075
FXUS63 KFSD 111134
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
634 AM CDT TUE MAR 11 2025
KEY MESSAGES
- A STRONG SPRING STORM REMAINS ON TRACK FOR FRIDAY THROUGH
SATURDAY. MULTIPLE HAZARDS ARE POSSIBLE, FROM THUNDERSTORMS
TO HIGH WINDS AND AREAS OF SNOW. CONTINUE TO MONITOR THE
LATEST FORECAST FOR THE MOST UP TO DATE INFORMATION.
- NEAR 100% PROBABILITY OF PRECIPITATION WITH THE LATE WEEK
SYSTEM, WITH MODERATE (40-50%) PROBABILITY OF RAIN/LIQUID
EQUIVALENT AMOUNTS EXCEEDING 0.50". SNOWFALL AMOUNTS ARE LOW
CONFIDENCE DUE TO UNCERTAINTY IN TIMING OF TRANSITION. HOWEVER
WITH EXPECTED STRONG WINDS SATURDAY, ANY SNOW COULD RESULT IN
DIFFICULT TRAVEL.
- ABOVE AVERAGE TEMPERATURES REMAIN ON TRACK TO CONTINUE THROUGH
MUCH OF THE UPCOMING WEEK. HIGH TEMPERATURES INTO THE 60S AND
70S ARE LIKELY FOR THE SECOND HALF OF THIS WEEK, WITH ELEVATED
TO NEAR-CRITICAL FIRE WEATHER CONCERNS RETURNING THURSDAY.
DISCUSSION
ISSUED AT 425 AM CDT TUE MAR 11 2025
TODAY-TONIGHT: A COOLER DAY ON TAP TODAY IN THE WAKE OF A COLD
FRONT WHICH PUSHED SOUTH ACROSS THE REGION OVERNIGHT. WHILE
STILL ABOVE NORMAL, HIGHS TODAY WILL BE 20-30F COLDER THAN
YESTERDAY WITH READINGS TOPPING OUT IN THE 40S. WARM ADVECTION
BEGINS TO SET IN ACROSS WESTERN PARTS OF THE FORECAST AREA BY
LATE THIS AFTERNOON, EXPANDING EAST TONIGHT. THIS SHOULD KEEP
LOWS TONIGHT ON THE MILD SIDE, GENERALLY A FEW DEGREES EITHER
SIDE OF 30F.
WEDNESDAY-THURSDAY: UPPER LEVEL RIDGING BEGINS TO WORK EAST
INTO THE NORTHERN PLAINS MID-WEEK, WITH 850-925MB TEMPERATURES
CLIMBING INTO THE DOUBLE DIGITS BY THURSDAY. WEAK NORTHEAST TO
EAST WINDS ON WEDNESDAY COULD LIMIT MIXING, THOUGH MORE ABUNDANT
SUNSHINE SHOULD HELP TEMPERATURES CLIMB INTO THE 60S. THURSDAY
WILL BE THE WARMEST DAY, WITH ALL DETERMINISTIC MODELS SHOWING
925MB TEMPERATURES PUSHING 20C INTO OUR SOUTHWEST COUNTIES BY
LATE IN THE DAY. SOUTH-SOUTHWEST LOW LEVEL FLOW FAVORS DEEPER
MIXING, WITH THESE TEMPERATURES SUPPORTIVE OF HIGHS IN THE
UPPER 70S, PERHAPS REACHING 80F IN ISOLATED LOCATIONS. LATEST
NBM IS SLIGHTLY BELOW ITS 25TH PERCENTILE ACROSS OUR WESTERN
COUNTIES, WITH THE NBM 50TH PERCENTILE MORE REPRESENTATIVE OF
ABOVE THINKING. THUS HAVE BUMPED HIGHS THURSDAY TOWARD THE NBM
50TH PERCENTILE IN COORDINATION WITH NEIGHBORING OFFICES.
THE WARM TEMPERATURES ALONG WITH A CONTINUED DRY AIR MASS AND
BREEZY SOUTHERLY FLOW GUSTING 25 TO 35 MPH LEADS TO WIDESPREAD
GRASSLAND FIRE DANGER INDEX IN THE VERY HIGH CATEGORY THURSDAY
AFTERNOON. LOCATIONS WEST OF THE JAMES RIVER VALLEY, WHERE LOW
LEVEL FLOW MAY TURN A BIT MORE WEST OF SOUTH, COULD SEE DRIER
AIR MIX TO THE SURFACE, RESULTING IN MINIMUM HUMIDITY LEVELS OF
20-25 PERCENT. WILL HAVE TO WATCH THIS AREA FOR NEAR CRITICAL
FIRE WEATHER CONDITIONS AND POSSIBLE HEADLINES.
