792  
FXUS63 KUNR 111057  
AFDUNR  
 
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY  
NATIONAL WEATHER SERVICE RAPID CITY SD  
357 AM MST MON DEC 11 2017  
   
DISCUSSION
 
(TODAY THROUGH SUNDAY)  
ISSUED AT 241 AM MST MON DEC 11 2017  
 
WATER VAPOR IMAGERY DEPICTS A STRONG CIRCULATION ASSOCIATED WITH  
THE UPPER WAVE MOVING THROUGH THE DAKOTAS. A 120 KT JET IS DIVING  
SOUTH WITH THE WAVE, OVER MT, NORTHEASTERN WY, AND WESTERN SD.  
MID/HIGH CLOUDS ARE STREAMING INTO THE AREA WITH THE JET, AND AN  
AREA OF LOWER CEILINGS IS ALSO PUSHING INTO SD FROM WESTERN ND.  
NORTHWESTERLY WINDS ARE GUSTY ACROSS THE WESTERN SD PLAINS,  
ESPECIALLY JUST EAST OF THE BLACK HILLS, WHERE SUSTAINED WINDS ARE  
ALREADY 30-40 MPH. TEMPERATURES AT 2 AM RANGE FROM THE 30S ACROSS  
LESS WINDY NORTHEASTERN WY, TO THE 40S AND 50S ACROSS THE WESTERN  
SD PLAINS.  
 
FORECAST SOUNDINGS FOR HRRR, RAP, NAM, AND GFS CONTINUE TO SHOW VERY  
STRONG WINDS MIXING DOWN EARLY THIS MORNING, ESPECIALLY EAST OF THE  
BLACK HILLS. NAM IS STILL SHOWING A 5-6 MB PRESSURE DIFFERENCE  
ACROSS THE HILLS THROUGH 15Z THIS MORNING. SUSTAINED WINDS OF 40+  
MPH WITH GUSTS OF 60+ MPH ARE EXPECTED FOR THE PLAINS EAST OF THE  
HILLS, SO HAVE ISSUED A HIGH WIND WARNING. HAVE ALSO EXPANDED THE  
WIND ADVISORY TO INCLUDE THE SOUTHEASTERN FOOTHILLS AND MUCH OF  
SOUTHERN SD. WINDS ACROSS NORTHWESTERN SD MAY REACH WARNING CRITERIA  
AT TIMES, BUT FOR THE MOST PART EXPECTING A HIGH-END WIND ADVISORY  
EVENT. THE STRONGEST WINDS FOR NORTHWESTERN SD AND AREAS JUST EAST  
OF THE BLACK HILLS WILL BE THIS MORNING, AND GRADUALLY DIMINISH  
THROUGH THE AFTERNOON. AREAS FARTHER SOUTH WILL BE GUSTIEST DURING  
THE MIDDLE OF THE DAY. WIND-ADVISORY-CRITERIA WINDS WILL BE POSSIBLE  
ACROSS SOME LOCATIONS UNTIL 00Z, SO ALL HEADLINES END THEN.  
 
SOUTH CENTRAL SD MAY SEE SOME LIGHT RAIN/SNOW TODAY WITH THE PASSING  
WAVE, BUT MOST OF THE PRECIP WILL STAY TO THE EAST. HIGHS TODAY WILL  
BE GENERALLY IN THE 40S.  
 
WARM AIR WILL MOVE INTO THE AREA TUESDAY, AHEAD OF THE NEXT WAVE.  
HIGHS WILL WARM BACK INTO THE 50S. THE ECMWF AND GFS ARE IN BETTER  
AGREEMENT ABOUT THE TRACK AND TIMING OF THE TUESDAY NIGHT/WEDNESDAY  
WAVE, ALTHOUGH THE ECMWF IS A BIT STRONGER. NAM IS SHOWING ANOTHER  
TIGHT PRESSURE GRADIENT OVER THE BLACK HILLS EARLY WEDNESDAY, SO  
MORE DOWNSLOPING WIND WILL BE POSSIBLE. GUSTY NORTHWEST WINDS ARE  
EXPECTED ACROSS THE SD PLAINS ON WEDNESDAY AS WELL, AND HIGHS WILL  
BE IN THE 40S. A REINFORCING SHOT OF COLDER AIR AND CONTINUED BREEZY  
WINDS ARE EXPECTED FOR THURSDAY WITH ANOTHER PASSING SHORTWAVE.  
UPPER RIDGING AND A WARM FRONT WILL BRING ANOTHER MILD DAY FRIDAY,  
BUT CHANCES FOR PRECIPITATION INCREASE FOR THE WEEKEND AS A STRONGER  
WAVE PUSHES THROUGH.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)  
ISSUED AT 355 AM MST MON DEC 11 2017  
 
MVFR CIGS WILL AFFECT AREAS ALONG/EAST OF A LINE FROM K2WX-KVTN  
THROUGH 21Z WITH VFR CONDITIONS THEREAFTER. ELSEWHERE, VFR  
CONDITIONS WILL PERSIST THROUGH THE PERIOD. GUSTY NORTHWEST WINDS  
ARE EXPECTED TODAY WITH GUSTS AROUND 40KTS ON THE PLAINS OF  
WESTERN SD. LOCAL GUSTS AROUND 50KTS EXPECTED NEAR KRAP THROUGH  
18Z.  
 

 
   
UNR WATCHES/WARNINGS/ADVISORIES
 
 
SD...WIND ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON FOR  
SDZ001-002-012>014-025-030-032-042>044-046-047-049-074.  
 
HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR SDZ026-031-  
072-073.  
 
WY...NONE.  

 
 

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

The Nexlab SD Page
The Nexlab WY Page Main Text Page