965  
FXUS63 KFSD 202326  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
526 PM CST MON NOV 20 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY)  
ISSUED AT 330 PM CST MON NOV 20 2017  
 
MOSTLY UNEVENTFUL SHORT TERM FORECAST. UPPER TROUGH WILL SWING  
THROUGH THE MB/ON/MN BORDER REGION THIS EVENING, FOCUSING ANY  
FORCING STRONG ENOUGH TO PRODUCE PRECIPITATION FAR TO OUR NORTH.  
ONLY IMPACT HERE WILL BE THE PASSAGE OF THE SURFACE COLD FRONT AND  
THE GUSTY NORTHWEST WINDS THAT WILL ARRIVE IN ITS WAKE. WITH  
CLEARING SKIES AND STRONG COLD ADVECTION, EXPECT LOWS TO DROP INTO  
THE 20S FOR MOST OF THE CWA WITH WIND CHILLS AS LOW AS 10.  
 
THE GUSTY NORTHWESTERLY WINDS WILL CONTINUE THROUGH TUESDAY.  
EXPECTING SOME OF THE SUSTAINED WINDS AND A POTENTIALLY A COUPLE  
GUSTS TO HIT WIND ADVISORY CRITERIA IN SOUTHWEST MINNESOTA SO HAVE  
ISSUED A WIND ADVISORY. BECAUSE OF THE STRONG COLD ADVECTION,  
DESPITE THE MOSTLY CLEAR SKIES, TEMPERATURES WILL STRUGGLE TO GET  
ABOVE 30 THROUGH THE DAY TUESDAY.  
   
LONG TERM
 
(TUESDAY NIGHT THROUGH MONDAY)  
ISSUED AT 330 PM CST MON NOV 20 2017  
 
PRESSURE GRADIENT AND WITH IT THE WINDS FINALLY LET UP TUESDAY NIGHT  
AS HIGH PRESSURE BUILDS IN OVERHEAD. LUCKILY, ALL THE MIXING FROM  
THE PRECEDING GUSTY PERIODS WILL LEAVE US WITH REDUCED SURFACE  
MOISTURE AND SCANT FOG POTENTIAL EVEN WITH WINDS CLOSE TO CALM.  
 
AMPLIFIED UPPER PATTERN OFF THE PACIFIC COAST ONCE AGAIN SPURS BROAD  
LEE TROUGHING ACROSS THE WESTERN PORTION OF THE NORTHERN PLAINS.  
THIS WILL INDUCE A RETURN OF GUSTY SOUTHERLY WINDS AND SOME MID  
LEVEL CLOUDS TO THE REGION WEDNESDAY. THE MID LEVEL CLOUDS ALONG  
WITH A QUASI-STATIONARY BOUNDARY WILL HELP KEEP HIGHS DOWN ACROSS  
SOUTHWEST MN AND NORTHWEST IA DOWN WHILE SOUTH CENTRAL SD COULD MIX  
OUT INTO THE MID 50S. HAVE BOOSTED HIGHS A BIT IN SOUTH CENTRAL SD  
IN DEFERENCE TO THE IMPRESSIVE WARM LAYER ALOFT.  
 
QUASI-STATIONARY BOUNDARY HANGS AROUND FOR THANKSGIVING. ANOTHER  
LITTLE PUSH OF MID LEVEL CLOUDS IN THE AFTERNOON WILL ONCE AGAIN  
REINFORCE THE GRADIENT ACROSS THE CWA. HAVE AGAIN BOOSTED HIGHS FOR  
THE SAME REASON AS WEDNESDAY. WITH LESS OF A PRESSURE GRADIENT  
ACROSS THE REGION, WILL STICK WITH CONSENSUS WINDS. NO FOUL WEATHER  
ANTICIPATED.  
 
PACIFIC NW TROUGH FINALLY BREAKS DOWN A BIT AND TRANSLATES ENERGY  
ACROSS THE NORTHERN ROCKIES EARLY FRIDAY. THIS WILL INDUCE A RATHER  
IMPRESSIVE SURFACE CYCLONE IN SOUTHERN CANADA. LUCKILY FOR PEOPLE  
TRAVELING, THE STRONGEST FORCING AND DEEP MOISTURE ASSOCIATED WITH  
THIS SYSTEM WILL FOCUS WELL TO OUR NORTH. THERE IS SOME SUGGESTION  
THE HIGHWAY 14 CORRIDOR COULD BE AFFECTED BY PRECIPITATION  
ASSOCIATED WITH THE 700MB FRONT FRIDAY AFTERNOON. LOW LEVEL  
TEMPERATURES WILL BE PLENTY WARM ENOUGH TO ENSURE ANY PRECIPITATION  
WILL FALL AS RAIN. WILL ONCE AGAIN NEED TO BOOST WINDS FRIDAY NIGHT  
IN THE WAKE OF THE FRONTAL PASSAGE.  
 
GENERAL GUIDANCE AGREEMENT AFTER FRIDAY IS FOR DRY CONDITIONS AS  
LONGWAVE RIDGING ALOFT DOMINATES THE NORTHERN PLAINS.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)  
ISSUED AT 524 PM CST MON NOV 20 2017  
 
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION OVERNIGHT, LIKELY  
STARTING IN THE PRE-DAWN HOURS BRINGING GUSTY NORTHWESTERLY WINDS.  
SUSTAINED WINDS AROUND 20 KT WITH GUSTS 30 TO 35 KTS WILL BE  
COMMON. SKIES LOOK TO REMAIN CLEAR FOR MOST AREAS WITH THIS DRY  
COLD FRONT, BUT SITES IN SOUTHWEST MN COULD SEE SHORT-LIVED MVFR  
CLOUD DECK AROUND 2500 FT AGL ON THE LEADING EDGE OF THE FRONT.  
WINDS CONTINUE THROUGH THE DAY TUESDAY, BUT QUICKLY DIMINISH AFTER  
SUNSET.  
 

 
   
FSD WATCHES/WARNINGS/ADVISORIES
 
 
SD...NONE.  
MN...WIND ADVISORY FROM 6 AM TO 2 PM CST TUESDAY FOR MNZ072-081-090.  
 
IA...WIND ADVISORY FROM 6 AM TO 2 PM CST TUESDAY FOR IAZ003.  
 
NE...NONE.  

 
 

 
 
SHORT TERM...FERGUSON  
LONG TERM...FERGUSON  
AVIATION...VANDENBOOGART  
 
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