514
FXUS63 KFSD 090823
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
323 AM CDT SUN MAR 9 2025
KEY MESSAGES
- AN EXTENDED PERIOD OF SEASONALLY WARM TEMPERATURES CONTINUES
THIS WEEKEND AND THROUGH MUCH OF THE UPCOMING WEEK. HIGH ARE
LIKELY TO PUSH RECORD VALUES MONDAY AND AGAIN TOWARDS THE END
OF THE WEEK.
- ELEVATED FIRE DANGER IS LIKELY SUNDAY AND MONDAY NORTH OF
I-90, AND ALONG THE HIGHWAY 14 CORRIDOR.
- STRONG SPRING STORM STILL ON TRACK FOR THE END OF THE WEEK
AND START OF NEXT WEEKEND. THIS STORM MAY BRING ALL ASPECTS OF
SPRING WEATHER TO THE REGION INCLUDING THUNDERSTORMS, HIGH
WINDS, AND EVEN SNOW.
- NEAR 100% PROBABILITIES OF PRECIPITATION WITH THIS SYSTEM,
WITH PROBABILITIES OVER 70% FOR MEASURABLE SNOW AND >50%
PROBABILITIES OF NEAR ADVISORY LEVEL WINDS. HOWEVER
CONFIDENCE ON HOW EXACT DETAILS AND AMOUNTS PAN OUT REMAINS
LOW.
DISCUSSION
ISSUED AT 311 AM CDT SUN MAR 9 2025
THIS MORNING: CIRRUS CONTINUES TO SPILL INTO THE PLAINS EARLY
SUNDAY MORNING, WITH A LIGHT MIXY WIND HOLDING TEMPERATURES ABOVE
NORMAL ESPECIALLY OVER ANY ELEVATED GROUNDS. THERE REMAINS A VERY
OUTSIDE CHANCE (LESS THAN 30%) OF VALLEY/RIVER FOG WHERE THE
BOUNDARY LAYER DECOUPLES AND TEMPERATURES COULD FALL INTO THE 20S.
SUNDAY: A VERY WARM DAY IS EXPECTED THROUGHOUT THE REGION DESPITE
THE CONTINUED PRESENCE OF HIGH-LVL CIRRUS DURING THE DAY. A WEAK
SURFACE TROUGH PUSHES EAST THROUGH THE AREA THIS MORNING, ALLOWING A
FAVORABLE WESTERLY DOWNSLOPE WIND TO DEVELOP. AS A RESULT, WE'LL
SEE BOTH TEMPERATURES SOAR TOWARDS THE 60S, BUT ALSO DEW POINTS MIX
DOWN INTO THE 20S. HAVE MIXED IN SOME HRRR/RAP DEW POINTS. FOR FIRE
WEATHER CONCERNS PLEASE SEE SEPARATE DISCUSSION. WE'LL LIKELY MELT
WHAT'S LEFT OF THE SNOW ALONG THE MO RIVER VALLEY, BUT THE WET
GROUND MAY BE ENOUGH TO HOLD BACK TEMPERATURES SLIGHTLY.
TONIGHT: WINDS REMAIN LIGHT, BUT WITH PERSISTENT WESTERLY FLOW AND
EMBEDDED VORTICITY WITHIN THAT MID-UPR FLOW, HIGH CLOUDS ARE LIKELY
TO PERSIST. SOME DECOUPLING OF THE BOUNDARY LAYER WILL AGAIN BE
POSSIBLE BY MONDAY MORNING OWING TO AN ADDITIONAL RISK OF VALLEY
FOG. OTHERWISE LOWS STAY NEAR TO ABOVE NORMAL.
MONDAY-TUESDAY: BROAD MID-LVL RIDGING REMAINS IN PLACE MONDAY,
ALLOWING PERSISTENT WESTERLY TO SOUTHWESTERLY SURFACE WINDS TO
CONTINUE. A LOW-LVL THERMAL RIDGE WILL BE CENTERED OVER THE
TRI- STATE AREA WITH 850MB TEMPERATURES NEAR +13C AND 925MB
TEMPERATURES NEAR +17C. WE SHOULD SEE TEMPERATURES CLIMB WELL
INTO THE 60S IN MANY LOCATIONS WITH PROBABILITIES OF HIGHS IN
THE 70S APPROACHING >80% NEAR HURON AND SIOUX CITY. ONCE AGAIN
THE DRY WESTERLY SURFACE FLOW LEADS TO LOWERING DEW POINTS, AND
WHILE THE RAP/HRRR MAY BE A BIT TOO LOW WITH DEW POINTS IN THE
TEENS, THE POTENTIAL DOES EXIST. A MID-LVL TROUGH DROPPING
THROUGH SOUTHERN CANADA PUSHES AN COLD FRONT SOUTHWARD FAIRLY
AGGRESSIVELY MONDAY EVENING INTO EARLY TUESDAY. SOUNDINGS ALL
SUGGEST WINDS AT THE TOP OF THE MIXED LAYER APPROACHING 40
KNOTS, SO HAVE PUSHED FORECAST WINDS TOWARDS THE 90TH PERCENTILE
(AOA 35 KNOTS). TUESDAY WILL BE THE COOLEST DAY OF THE WORK
WEEK AS HIGH PRESSURE MOVES INTO THE WESTERN GREAT LAKES. HIGHS
WILL STILL RISE INTO THE MID TO UPPER 40S IN MOST LOCATIONS.
