679  
FXUS63 KUNR 230517  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
1017 PM MST THU FEB 22 2018  
   
DISCUSSION
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 247 PM MST THU FEB 22 2018  
 
DEEP UPPER TROUGH IS PERSISTING ACROSS THE WESTERN CONUS, WITH  
SOUTHWESTERLY FLOW OVER THE CENTRAL ROCKIES THROUGH THE NORTHERN  
PLAINS AND UPPER MIDWEST. BROAD SURFACE LOW PRESSURE IS DEEPENING  
ACROSS THE CENTRAL PLAINS INTO CENTRAL SOUTH DAKOTA. KUDX RADAR  
SHOWS SNOW MOVING INTO CENTRAL SOUTH DAKOTA OVER THE LAST FEW HOURS.  
SNOW WILL CONTINUE TO FALL TONIGHT MAINLY OVER SOUTH CENTRAL SD  
WHERE ANYWHERE FROM 1 TO 4 INCHES OF ACCUMULATION ARE EXPECTED. IT  
STILL LOOKS LIKE THE HIGHER SNOWFALL AMOUNTS WILL BE LIMITED TO  
TRIPP COUNTY. WILL CONTINUE WITH THE WINTER WEATHER ADVISORY FOR  
TRIPP UNTIL 9 PM CST. SNOW WILL QUICKLY END BY MID TO LATE EVENING.  
LOWS TONIGHT WILL DROP TO AROUND 5 BELOW TO 10 ABOVE ZERO. SURFACE  
HIGH PRESSURE AND WEAK UPPER RIDGING WILL BUILD IN FOR FRIDAY. DRY  
WEATHER IS EXPECTED WITH HIGHS SIMILAR TO TODAY. THE WESTERN UPPER  
TROUGH WILL SLIDE EASTWARD SATURDAY WITH A SURFACE LOW STRENGTHENING  
NEAR KANSAS/NEBRASKA. WRAP AROUND PRECIP WILL MOVE INTO THE REGION,  
BUT MOSTLY STAY SOUTH AND EAST OF THE CWA. SOUTH CENTRAL SOUTH  
DAKOTA WILL LIKELY SEE ANOTHER ROUND OF ACCUMULATING SNOW. RIGHT NOW  
IT APPEARS TO BE ANOTHER 1 TO 3 INCHES TOTAL LATE FRIDAY NIGHT INTO  
SATURDAY. GENERALLY DRY WEATHER IS THEN EXPECTED THROUGH SUNDAY AND  
MONDAY. HIGHS WILL BE IN THE UPPER 20S INTO THE 30S. RIGHT NOW  
MODELS ARE INDICATING SOME LIGHT SNOW POSSIBLE TUESDAY OR WEDNESDAY  
AS A SHORTWAVE TROUGH PUSHES THROUGH.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 1017 PM MST THU FEB 22 2018  
 
IN THE WAKE OF THIS EVENING'S LIGHT SNOW, MVFR/IFR CIGS HAVE  
DEVELOPED ACROSS PORTIONS OF THE SD PLAINS, PARTICULARLY ALONG AND  
EAST OF A LINE FROM KD07 TO KIEN. THESE ARE EXPECTED TO DRIFT  
SOUTHEASTWARD OUT OF OUR AREA BY 10Z, ALLOWING VFR CONDITIONS TO  
PREVAIL AREA-WIDE THROUGH FRIDAY AFTERNOON.  
 
CONDITIONS WILL BEGIN TO DETERIORATE FROM SOUTH TO NORTH ACROSS  
EASTERN WY/WESTERN NE LATE IN THE TAF PERIOD AS SNOW OVERSPREADS  
THE REGION. ASSOCIATED LOWERED CIGS/VSBYS COULD REACH THE SOUTHERN  
BLACK HILLS, AND POTENTIALLY EVEN APPROACH OUR TAF SITES, BY 06Z  
TOMORROW EVENING. FOR NOW, HOWEVER, EXPECTING VFR CONDITIONS TO  
PREVAIL THROUGH THE TAF PERIOD AT KRAP/KGCC.  
 

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

 
 

 
 
DISCUSSION...13  
AVIATION...SHERBURN  
 
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