028
FXUS63 KFSD 150441
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1041 PM CST FRI FEB 14 2025
KEY MESSAGES
- PERIODS OF LIGHT SNOW AND PATCHY BLOWING SNOW THIS AFTERNOON THROUGH
SATURDAY NIGHT. MOST AREAS WILL SEE AROUND AN INCH OR LESS.
- A SMALL, ENHANCED BAND OF 3-5 INCHES OF SNOW MAY IMPACT
PORTIONS OF NORTHWEST IOWA TONIGHT-EARLY SATURDAY. WHILE THE
PROBABILITY OF THIS SNOWBAND IS INCREASING (80%), CONFIDENCE
IN THE EXACT LOCATION IS STILL LOWER (40%). MOST INDIVIDUAL
MODEL OUTPUT IS INDICATING THAT THIS BAND OF HIGHER AMOUNTS IS
ABOUT 20-30 MILES WIDE. A SMALL WINTER WEATHER ADVISORY IS IN
EFFECT OVERNIGHT TONIGHT INTO SATURDAY AFTERNOON MAINLY NEAR
AND SOUTH OF A SIOUX CITY TO OKOBOJI LINE.
- TEMPERATURES AS MUCH AS 20 TO 30 DEGREES BELOW NORMAL RETURN SATURDAY
THROUGH MUCH OF THE NEXT WEEK, WITH NEAR RECORD COLD POSSIBLE
MONDAY-WEDNESDAY. THE RETURN TO SCHOOL ON TUESDAY MORNING
WILL BE DANGEROUSLY COLD, IN FACT THE MORNING COMMUTES FROM
MONDAY MORNING THROUGH THURSDAY MORNING WILL LIKELY SEE WIND
CHILL VALUES OF 20 BELOW TO 40 BELOW ZERO.
DISCUSSION
ISSUED AT 220 PM CST FRI FEB 14 2025
UPPER LEVEL LOW PRESSURE MOVING INTO COLORADO THIS AFTERNOON WILL
MOVE INTO KANSAS, NEBRASKA AND IOWA LATER TONIGHT INTO SATURDAY. THE
MAIN FOCUS FOR THE IMMEDIATE VICINITY WILL THE LEAD PIECE OF ENERGY
THAT WORKS INTO THE AREA LATER TONIGHT, AND WILL LIKELY AID IN
ENHANCING THE MID LEVEL FRONTAL FORCING. THE INITIAL CHALLENGE
GETTING SNOW GOING WILL BE SOME DRIER AIR BELOW ABOUT 700 MB. ALL
MODELS ARE CONSISTENT ON SATURATING THIS LEVEL AND LAYERS BELOW SO
FOR NOW THE EXPECTATION IS THAT THE DRY LAYER WILL NOT FULLY IMPEDE
SNOWFALL DEVELOPMENT. A QUICK LOOK AT MODEL SOUNDINGS SUGGESTS THAT
LAPSE RATES INCREASE NICELY ABOVE ABOUT 750 MB WHICH MAY INDICATE
THE LEVEL THAT IS POISED TO PRODUCE THE BEST BANDING. WHEN LOOKING
AT THE 700-750 MB FRONTAL FORCING, LATE EVENING INTO SATURDAY
MORNING THE FORCING TIGHTENS NICELY FROM ABOUT SIOUX CITY TO STORM
LAKE, LEAVING SOME QUESTION MARKS ON HOW FAR NORTH THE HIGHER
SNOWFALL RATES MAY FALL.
AS FOR POTENTIAL SNOWFALL AMOUNTS, THE LATEST GFS AND NAM BOTH
INDICATE A HALF AN INCH OF LIQUID, UP TO THREE QUARTERS IN THE GFS,
ROUGHLY ALONG A LINE FROM SIOUX CITY TO SPENCER IA. GIVEN THE
EXPECTATION OF ROUGHLY 10:1 SNOW RATIOS INITIALLY WHICH WILL
INCREASE TO 15-18:1 THIS WOULD EQUATE TO ABOUT 4-8" OF SNOW. ONE
NOTE, THE GFS AMOUNT OF THREE QUARTERS INCH LIQUID WOULD PLACE IT IN
THE 90%+ PERCENTILE OF THE GEFS OUTPUT. AND ALSO OF NOTE THE GEFS
90TH PERCENTILE KEEPS SNOWFALL AMOUNTS 5" OR LESS. THE LATEST SREF
OUTPUT STILL SHOWING ABOUT A 20-40 PERCENT CHANCE FOR 4"+ IN THIS
AREA.