FRIDAY-SATURDAY NIGHT: GREATEST ATTENTION REMAINS FOCUSED ON
THE STRONG SPRING STORM SYSTEM WHICH IS SLATED TO IMPACT THE
REGION LATE IN THE WEEK. SIMILAR TO THE PAST SEVERAL DAYS,
NAEFS/ECMWF MAINTAIN A SYSTEM FALLING BELOW THE MINIMUM OF
CLIMATOLOGY FOR THIS TIME OF YEAR AS IT SWINGS NORTHEAST FROM
THE CENTRAL PLAINS INTO MINNESOTA. ANOMALOUSLY STRONG SOUTH-
SOUTHWEST FLOW AHEAD OF THE SYSTEM EXTENDS THROUGHOUT THE DEPTH
OF THE ATMOSPHERE, WITH ENSEMBLES SHOWING WIND SPEEDS EXCEEDING
THE 90TH PERCENTILE ON FRIDAY. WHILE THE LOW LEVEL FLOW DOES
HAVE SOME PULL FROM THE WESTERN GULF, SOME QUESTION REGARDING
HOW FAR WEST THE DEEPER MOISTURE WILL EXTEND. STILL, SEEING
POTENTIAL FOR MUCAPE IN EXCESS OF 500J/KG WRAPPING INTO OUR
EASTERN COUNTIES BY LATE FRIDAY INTO FRIDAY EVENING. SHEAR IS ON
THE WEAKER SIDE THIS FAR WEST, BUT DEPENDING ON THE TRACK OF
THE SYSTEM, CANNOT RULE OUT AN ISOLATED STRONGER STORM WITH BOTH
NSSL GEFS AND CSU MACHINE LEARNING PROBABILITIES INDICATING AT
LEAST 5% PROBABILITIES FOR SEVERE WEATHER IN OUR FORECAST AREA
THIS PERIOD.
FOR LATER FRIDAY NIGHT, WHILE WE ARE SEEING SOME NARROWING OF
THE MODEL CONSENSUS, LINGERING DIFFERENCES IN TRACK AND TIMING
OF THE MAIN SURFACE LOW LEAD TO UNCERTAINTY IN THE STRENGTH AND
LOCATION OF THE COLDER AIR WRAPPING INTO THE BACKSIDE OF THE
SYSTEM LATER FRIDAY NIGHT/SATURDAY. THIS WILL IMPACT EVENTUAL
SNOWFALL AMOUNTS, THOUGH ENSEMBLES CONTINUE TO SHOW HIGH (>80%)
PROBABILITIES FOR MEASURABLE SNOWFALL FOR MUCH OF OUR FORECAST
AREA AT SOME POINT LATE FRIDAY NIGHT INTO SATURDAY NIGHT, WITH
MODERATE (40-60%) PROBABILITIES OF AN INCH OR MORE. CURRENTLY,
ENSEMBLE PROBABILITY OF ADVISORY LEVEL SNOWFALL (>3") IS ON THE
LOW SIDE (20-30%). HOWEVER, SIMILAR TO THE STRONG WINDS AHEAD OF
THE SYSTEM FRIDAY, EQUALLY STRONG OR STRONGER WINDS ARE LIKELY
ON THE BACKSIDE SATURDAY MORNING, WITH GOOD MODEL CONSENSUS IN
850MB WINDS EXCEEDING 50KT ACROSS EASTERN SD AT 12Z SATURDAY.
THUS, REGARDLESS OF SNOWFALL TOTALS, ANYONE WITH TRAVEL PLANS
SHOULD ANTICIPATE A PERIOD OF DIFFICULT TRAVEL ON SATURDAY, WITH
THE WINTER STORM SEVERITY INDEX SHOWING A 40-50% PROBABILITY OF
MODERATE IMPACTS IN AREAS WEST OF I-29.
PRECIPITATION IS CURRENTLY EXPECTED TO LIFT NORTHEAST OF THE
AREA BY SATURDAY EVENING, WITH WINDS SLOWLY DECREASING THROUGH
THE NIGHT.
SUNDAY-MONDAY: MILD AIR ALOFT QUICKLY RETURNS TO THE REGION BY
MONDAY, THOUGH THE DEGREE TO WHICH WE SEE THAT WARMING AT THE
SURFACE WILL DEPEND ON EVENTUAL SNOWFALL TOTALS.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 634 AM CDT TUE MAR 11 2025
SPOTTY MVFR-IFR LEVEL STRATUS (900-1500FT AGL) IS FLOATING
AROUND ALONG AND NORTH OF HIGHWAY 14. DO NOT EXPECT SUB-VFR
CEILINGS TO DEVELOP AT KHON, BUT COULD SEE FEW-SCT015 OR LOWER
FOR A FEW HOURS EARLY IN THE PERIOD.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THIS TAF PERIOD.
NORTH WINDS REMAIN BREEZY WITH GUSTS 15-20KT EAST OF I-29 AT
11Z, BUT THIS GUSTINESS IS EXPECTED TO DIMINISH BY MID-MORNING.
NORTH WINDS THEN GRADUALLY BECOME EAST TO SOUTHEAST AT OR BELOW
12KT THROUGH THE PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...JH
AVIATION...JH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page