626  
FXUS63 KFSD 202320 AAA  
AFDFSD  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
520 PM CST THU FEB 20 2020  
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY)  
ISSUED AT 328 PM CST THU FEB 20 2020  
 
TONIGHT: WINDS WILL REMAIN ON THE BREEZY SIDE INTO THE EVENING  
HOURS, BUT WILL DECREASE AS A STRONG SURFACE INVERSION SETS UP  
DECOUPLING US FROM THE WINDS ALOFT. TEMPERATURES WILL REMAIN FAIRLY  
CONSTANT THROUGHOUT THE NIGHT, AS RADIATIONAL COOLING BATTLES  
AGAINST THE WARM AIR BEING ADVECTED INTO THE REGION.  
 
FRIDAY: AS THE SURFACE HIGH PRESSURE CASUALLY SLIDES SOUTHWARDS, THE  
PRESSURE GRADIENT WILL TIGHTEN AND THE AFOREMENTIONED INVERSION WILL  
GIVE WAY LATER IN THE MORNING ALLOWING WINDS TO INCREASE. DUE TO THE  
SOUTHERLY WINDS, WARM AIR WILL CONTINUE TO ADVECT INTO THE AREA  
LEADING TO ABOVE NORMAL TEMPERATURES. THANKS TO THE STRONG SUNSHINE  
ON THURSDAY AND ABOVE FREEZING TEMPERATURES ON FRIDAY, THE SNOW PACK  
IS NOT IDEAL FOR BLOWING SNOW...BUT PATCHY BLOWING SNOW REMAINS A  
POSSIBILITY LARGELY ALONG THE BUFFALO RIDGE IN SW MN.  
   
LONG TERM
 
(FRIDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 328 PM CST THU FEB 20 2020  
 
FRIDAY NIGHT: DUE TO THE MELTING SNOW THAT IS EXPECTED DURING THE  
DAY, PATCHY FOG MAY DEVELOP FRIDAY NIGHT ALONG A LINE FROM YANKTON,  
SD TO SPENCER, IA. WINDS AND SOME MID-LEVEL CLOUDS WILL LARGELY  
LIMIT HOW MUCH FOG DEVELOPS, BUT IF THE WINDS BECOME CALMER THAN  
CURRENTLY EXPECTED THERE WILL LIKELY BE MORE FOG.  
 
SATURDAY: ANOTHER QUIET DAY IS IN STORE FOR SATURDAY, WITH SOME  
CLOUDS HANGING AROUND IN THE MORNING HOURS THANKS TO AN UPPER LEVEL  
DISTURBANCE MOVING THROUGH. AREAS ALONG THE MISSOURI RIVER COULD  
SEE TEMPERATURES REACH 50, WITH AREAS AS FAR NORTH AS HURON AND  
MARSHALL POSSIBLY SEEING 40. SIMILAR TO FRIDAY NIGHT, MELTING SNOW  
COULD LEAD TO ANOTHER PATCHY FOGGY NIGHT AS WINDS ARE QUITE  
LIGHT.  
 
SUNDAY: A CALM DAY WITH ABOVE AVERAGE TEMPERATURES INTO THE EARLY  
AFTERNOON, BUT CLOUD COVERAGE WILL BE INCREASING THROUGHOUT THE DAY.  
MODELS HAVE BEEN PERSISTENT IN PRODUCING A COLORADO LOW WITH THE  
CENTER OF THE CIRCULATION FORECAST TO SKIRT SOUTH AND EAST OF OUR  
AREA, POSSIBLY BRINGING LIGHT WINTRY PRECIPITATION TO THE  
SURROUNDING SIOUX CITY AREA AND OUT TOWARDS STORM LAKE INTO THE  
OVERNIGHT HOURS.  
 
MONDAY-THURSDAY: MODELS CONTINUE TO DISAGREE ON HOW TO HANDLE THE  
LONGER RANGE PATTERN FOR NEXT WEEK. GFS REMAINS THE MODEL THAT  
PRODUCES THE MOST PRECIPITATION, WITH THE GEM AND ECMWF GIVING US  
LESS. DUE TO THE UNCERTAINTY, LEFT POPS AT A CHANCE MONDAY INTO  
WEDNESDAY MORNING. ONE THING THAT THE MODELS DO AGREE ON IS THAT  
TEMPERATURES WILL DROP BACK DOWN BELOW NORMAL TEMPERATURES LATER  
IN THE WEEK.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 516 PM CST THU FEB 20 2020  
 
EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. SOUTH WINDS  
AT OR BELOW 10 KTS ARE EXPECTED OVERNIGHT AT THE SURFACE, BUT LOW  
LEVEL WIND SHEAR DEVELOPS LATE TONIGHT WITH A SOUTHWESTERLY LOW  
LEVEL JET. EXPECT WINDS TO BECOME MORE SOUTHWESTERLY AND  
EVENTUALLY WESTERLY ON FRIDAY WITH GUSTY WINDS UP TO 30 KTS  
DEVELOPING FOR LATE MORNING THROUGH THE AFTERNOON, STRONGEST IN  
NORTHWEST IA AND SOUTHWEST MN.  
 

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

 
 

 
 
SHORT TERM...TRELLINGER  
LONG TERM...TRELLINGER  
AVIATION...BP  
 
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