991
FXUS63 KFSD 230440
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1040 PM CST SUN DEC 22 2024
KEY MESSAGES
- PRECIPITATION REMAINS POSSIBLE (~10% CHANCE) ACROSS PARTS OF SOUTHWEST
MINNESOTA TONIGHT. LITTLE TO NO ACCUMULATION IS EXPECTED,
WHICH SHOULD ALLOW FOR A SMOOTH MONDAY MORNING COMMUTE WITHOUT
ANY ISSUES.
- ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR MONDAY THROUGH NEXT WEEKEND.
PRECIPITATION CHANCES LOOK TO RETURN DIRECTLY AFTER CHRISTMAS
ON THURSDAY AND FRIDAY. HIGH CONFIDENCE (80-90% CHANCE) FOR
TEMPERATURES TO BE ABOVE FREEZING, KEEPING THE PRECIPITATION
TYPE AS RAIN.
- TRAVEL IMPACTS THIS WEEK LOOK TO BE MINIMAL ACROSS THE
NORTHERN PLAINS.
DISCUSSION
ISSUED AT 236 PM CST SUN DEC 22 2024
QUIET CONDITIONS PERSIST THIS AFTERNOON BETWEEN A MIX OF SUN AND MID
TO HIGH LEVEL CLOUDS. HIGH TEMPERATURES HAVE WARMED TO THE 30S AND
40S, WARMEST ALONG THE MISSOURI VALLEY. THE CLOUDS ARE DRIVEN BY A
SHORTWAVE TROUGH PUSHING THROUGH THE AREA. WHILE THE BEST FORCING
FOR ASCENT IS QUICKLY MOVING EAST THIS AFTERNOON, THE MAIN VORTICITY
LOBE WILL PASS THROUGH THE FORECAST AREA TONIGHT. HOWEVER, THIS
FORCING FOR ASCENT IS TOO FAR ALOFT AND WILL NOT BE ABLE TO REACH
DOWN CLOSER TO THE SURFACE. THE BETTER MID LEVEL MOISTURE WILL HAVE
DEPARTED EAST BY TONIGHT BUT THE LOW LEVELS WILL SATURATE AS BETTER
MOISTURE IS ADVECTED IN FROM NORTH DAKOTA. WITH MINIMAL FORCING AT
BEST CLOSER TO THE SURFACE, AM NOT EXPECTING MEANINGFUL
PRECIPITATION TO DEVELOP LET ALONE REACH THE SURFACE. THE EXCEPTION
IS THAT PARTS OF SOUTHWEST MINNESOTA COULD SEE FLURRIES AS THE MOIST
LOW LEVELS WILL LIE IN THE SECONDARY DENDRITIC GROWTH ZONE (DGZ).
HOWEVER, THE MAIN DGZ IS UNSATURATED AND COULD RESULT IN VERY LIGHT
MIXED PRECIPITATION MIXING IN WITH THE FLURRIES. THIS SHOULD NOT
RESULT IN ANY MEANINGFUL TRAVEL IMPACTS BUT CAN'T RULE OUT A FEW
SLICK SPOTS ON UNTREATED SURFACES IF PRECIPITATION IS ABLE TO REACH
THE SURFACE. ANY CHANCE FOR PRECIPITATION WILL COME TO AN END BY
SUNRISE TOMORROW MORNING. LOW TEMPERATURES ARE EXPECTED TO FALL TO
THE 20S.
THE FIRST HALF OF THE WEEK LOOKS TO REMAIN DRY WITH A CONTINUATION
OF TEMPERATURES WARMING TO NEAR TO ABOVE AVERAGE AS UPPER LEVEL
RIDGING BUILDS INTO THE CENTRAL US. THE RIDGING WILL 850 MB
TEMPERATURES UP TO ABOUT 1 STANDARD DEVIATION ABOVE AVERAGE PER THE
NAEFS ENSEMBLE. THIS WILL RESULT IN HIGH TEMPERATURES UP TO THE 20S
TO 40S, COLDEST ON MONDAY AND WARMEST ON WEDNESDAY. LIGHT WINDS ARE
EXPECTED ON MONDAY AND TUESDAY, KEEPING AND ISSUES AT BAY FOR
HOLIDAY TRAVEL. WEDNESDAY, CHRISTMAS DAY, WILL BE THE WARMEST DAY
WITH HIGH TEMPERATURES IN THE MID 30S TO MID 40S. MARGINALLY BREEZY
SOUTHEASTERLY WINDS AND PARTLY CLOUDY SKIES WILL MAKE FOR A BIT
COOLER CONDITIONS THOUGH AS WIND CHILLS WILL MAKE IT FEEL NEAR TO
BELOW FREEZING. LOW TEMPERATURES WILL FALL TO THE 20S WEDNESDAY
NIGHT.
