237
FXUS63 KFSD 292338
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
538 PM CST WED JAN 29 2025
KEY MESSAGES
- MILD TEMPERATURES IN THE 40S AND 50S WILL CONTINUE INTO THIS
WEEKEND, WITH THURSDAY EXPECTED TO BE THE WARMEST DAY OF THE
PERIOD.
- LOW (10-30%) CHANCE THAT A STORM SYSTEM MOVING THROUGH THE
CENTRAL PLAINS WILL SPREAD LIGHT RAIN INTO AREAS SOUTH OF A
YANKTON SD TO SPENCER IA LINE, MAINLY TOWARD US HIGHWAY 20,
THURSDAY AFTERNOON AND EVENING. HIGH (90+%) PROBABILITY THAT
RAINFALL, IF IT OCCURS, REMAINS LESS THAN 0.10 INCH.
- COOLER AND MORE UNSETTLED PATTERN RETURNS SUNDAY NIGHT
THROUGH THE END OF THE WEEK, THOUGH NO SIGNIFICANT STORM
SYSTEMS ARE EXPECTED.
DISCUSSION
ISSUED AT 226 PM CST WED JAN 29 2025
TONIGHT-THURSDAY NIGHT: SURFACE HIGH PRESSURE WHICH HAS PROVIDED
MUCH LIGHTER WINDS ACROSS THE AREA TODAY HAS SHIFTED INTO MINNESOTA
AND IOWA, FOLLOWED BY A MORE SOUTHERLY FLOW WHICH WILL PREVAIL INTO
TONIGHT. A MODEST SOUTHWESTERLY LOW LEVEL JET OF 35-40KT WILL RESULT
IN BREEZIER CONDITIONS ACROSS OUR HIGHER ELEVATIONS IN SOUTHWEST MN,
AS WELL AS GREGORY COUNTY IN SOUTH CENTRAL SD OVERNIGHT, BUT THE LLJ
AND THUS SURFACE WINDS WILL DECREASE AGAIN PRIOR TO SUNSET.
ATTENTION THEN TURNS TO A STORM SYSTEM DEVELOPING OVER THE CENTRAL
TO SOUTHERN ROCKIES TONIGHT. THIS SYSTEM WILL SLIDE EAST INTO THE
CENTRAL PLAINS THURSDAY INTO THURSDAY NIGHT, WITH A BAND OF HEAVIER
PRECIPITATION EXPECTED TO DEVELOP ON THE NORTH SIDE FROM EASTERN
NEBRASKA INTO IOWA THURSDAY NIGHT. MODELS LARGELY SEEM TO FAVOR
KEEPING THIS PRECIPITATION SHIELD SOUTH OF OUR FORECAST AREA, OR
PERHAPS JUST BRUSHING THE HIGHWAY 20 CORRIDOR NEAR/EAST OF SIOUX
CITY, WITH ENSEMBLES SHOWING A LOW (30%) PROBABILITY OF MEASURABLE
RAINFALL AT SOME POINT THURSDAY AFTERNOON OR EVENING NEAR/SOUTH OF A
SIOUX CITY-STORM LAKE LINE. HOWEVER, IF RAIN DOES DEVELOP THIS FAR
NORTH, LIGHT RAIN IS CERTAINLY FAVORED WITH ENSEMBLES SHOWING A HIGH
(90+%) PROBABILITY THAT TOTAL RAINFALL REMAINS LESS THAN 0.10 INCH.
GREATER CONFIDENCE THAT THE SYSTEM WILL SPREAD SOME THICKER CLOUD
COVER INTO OUR SOUTHERN COUNTIES WHICH COULD KEEP TEMPERATURES FROM
REACHING THEIR FULL POTENTIAL THURSDAY AFTERNOON, THOUGH ANTICIPATE
THAT MOST AREAS WILL PEAK IN THE UPPER 40S TO MID 50S. TEMPERATURES
REMAIN WARM ENOUGH WHILE WE HAVE PRECIPITATION CHANCES THROUGH THE
EVENING THAT RAIN IS THE EXPECTED TYPE. HOWEVER, IF ANY AREAS SEE
MORE THAN A TRACE-0.01" AMOUNTS, THERE IS A CHANCE FOR REFREEZE BY
FRIDAY MORNING AS TEMPERATURES FALL BACK BELOW FREEZING BY DAYBREAK.
FRIDAY-SUNDAY: FRIDAY WILL BE A SOMEWHAT COOLER, THOUGH STILL MILD
DAY IN THE WAKE OF THE DEPARTING SYSTEM TO OUR SOUTH, AS NORTHERLY
FLOW PULLS SUB-ZERO 925-850MB AIR BACK INTO AT LEAST NORTHERN PARTS
OF THE FORECAST AREA. THE RELATIVE COOL-DOWN WILL BE BRIEF, THOUGH,
AS WARM ADVECTION INCREASES AGAIN LATER FRIDAY NIGHT/SATURDAY AHEAD
OF A MODEST MID-LEVEL WAVE SLIDING THROUGH THE NORTHERN PLAINS.