WEDNESDAY-THURSDAY: BROAD MID-LVL RIDGING CONTINUES THROUGH THE
MIDDLE OF THE WEEK AS ANY 925:850 MB TEMPERATURES ARE PUSHED
NORTHWARD INTO CANADA. LIGHT SOUTHERLY WINDS, PLENTY OF SUNSHINE,
AND WARMING LOW-LVL TEMPS FORCE HIGHS WEDNESDAY INTO THE 60S. A VERY
WARM OVERNIGHT SHOULD ALLOW TEMPERATURES TO CLIMB EVEN HIGHER
THURSDAY. AS 850MB TEMPERATURES RISE INTO THE +14-15C RANGE EARLY
THURSDAY (NEAR THE 90TH PERCENTILE OF CLIMATOLOGY FOR MID-MARCH) THE
PROBABILITIES OF 70+ DEGREE SURFACE TEMPERATURES BREAK THE 60%
THRESHOLD OVER THE ENTIRE CWA AND APPROACH 80% ALONG THE MISSOURI
RIVER. TEMPERATURES MAY NOT BREAK RECORDS, BUT THEY'LL CERTAINLY COME
WITHIN A COUPLE DEGREES.
FRIDAY-SATURDAY: OBVIOUSLY EYES ARE FOCUSED ON A BIG COLORADO LOW
THAT WILL SWING NORTHWARD INTO THE PLAINS FRIDAY AND SATURDAY.
GENERALLY, MEDIUM RANGE MODEL GUIDANCE IS IN GOOD AGREEMENT FOR A
STORM 6+ DAYS AWAY. CLIMATOLOGY SUGGESTS THAT AN UPPER LOW TRACKING
FROM THE PANHANDLE TO CENTRAL IOWA WOULD BRING RISKS OF ALL TYPES OF
WEATHER TO THE CENTRAL US, FROM THUNDERSTORMS, TO HIGH WINDS, AND AN
INCREASING LIKELIHOOD OF A TROWAL OF MODERATE SNOW ON THE
WESTERN FLANK OF THE LOW. THE DEVIL IS IN THE DETAILS HOWEVER,
TO WHICH EVEN A 100 MILE DEVIATION IN TRACK WILL HAVE LARGE
SCALE IMPACTS ON LOCAL CONDITIONS. ENSEMBLE PROBABILITIES STILL
FOCUS 90%+ PROBABILITIES FOR PRECIPITATION BEGINNING LATE FRIDAY
AND FRIDAY NIGHT, LIKELY IN THE FORM OF ELEVATED CONVECTION.
THEN HIGH POP RETURN INTO SATURDAY AS TROWAL MOVES THROUGH. FROM
THAT POINT FORWARD THOUGH CONFIDENCE DECREASES AS SPREAD GROWS
IN THE TRACK OF A POTENTIAL 980MB (OR LOWER) SURFACE LOW THAT
SITS WELL OUTSIDE THE 30 YEAR CFSR CLIMATOLOGY AROUND MID-
MARCH. ON THE COLD SIDE OF THE STORM, LREF PROBABILITIES SUGGEST
UPWARDS OF 50% PROBABILITIES FOR 3" OF SNOW FOCUSED ALONG AND
WEST OF THE JAMES RIVER AND 70% PROBABILITIES OF MEASURABLE SNOW
IN MOST AREAS. STAY TUNED THROUGH THE DAYS AHEAD.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1026 PM CST SAT MAR 8 2025
PRIMARILY VFR CONDITIONS EXPECTED THROUGH THE PERIOD. THE ONE
POTENTIAL EXCEPTION IS AGAIN THE LOW END (<20%) POTENTIAL FOR
SOME PATCHY VALLEY FOG. INCREASING UPPER LEVEL CLOUDS THROUGH
THE OVERNIGHT MAY VERY WELL MITIGATE THIS THREAT.
OTHERWISE, WESTERLY WINDS WILL INCREASE THROUGH THE LATE MORNING
HOURS SUNDAY, GUSTING AS HIGH AS 20-25 KTS DURING THE
AFTERNOON.
FIRE WEATHER
ISSUED AT 311 AM CDT SUN MAR 9 2025
RISING TEMPERATURES ACROSS PORTIONS OF CENTRAL AND NORTHERN SOUTH
DAKOTA THIS AFTERNOON WILL COINCIDE WITH A SHARP FALL IN DEW
POINTS. RELATIVE HUMIDITY VALUES MAY FALL NEAR OR JUST BELOW 25%
IN THE FAR NORTHWESTERN CORNER OF THE CWA NEAR HURON TO
CHAMBERLAIN BY MID-AFTERNOON. WINDS HOWEVER ARE MORE UNCERTAIN
AS SUSTAINED WINDS AND GUSTS ONLY PEAK NEAR RED FLAG CRITERIA
FOR A BRIEF TIME THIS AFTERNOON. ALL THAT SAID, GIVEN THE
BREVITY OF THE CONDITIONS WILL HOLD OFF ON ANY RED FLAG WARNING.
MONDAY WILL BE ANOTHER DAY WITH VERY HIGH FIRE DANGER ESPECIALLY
IN AREAS NORTH OF I-90. HIGH TEMPERATURES CLIMB EVEN FURTHER
TOWARDS THE 70 DEGREE MARK, WITH AFTERNOON MIX-DOWN OF DEW
POINTS INTO THE 20S. WINDS WILL HOWEVER BE ANOTHER MARGINAL
SETUP AS WE'LL AGAIN FLIRT WITH RED FLAG CRITERIA IN MOST AREAS
NORTH OF I-90, BUT VERY BRIEFLY. FOR NOW, WILL CONTINUE TO
ADVERTISE ELEVATED CONDITIONS AND CONTINUE TO MONITOR FOR THE
POTENTIAL FOR STRONGER WINDS.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...DUX
AVIATION...KALIN
FIRE WEATHER...DUX
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