142  
FXUS63 KFSD 181725  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
1125 AM CST SAT NOV 18 2017  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 311 AM CST SAT NOV 18 2017  
 
POSITIVELY TILTED TROUGH SWINGING THROUGH THE REGION THIS MORNING  
WILL EXIT TO THE EAST BY MIDDAY TODAY. LIGHT ASSOCIATED RAINFALL  
ALONG THE 700 MB FRONTOGENETIC BAND CONTINUE TO WEAKEN AS IT EXITS  
THE FORECAST AREA BY DAYBREAK. BEHIND THIS SYSTEM, DRIER AIR WILL  
BEGIN WORKING INTO THE REGION FROM WEST TO EAST, ALLOWING SKIES TO  
QUICKLY CLEAR. STRONG PRESSURE GRADIENT AND INCREASED LOW/MID LEVEL  
NORTHWEST WINDS MIXING DOWN WILL BRING A RETURN TO BREEZY  
CONDITIONS. BY MIDDAY, WINDS WILL AVERAGE 15 TO 30 MPH WITH GUSTS TO  
35 MPH. DESPITE THE SUNNIER SKIES, TEMPERATURES WILL NOT BUDGE MUCH,  
AND THE GUSTY WINDS WILL MAKE CONDITIONS FEEL EVEN COLDER. HIGHS ARE  
EXPECTED IN THE MID 30S TO MID 40S.  
 
SURFACE HIGH PRESSURE EXPANDS ACROSS THE NORTHERN PLAINS THIS  
EVENING INTO TONIGHT. SKIES WILL BE CLEAR OR MOSTLY CLEAR, WITH  
WINDS QUICKLY DROPPING BELOW 10 MPH IN THE EVENING. THIS WILL LEAD  
TO COOLER NIGHTTIME LOWS, IN THE UPPER TEENS TO MID 20S. NUDGED  
TOWARDS THE COLDER CONMOS TEMPERATURES FOR LOWS.  
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 311 AM CST SAT NOV 18 2017  
 
A MAINLY DRY PATTERN WITH UPS AND DOWNS IN TEMPERATURE IS THE MAIN  
FEATURE ON THE EXTENDED.  
 
THE WORK WEEK WILL START OFF ON THE WARM SIDE AS NORTHWESTERLY WINDS  
SHIFT TO THE SOUTH-SOUTHWEST AS AN UPPER RIDGE BUILDS ACROSS THE  
HIGH PLAINS THROUGH MONDAY. HIGHS ON SUNDAY WILL BE IN THE 40S WHILE  
HIGHS ON MONDAY COULD BE A FEW DEGREES WARMER. TEMPERATURES ON  
MONDAY WILL BE 10 TO 15 DEGREES ABOVE NORMAL.  
 
FAST-MOVING UPPER WAVES WILL CONTINUE TO MOVE ALONG THE NORTHERN  
PLAINS AND THE INTERNATIONAL BORDER KEEPING THE REGION UNDER A ZONAL  
TO NORTHWESTERLY FLOW PATTERN FOR THE BEGINNING OF NEXT WEEK THROUGH  
WEDNESDAY. A COLD FRONT DRIFTS SOUTHWARD FROM THE NORTHERN PLAINS  
MONDAY EVENING THROUGH TUESDAY BRINGING BRISK NORTHWESTERLY WINDS  
AND A CHANGE IN TEMPERATURES. LITTLE TO NO PRECIPITATION IS  
ANTICIPATED BY THE PROXIMITY OF THIS FRONT DUE TO A LACK OF MOISTURE  
TRANSPORT OR SOURCE OVER THE REGION. WITH NORTHWESTERLY FLOW  
PREVAILING ON TUESDAY, DRIER AND COOLER AIR WILL KEEP TEMPERATURES 5  
TO 10 DEGREES BELOW NORMAL. GIVEN MOSTLY CLEAR SKIES AND LIGHT  
WINDS, MODEL GUIDANCE SUGGESTS A COOL NIGHT WITH LOWS DROPPING IN  
THE TEENS BY WEDNESDAY MORNING.  
 
FLOW PATTERN CHANGES BY THE MIDDLE OF THE WEEK AS MODELS PROG A  
SURFACE HIGH OVER THE PLAINS, BRINGING BACK MILDER TEMPERATURES TO  
THE REGION. THE OUTLOOK FOR THANKSGIVING HASN'T CHANGED MUCH  
COMPARED TO PREVIOUS RUN. AT THIS POINT, IT LOOKS GENERALLY QUIET  
WITH WARMER THAN NORMAL TEMPERATURES, BEING FRIDAY A COUPLE OF  
DEGREES WARMER. HIGHS COULD REACH THE UPPER 50S BY FRIDAY.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)  
ISSUED AT 1122 AM CST SAT NOV 18 2017  
 
GUSTY NORTHWEST WINDS, UP TO 35 MPH AT TIMES, WILL PERSIST  
THROUGH THE AFTERNOON HOURS AND WILL BE THE MAIN CONCERN DURING  
THIS TAF PERIOD. ADDITIONALLY, THE REMNANTS OF AN MVFR STRATUS  
FIELD CONTINUE TO DISSIPATE AS IT APPROACHES KFSD WITH A FEW  
CUMULUS HERE AND THERE. OVERALL, VFR CONDITIONS ARE EXPECTED  
THROUGH THE PERIOD.  
 

 
   
FSD WATCHES/WARNINGS/ADVISORIES
 
 
SD...NONE.  
MN...NONE.  
IA...NONE.  
NE...NONE.  

 
 

 
 
SHORT TERM...  
LONG TERM...05  
AVIATION...KALIN  
 
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