834  
FXUS63 KFSD 230911  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
411 AM CDT TUE MAY 23 2017  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 411 AM CDT TUE MAY 23 2017  
 
LARGE UPPER LOW WILL MOVE SOUTHWARD TODAY ALONG THE EASTERN EDGE OF  
THE FORECAST AREA, WITH AN ATTENDANT SHORT WAVE IN AN EAST TO WEST  
ORIENTATION MOVING THROUGH THIS MORNING. AT THE SURFACE, THE WINDS  
WILL BE RATHER STIRRED UP WITH A WELL MIXED LOWEST KILOMETER, WITH  
MIXED LAYER WINDS SUGGESTING 15 TO 30 MPH FOR THE BALANCE OF THE  
DAY. SCATTERED SHOWERS WILL BE MOVING SOUTHWARD ALONG THE WAVE,  
DRIVEN MAINLY BY PVA AND A SLIGHTLY UNSTABLE 0-6KM LAPSE RATE NEAR  
6C/KM DUE TO COLD AIR ALOFT. HOWEVER, TOOK THE MENTION OF THUNDER  
OUT OF THE FORECAST IN THAT IT LOOKS NOT OVERLY UNSTABLE ENOUGH  
ANYMORE TO MENTION IT. 0-1KM ML CAPE IS VERY MINIMAL, AND MU CAPE IS  
ALL BOTTLED UP IN THE LOWEST KILOMETER WITH VIRTUALLY NONE ABOUT  
900MB. HIGHS TODAY WILL BE MUCH BELOW SEASONAL NORMALS, WITH  
READINGS IN THE 50S.  
 
THE SHOWER ACTIVITY WILL WANE RAPIDLY THIS EVENING AS THE DAYTIME  
HEATING SUBSIDES. CLOUDS SHOULD SLOWLY ERODE HOWEVER THEY COULD BE  
STUBBORN TO TOTALLY LEAVE ALONG AND EAST OF I 29. WITH A BIT OF  
GRADIENT PRODUCING MODEST WIND SPEEDS, LOWS SHOULD STAY IN THE LOWER  
TO MID 40S.  
 
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 411 AM CDT TUE MAY 23 2017  
 
WEDNESDAY INTO THURSDAY LOOKS TO BE WARMER AND MAINLY DRY AS SURFACE  
HIGH PRESSURE MOVES THROUGH THE REGION AND SOUTHERLY FLOW RETURNS.  
SOUTHERLY WINDS APPEAR TO BE FAIRLY STRONG THURSDAY. THERE APPEARS  
TO BE A STRONG ELEVATED MIXED LAYER IN THE 800-600 MB LAYER  
EFFECTIVELY CAPPING THE ATMOSPHERE. A WEAK BOUNDARY IS EXPECTED TO  
SHIFT THROUGH THE REGION LATE ON THURSDAY AND COULD PRODUCE AN  
OUTSIDE CHANCE OF A STORM OR TWO. LOW LEVEL MOISTURE AND  
INSTABILITY APPEAR TO BE LACKING, ALONG WITH ORGANIZED WIND SHEAR SO  
ANYTHING THAT WOULD DEVELOP WOULD LIKELY NOT BE SEVERE.  
 
ALTHOUGH A BIT BREEZY NORTH OF I-90, FRIDAY LOOKS TO BE FAIRLY  
PLEASANT WITH NEAR SEASONAL HIGHS WITH VARIABLE CLOUDS.  
 
NORTHWEST FLOW DEVELOPS THROUGH THE HOLIDAY WEEKEND AS SLOW MOVING  
TROUGH MOVES INTO THE GREAT LAKES REGION. EACH MODEL HITS THAT  
THERE COULD BE A FEW DISTURBANCES ROAMING THROUGH THE REGION THROUGH  
THE WEEKEND, BUT WOULD BE MORE OF A PASSING SHOWER THAN A SUSTAINED  
RAIN EVENT. SEASONAL TEMPERATURES CONTINUE THROUGH THE WEEKEND.  
 
MODELS REALLY DIFFER BY EARLY NEXT WEEK AS THE EC SUGGESTS COOLER  
AIR SPILLING INTO THE UPPER MIDWEST, WHILE THE GFS IS NEARLY 10 C  
WARMER AT 850 MB. GFS ENSEMBLE IS MAINLY CLUSTERING AROUND THE  
OPERATIONAL RUN, SO HARD TO TELL AT THIS POINT WHICH SOLUTION IS  
CORRECT. HAVE LEFT THE BLEND FOR NOW, WHICH IS HEDGING TOWARDS THE  
WARMER GFS SOLUTION.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)  
ISSUED AT 1120 PM CDT MON MAY 22 2017  
 
SHOWERS WILL WORK OUT OF SOUTHWEST MINNESOTA THIS EVENING,  
HOWEVER, ADDITIONAL SHOWERS ALONG WITH MVFR CEILINGS WILL WORK  
BACK INTO THE REGION TOWARDS DAYBREAK ON TUESDAY. SHOWER ACTIVITY  
WILL BE LIGHT LEADING TO PREVAILING VFR CONDITIONS. WINDS WILL BE  
BRISK OUT OF THE NORTHWEST THROUGHOUT THE DAYLIGHT HOURS ON  
TUESDAY.  
 

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

 
 

 
 
SHORT TERM...MJ  
LONG TERM...BT  
AVIATION...BT  
 
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