MOISTURE IS PRETTY LIMITED ACROSS OUR FORECAST AREA, SO AT THIS
POINT WILL BE CARRYING A DRY FORECAST. HOWEVER, DETERMINISTIC RUNS
OF GFS/NAM DO HINT AT SOME VERY LIGHT PRECIPITATION DEVELOPING IN
THE WARM ADVECTION OVER SOUTHWEST MINNESOTA LATE FRIDAY NIGHT OR
SATURDAY MORNING. ENSEMBLES ARE NOT OVERLY EXCITED, BUT DO SUPPORT
A LOW (10-20%) CHANCE OF MEASURABLE PRECIPITATION. IF THIS WERE
TO OCCUR, THERMAL PROFILES WOULD FAVOR LIGHT SNOW, AND CHANCES ARE
HIGHER FARTHER NORTHEAST INTO MINNESOTA, SO THOSE WITH TRAVEL
PLANS MAY WISH TO MONITOR THE LATEST FORECAST FOR POSSIBLE MINOR
TRAVEL IMPACTS SATURDAY MORNING.
TEMPERATURES DO REBOUND BEHIND THIS WAVE WITH HIGHS SATURDAY FROM
THE LOWER 40S IN SOUTHWEST MINNESOTA TO MID 50S IN THE MISSOURI
RIVER VALLEY. THE MILD AIR STICKS AROUND INTO SUNDAY, BUT A COLD
FRONT IS CURRENTLY SLATED TO PUSH SOUTHEAST ACROSS THE FORECAST AREA
SOMETIME SUNDAY INTO SUNDAY EVENING, AND THIS WILL BRING AN END TO
OUR STRETCH OF MILD CONDITIONS AS WE MOVE INTO THE FIRST WEEK OF
FEBRUARY.
SUNDAY NIGHT-WEDNESDAY: WHILE CONFIDENCE IS RATHER HIGH THAT WE
WILL SEE TEMPERATURES TREND TOWARD MORE SEASONABLE OR EVEN SLIGHTLY
BELOW NORMAL BY NEXT WEEK, CONFIDENCE IS MUCH LOWER REGARDING
PRECIPITATION CHANCES THROUGH THIS PERIOD. A MORE UNSETTLED ZONAL
FLOW PATTERN LOOKS TO SET UP THROUGH AT LEAST THE FIRST HALF OF
NEXT WEEK. WHILE WE ARE NOT SEEING SIGNALS FAVORING DEVELOPMENT
OF ANY SIGNIFICANT STORM SYSTEMS, A SERIES OF SUBTLE WAVES WITHIN
THE ZONAL FLOW COULD BRING PERIODIC CHANCES FOR PRECIPITATION,
WITH LIGHT SNOW BEING THE PREFERRED TYPE GIVEN THE COLDER AIR
MASS WHICH WILL BE IN PLACE. DIFFICULT TO PIN DOWN ANY FAVORED
TIME FRAME FOR THESE LIGHT SNOW CHANCES AT THIS RANGE SO WILL BE
STICKING WITH MULTIPLE PERIODS OF LOW NBM POPS FOR NOW.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 526 PM CST WED JAN 29 2025
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. WINDS REMAIN
RELATIVELY LIGHT, AROUND 10 KNOTS OR LESS. SOUTHERLY SURFACE
WINDS SHIFT THROUGH THE PERIOD, BECOMING NORTHWESTERLY BY
THURSDAY AFTERNOON AND EVENING. SOUTHWESTERLY TO WESTERLY LLJ
TONIGHT WILL LEAD TO PERIODS OF LLWS FOR SOUTH CENTRAL SD AND
AREAS ALONG NORTH OF I-90 INTO SOUTHWESTERN MN, INCLUDING AT
KHON AND KFSD.
LOWER CLOUDS INCREASE THURSDAY MORNING THROUGH THE DAYTIME HOURS
FOR THE US HWY 20 CORRIDOR TOWARD US HWY 18 AS A SYSTEM PASSES
WELL TO OUR SOUTH. MAY SEE SOME LIMITED AREAS OF MVFR (AROUND
3KFT) CEILINGS EAST OF KSUX AT THE VERY END OF THE PERIOD, BUT
CONFIDENCE IS LOW. ISOLATED SHOWERS ARE POSSIBLE FOR THIS AREA
AFTER 30.21Z; HOWEVER, WITH UNCERTAINTY IN COVERAGE AND LOW
CHANCES, HAVE OMITTED FROM KSUX FOR NOW.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...JH
AVIATION...SG
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