ANOTHER UPPER LEVEL WAVE WILL EJECT FROM THE ROCKY MOUNTAINS ON
THURSDAY. THE BEST DYNAMICS WITH THIS WAVE LOOK TO REMAIN WELL SOUTH
OF THE FORECAST AREA, ACROSS THE CENTRAL AND SOUTHERN PLAINS.
HOWEVER, THERE IS UNCERTAINTY REGARDING HOW THIS WAVE WILL EVOLVE.
THE DETERMINISTIC GFS AND CANADIAN HAVE THE WAVE BECOMING NEGATIVELY
TITLED AND PUSHING INTO THE UPPER MIDWEST. THE DETERMINISTIC EURO ON
THE OTHER HAND, HAS THE WAVE PUSHING FURTHER EASTWARDS AND WEAKENING
MUCH MORE QUICKLY. CLUSTER ANALYSIS SHOWS A SIMILAR PICTURE TO WHAT
THE DETERMINISTIC MODELS HAVE BEEN SHOWING BUT IS CLOSER TO THE EURO
IN A MORE EASTWARD PATH. EVEN WITH THE WAVE MOVING MORE EASTWARDS,
PRECIPITATION MAY MAKE ITS WAY BACK TO THE REGION. THE MOST FAVORED
CLUSTER SHOWS INCREASING PROBABILITIES, UP TO A 30-50% CHANCE FOR
EXCEEDING A TENTH OF AN INCH OF LIQUID QPF. THIS SAME PROBABILISTIC
RANGE CONTINUES THROUGH FRIDAY BEFORE THE WAVE COMPLETELY PULLS AWAY
FROM OUR AREA. GIVEN HOW THESE PROBABILITIES CAN CHANGE OVER THE
COMING DAYS HAVE LEFT MODEL BLENDED POPS AT THIS TIME. IN TERMS OF
PRECIPITATION TYPE, THIS IS LOOKING TO BE A PURELY RAIN EVENT WITH
LITTLE TO NO WINTRY PRECIPITATION INVOLVED. ALL OF THE CLUSTERS
SUPPORT THIS AS THEY ALL SHOW 80-90%+ CHANCE FOR LOW LEVEL
TEMPERATURES TO REMAIN ABOVE FREEZING. AS OF NOW, HIGH TEMPERATURES
IN THE 30S TO LOW 40S IS LIKELY FOR THURSDAY AND FRIDAY.
PRECIPITATION CHANCES COULD CONTINUE THROUGH THE WEEKEND BUT THIS IS
MORE UNCERTAIN GIVEN HOW MEDIUM RANGE GUIDANCE VARIES MUCH MORE IN
HOW THE UPPER LEVEL PATTERN EVOLVES. HAVE AGAIN CONTINUED WITH MODEL
BLENDED POPS. TEMPERATURES LOOK TO REMAIN ABOVE AVERAGE IN THE 30S
AND 40S.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1030 PM CST SUN DEC 22 2024
VFR CONDITIONS WILL TRANSITION TO MOSTLY IFR AND LIFR CONDITIONS
THIS TAF PERIOD MOSTLY DUE TO INCREASING LOW LEVEL STRATUS.
TAKING A LOOK AT SATELLITE IMAGERY, OVERCAST SKIES CONTINUE
ACROSS THE REGION WITH LIGHT WINDS THIS EVENING. AS A QUICK
SHORTWAVE APPROACHES FROM THE NORTHWEST LATE TONIGHT, EXPECT
CEILINGS TO GRADUALLY DECREASE INTO IFR TO LIFR THRESHOLDS FOR
MOST OF THE MORNING AS A FEW POCKETS OF FLURRIES DEVELOP WITHIN
THE STRATUS. OTHERWISE, EXPECT CEILING TO GRADUALLY INCREASE BY
THE EARLY AFTERNOON BECOMING MORE MVFR FOR THE REST OF THE TAF
PERIOD. LASTLY, AS LIGHT NORTHWESTERLY WINDS BECOME MORE LIGHT
AND VARIABLE BY MONDAY NIGHT; LINGERING LOW-LEVEL MOISTURE DUE
TO MELTING SNOW WILL LEAD TO AREAS OF FOG DEVELOPING ACROSS
PARTS OF THE AREA TO END THE TAF PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...MEYERS
AVIATION...GUMBS
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