ONCE THIS SYSTEM PASSES ON SATURDAY, COLDER AIR WILL RETURN WITH
HIGHS GENERALLY IN THE TEENS SATURDAY AND WIND CHILLS BELOW ZERO
WITH NORTHERLY WINDS GUSTING TO AROUND 30 MPH.
SATURDAY NIGHT INTO SUNDAY MORNING WILL BE THE BIGGER PUSH OF COLD
AIR AS NORTHWEST FLOW ALOFT ALLOWS MUCH COLDER AIR TO SETTLE
SOUTHWARD. SUNDAY MORNING LOWS SHOULD BE ABOUT 5-10 BELOW ZERO WITH
HIGHS IN THE SINGLE DIGITS ABOVE ZERO. THERE WILL BE A DECENT CHANCE
FOR A COLD WEATHER ADVISORY FOR LATE SATURDAY NIGHT INTO SUNDAY
MORNING.
THE NEXT CHANCE FOR SNOW WILL ARRIVE SUNDAY NIGHT INTO MONDAY AS A
SYSTEM TO SOUTH MOVES BY FAIRLY QUICKLY. AN INCH OR SO OF
ACCUMULATION WILL BE POSSIBLE ALONG THE MISSOURI RIVER VALLEY WITH
THE 90TH PERCENTILE FROM THE GEFS AND EC ENSEMBLE PUSHING THAT
CLOSER TO 2-2.5". WILL BE SOMETHING TO WATCH.
THE MAIN STORY NEXT WEEK WILL BE A POOL OF VERY COLD AIR AND A LARGE
LOW PRESSURE ALOFT IN CENTRAL CANADA ESSENTIALLY REFRESHING THIS
COLD FLOW OF AIR ACROSS THE NORTHERN PLAINS. THE NAEFS PERCENTILES
SHOW THAT TEMPERATURES ALOFT MONDAY INTO THURSDAY WILL BE NEAR
HISTORICAL MINIMUMS FOR THIS TIME OF YEAR. WITH THIS IN MIND, HIGH
TEMPERATURES ACROSS THE AREA WILL SEE A GOOD CHANCE FOR SOME RECORD
COLD HIGH TEMPERATURES.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1040 PM CST FRI FEB 14 2025
MVFR STRATUS BLANKETS THE AREA LATE THIS EVENING. A FEW LOCATIONS
HAVE GONE UP TO VFR LEVELS AND OTHERS DOWN TO IFR LEVELS HOWEVER.
THAT SAID. DO EXPECTED MVFR CEILINGS TO PERSIST THROUGH THE MAJORITY
OF THE TAF PERIOD. A BAND OF SNOW REMAINS ON TRACK TO DEVELOP DURING
THE OVERNIGHT HOURS. THIS BAND WILL PUSH INTO LOCATIONS ALONG AND
SOUTH OF A KSUX TO KSPW LINE. LOCATIONS UNDER THE BAND WILL SEE
CEILINGS AND VISIBILITIES FALL TO MVFR/IFR/LIFR LEVELS.
THE BAND WON'T LAST LONG THOUGH AS IT WILL QUICKLY PUSH EAST OF THE
AREA BY THE MID MORNING HOURS. THIS WILL LEAVE THE PREVIOUSLY
MENTIONED MVFR CEILINGS AND BREEZY NORTHERLY WINDS WITH GUSTS UP TO
25 KNOTS EXPECTED FOR THE AFTERNOON HOURS. A SECOND CHANCE FOR LIGHT
SNOW IS POSSIBLE WEST OF THE JAMES RIVER TOMORROW AFTERNOON.
HOWEVER, LATEST GUIDANCE HAS BACKED OFF ON THIS POTENTIAL DUE TO
LESS SATURATION BEING AVAILABLE. AS SUCH, HAVE NOT INCLUDED ANY
PROB30 GROUPS IN KHONS TAF. THE NORTHERLY WINDS WILL FINISH OUT THE
TAF PERIOD ALONG WITH CEILINGS BEGINNING TO RISE BACK TO VFR
STATUS.
FSD WATCHES/WARNINGS/ADVISORIES
SD...WINTER WEATHER ADVISORY UNTIL 3 PM CST SATURDAY FOR SDZ071.
MN...NONE.
IA...WINTER WEATHER ADVISORY UNTIL 3 PM CST SATURDAY FOR IAZ003-013-
014-020>022-031-032.
NE...WINTER WEATHER ADVISORY UNTIL 3 PM CST SATURDAY FOR NEZ013-014.
DISCUSSION...08
AVIATION...MEYERS
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