330  
FXUS63 KFSD 072320  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
520 PM CST FRI FEB 7 2025  
   
KEY MESSAGES  
 
- SNOWFALL FORECAST AMOUNTS/TIMING LARGELY REMAIN ON TRACK FOR  
TONIGHT-SATURDAY. HIGHEST AMOUNTS OF 2 TO 4 INCHES REMAIN OVER  
SOUTHWEST MN WHERE THE WINTER WEATHER ADVISORY IS IN PLACE.  
SNOW TOTALS AROUND AN INCH AS FAR WEST/SOUTH AS HURON, SIOUX  
FALLS, AND SPENCER.  
 
- TEMPERATURES COOL SIGNIFICANTLY FOR MOST OF THE UPCOMING  
WEEK, HOWEVER THE INCOMING AIRMASS REMAINS FAIRLY TYPICAL FOR  
THE SECOND WEEK OF FEBRUARY. A FEW DAYS WITH BELOW ZERO LOW  
TEMPERATURES POSSIBLE THIS WEEK.  
 
- BEYOND SATURDAY, NO SIGNIFICANT SNOW RISKS AHEAD, THOUGH AN  
AREA OF LIGHT SNOW COULD ACCOMPANY/FOLLOW THE ARCTIC FRONT  
PASSAGE ON MONDAY-MONDAY NIGHT. A LOWER CONFIDENCE SYSTEM  
MOVES IN AGAIN BY THE END OF NEXT WEEK.  
 
 
   
DISCUSSION  
 
ISSUED AT 257 PM CST FRI FEB 7 2025  
 
LATE THIS AFTERNOON-SATURDAY: WHILE TODAY HAS BEEN ON THE QUIET SIDE  
ACROSS OUR LOCAL AREA, THE INITIAL SNOW FROM THIS SYSTEM HAS BEEN  
FALLING OVER FAR SOUTHERN NORTH DAKOTA MUCH OF TODAY, AND HAS BEGUN  
EXPANDING INTO FAR NORTHERN SOUTH DAKOTA SINCE LATE MORNING. THIS  
BAND APPEARS TO BE FOCUSED CLOSE TO A ZONE OF STRONG FRONTOGENESIS  
AROUND 600MB WHICH WILL EXTEND EAST INTO PORTIONS OF CENTRAL MN AS  
WE HEAD TOWARD EVENING.  
 
CLOSER TO HOME, A RELATIVELY DRY/MILD SOUTHEAST FLOW HAS PREVAILED  
FOR MUCH OF THE DAY, REINFORCING A DRY LAYER BELOW AN EXPANSIVE MID  
LEVEL CLOUD DECK. THIS DRY LOW LEVEL AIR WILL INITIALLY SLOW THE  
DEVELOPMENT OF SNOW INTO OUR FORECAST AREA THROUGH THE EARLY  
EVENING, BUT PERSISTENT WARM ADVECTION AND INCREASING MID LEVEL  
FRONTOGENESIS AHEAD OF THE APPROACHING SURFACE/UPPER LEVEL WAVE  
SHOULD PRODUCE ENOUGH LIFT TO ALLOW FOR FAIRLY RAPID EXPANSION OF  
THE SNOW THROUGH THE LATTER HALF OF THE EVENING ACROSS PORTIONS OF  
SOUTHEAST/EAST CENTRAL SOUTH DAKOTA AND INTO SOUTHWEST MINNESOTA.  
 
THE WAVE AND ASSOCIATED STRONGER LIFT STILL LOOK TO MOVE EAST OF THE  
AREA PRETTY QUICKLY, WITH THE HEAVIEST SNOWFALL EXPECTED NORTHEAST  
OF A BROOKINGS-WORTHINGTON LINE BETWEEN MIDNIGHT AND 9AM SATURDAY. A  
NEARLY ISOTHERMAL SATURATED PROFILE NEAR TO SLIGHTLY WARMER THAN THE  
DENDRITIC GROWTH ZONE (DGZ), ALONG WITH RELATIVELY LIGHT WINDS  
DURING THIS WINDOW, WILL PROVIDE GOOD CONDITIONS FOR SNOWFLAKE  
GROWTH, WHICH COULD LEAD TO HIGHER SNOWFALL ACCUMULATION RATES AT  
TIMES. IN FACT, THE HREF DOES SHOW MEAN SNOWFALL RATES OF 1/4 TO  
1/2" PER HOUR SLIDING THROUGH PORTIONS OF SOUTHWEST MINNESOTA, WITH  
A LOW (<20%) PROBABILITY FOR SNOWFALL RATES EXCEEDING 1"/HOUR. SO  
WHILE THE HEAVIEST SNOW MAY NOT LAST MORE THAN 4-6 HOURS IN ANY ONE  
LOCATION, WE ARE STILL LOOKING AT A MOST LIKELY RANGE OF SNOWFALL  
BETWEEN 2 AND 4 INCHES, WITH LOCATIONS FROM MARSHALL TO WINDOM  
SEEING A LOW (<20%) CHANCE OF EXCEEDING 4 INCHES.  
 
