR WATCHES/WARNINGS/ADVISORIES
 
 
SD...WIND CHILL ADVISORY FROM 6 PM MST /7 PM CST/ THIS EVENING TO 9  
AM MST /10 AM CST/ WEDNESDAY FOR SDZ001-002-012>014-025>027-  
030>032-041>044-046-047-049-072>074.  
 
WY...WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 9 AM MST WEDNESDAY  
FOR WYZ054>058-071.  
 

 
 

 
 
DISCUSSION...13  
AVIATION...10  
 
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