594  
FXUS63 KFSD 192242  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
542 PM CDT FRI OCT 19 2018  
   
SHORT TERM
 
(THIS EVENING THROUGH SATURDAY)  
ISSUED AT 339 PM CDT FRI OCT 19 2018  
 
AS THE MIXING POTENTIAL DECREASES, THE NORTHWEST WINDS WILL FALL OFF  
RAPIDLY THIS EVENING. HOWEVER LATE TONIGHT AND SATURDAY MORNING, AN  
UPPER TROUGH WILL MOVE SOUTHWARD FROM SOUTH CENTRAL CANADA THROUGH  
THE WESTERN GREAT LAKES, WHICH WILL USHER THROUGH ANOTHER COLD FRONT  
WILL SHARPLY COOLER AIR FOR SATURDAY. TEMPERATURES MAY NOT MOVE A  
WHOLE LOT OFF OF MORNING LOWS EAST OF INTERSTATE 29, WITH ONLY LOWER  
40S FOR HIGHS IN SOUTHWEST MN. TEMPERATURES WILL BE PROGRESSIVELY  
WARMER HEADING TO THE SOUTHWEST, WITH LOWER 50S IN OUR SOUTH CENTRAL  
SD ZONES. WE HAVE SOME 40 KNOT WINDS AT THE TOP OF THE MIXED LAYER  
ALONG AND EAST OF I 29 LATE TONIGHT AND SATURDAY MORNING. WHEN THIS  
LAYER FULLY MIXES OUT TOWARD 14Z OR 15Z, THERE MAY BE A BRIEF WINDOW  
OF WINDS NEAR ADVISORY CRITERIA FROM WORTHINGTON/WINDOM MN,  
SOUTHWARD THROUGH STORM LAKE IA. HOWEVER BY 18Z, BOTH THE WINDS IN  
THE MIXED LAYER AND THE GRADIENT BEGIN TO RELAX. THEREFORE DUE TO  
THE BRIEF TIME FRAME, DECIDED AT THIS TIME NOT TO ISSUE A HEADLINE  
FOR THAT LOCATION.  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH FRIDAY)  
ISSUED AT 339 PM CDT FRI OCT 19 2018  
 
AS THE SURFACE HIGH MOVES EAST, WARM AIR ADVECTION WILL RETURN  
SATURDAY NIGHT. A SOUTH TO SOUTHWESTERLY FLOW WILL BEGIN AND  
SATURDAY NIGHT IS A CLASSIC FOR WIND ACROSS THE BUFFALO RIDGE AREA  
OF SOUTHWEST MN. THERE IS 40 KNOTS AT 925MB IN SOUTHWEST MN, SO IT  
WILL NOT TAKE A WHOLE LOT TO MAKE THINGS QUITE WINDY ALONG THE RIDGE  
LATER SATURDAY NIGHT AND EARLY SUNDAY. THEREFORE MANUALLY RAISED  
WIND SPEEDS INTO THE WINDY CATEGORY FOR THE BUFFALO RIDGE IN THAT  
TIME FRAME. SUNDAY WILL BE A WARM DAY WITH PRE-FRONTAL WARMING. A  
BREEZY SOUTHWEST FLOW WILL EXIST THROUGH THE ENTIRE DAY IN OUR  
SOUTHEAST ZONES ALLOWING FOR A DRAMATIC WARMUP, BUT RAISED  
TEMPERATURES ABOVE SUPERBLEND HIGHS ACROSS THE ENTIRE FORECAST AREA.  
MANY OF THESE WARMER HIGHS ARE ONLY MIXED TO ABOUT 925-900MB SO IF  
MIXING IS DEEPER, WHICH COULD CERTAINLY HAPPEN ESPECIALLY IN  
NORTHWEST IA, THESE ALTERED HIGHS COULD BE EVEN WARMER.  
 
A COLD FRONT WILL MOVE THROUGH SUNDAY NIGHT, HOWEVER THE COLD AIR  
ADVECTION PUSH IS RATHER WEAK. THEREFORE HIGHS MONDAY THROUGH  
WEDNESDAY WILL MAINLY BE IN THE 50S UNDER THE INFLUENCE OF A LARGE  
AREA OF HIGH PRESSURE. THERE IS MODEL AGREEMENT IN SHOWING A BROAD  
UPPER TROUGH MOVING ACROSS THE PLAINS LATER WEDNESDAY THROUGH  
THURSDAY NIGHT. MOISTURE WILL BECOME FAIRLY DEEP WITH EVEN STRATUS  
MOVING IN BY WEDNESDAY NIGHT, SO THE CHANCES FOR LIGHT SHOWERS ARE  
STILL WARRANTED LATER NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)  
ISSUED AT 538 PM CDT FRI OCT 19 2018  
 
VFR CONDITIONS THROUGH THE TAF PERIOD. LOW LEVEL WIND SHEAR WILL  
DEVELOP AT ALL TAF SITES OVERNIGHT. NORTHWESTERLY WINDS WILL PICK  
UP ON SATURDAY MORNING, GUSTING 20 TO 30 KTS INTO THE AFTERNOON.  
 

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

 
 

 
 
SHORT TERM...MJ  
LONG TERM...MJ  
AVIATION...JM  
 
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