AS NOTED BY THE PREVIOUS SHIFT, THE POST-FRONTAL COLD ADVECTION ON  
SATURDAY WILL AID IN MIXING SOME STRONGER WIND GUSTS TO THE SURFACE,  
MOSTLY IN THE WAKE OF THE FALLING SNOW. ARW/HRRR TEND TO PERFORM  
WELL IN THESE COLD ADVECTION REGIMES, AND BOTH MODELS INDICATE WINDS  
ATOP OUR MIXED LAYER TOPPING 25KT ACROSS SOUTHWEST MN, WITH STRONGER  
WINDS TOPPING 35KT ACROSS SOUTHWEST PORTIONS OF OUR FORECAST AREA.  
THUS WILL CONTINUE TO FAVOR THE HIGHER END OF WIND GUIDANCE FOR  
SATURDAY, WHICH COULD LEAD TO AREAS OF BLOWING/DRIFTING SNOW INTO  
THE AFTERNOON HOURS. IN ADDITION, A TRAILING WEAK WAVE COMBINED WITH  
THE THERMAL PROFILE COOLING FURTHER INTO THE DGZ MAY ALLOW LIGHT  
SNOW TO LINGER NEAR/EAST OF I-29 THROUGH MIDDAY. AS A RESULT OF THE  
STRONGER WINDS AND LATER END TO LIGHT SNOWFALL, HAVE EXTENDED OUR  
ADVISORY THROUGH 3 PM SATURDAY.  
 
SUNDAY ONWARD: WITH FOCUS ON THE NEAR-TERM SNOWFALL, DID NOT MUCH  
TIME TO EXAMINE THE MID-LONG RANGE FOR FINE DETAILS. IN THE BROAD  
VIEW, HIGHLIGHTS INCLUDE A SECONDARY PUSH OF COLD AIR DROPPING INTO  
THE NORTHERN PLAINS FOR THE START OF THE WORK WEEK. WITH LOW LEVEL  
TEMPERATURES FALLING BACK INTO THE DGZ, ANY LOW LEVEL CLOUDS WILL  
SUPPORT PRODUCTION OF FLURRIES/LIGHT SNOW, AND MODELS ARE LATCHING  
ONTO SOME LIGHT QPF/SNOWFALL DURING THIS TIME MONDAY AFTERNOON AND  
NIGHT. THE COLDEST AIR OF THE WEEK WILL FOLLOW THIS INTO TUESDAY AND  
TUESDAY NIGHT, AND WHILE NOT ANOMALOUSLY COLD ALOFT FOR THIS TIME OF  
YEAR, OUR FRESH SNOW COVER IN PARTS OF THE AREA WILL HELP SURFACE  
TEMPERATURES COLDER WITH HIGHS TUESDAY IN THE SINGLE DIGITS ABOVE  
ZERO, AND LOWS MONDAY NIGHT-TUESDAY NIGHT IN SINGLE DIGITS AND TEENS  
BELOW ZERO. MAY SEE ADDITIONAL COLD WEATHER HEADLINES IN SOME OF THE  
COLDER AREAS ON THESE NIGHTS.  
 
MIDWEEK LOOKS TO BE RELATIVELY QUIET, BUT SOME MODEL SOLUTIONS ARE  
HINTING AT A STRONGER WAVE KICKING OUT OF THE ROCKIES INTO THE  
PLAINS BY LATE NEXT WEEK. MODEL AGREEMENT IS LOW, AND THUS SO IS  
CONFIDENCE IN ANY SPECIFIC DETAILS FOR THIS PERIOD, ASIDE FROM THE  
FACT THAT TEMPERATURES LOOK TO REMAIN COLD ENOUGH THAT SNOW WOULD BE  
THE PRIMARY PRECIPITATION TYPE.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/  
 
ISSUED AT 515 PM CST FRI FEB 7 2025  
 
LIGHT SNOW WILL OVERSPREAD THE AREA FROM NORTHWEST TO SOUTHEAST  
TONIGHT AND CONTINUE INTO SATURDAY MORNING WEST OF THE JAMES  
RIVER VALLEY, AND INTO THE AFTERNOON EAST OF THERE. WITH THAT,  
CEILINGS AND VISIBILITIES WILL FALL INTO THE MVFR/IFR RANGE.  
 
SOUTHEASTERLY WINDS THIS EVENING WILL TRANSITION TO NORTHERLY  
OVERNIGHT, GUSTING 20 TO 30 KTS THROUGH THE DAY ON SATURDAY.  
THIS COULD RESULT IN PATCHY BLOWING AND DRIFTING SNOW, MAINLY  
THROUGH EAST CENTRAL SD AND SOUTHWESTERN MN WHERE SNOWFALL  
AMOUNTS WILL BE HIGHEST.  
 
 
   
FSD WATCHES/WARNINGS/ADVISORIES  
 
SD...NONE.  
MN...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST  
SATURDAY FOR MNZ071-072-080-081.  
IA...NONE.  
NE...NONE.  
 
 
 
 
 
DISCUSSION...JH  
AVIATION...JM  
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