980
FXUS63 KFSD 121953
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
253 PM CDT THU MAR 12 2026
KEY MESSAGES
- A RED FLAG WARNING REMAINS IN EFFECT UNTIL 9 PM TONIGHT DUE TO RELATIVE
HUMIDITY VALUES DROPPING BELOW 30% AND STRONG WIND GUSTS OF
30-45 MPH.
- A MARGINAL (LEVEL 1 OF 5) RISK FOR ISOLATED TO SCATTERED RAIN SHOWERS
TO THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING. THE
GREATEST RISK IS WIND GUSTS OF 60+ MPH.
- A HIGH WIND WARNING IS IN EFFECT TONIGHT FROM 7 PM THIS
EVENING UNTIL 7 AM FRIDAY MORNING. NORTHWEST GUSTS COULD REACH
55-65 MPH WITH ISOLATED GUSTS UP TO 75 MPH POSSIBLE.
- SNOW LOOKS TO RETURN ON SATURDAY IN A WEAK BAND. HOWEVER, A
STRONGER SYSTEM IS EXPECTED TO BEGIN TO IMPACT THE AREA
SATURDAY EVENING. THIS SYSTEM WILL PERSIST THROUGH THE
ENTIRETY OF SUNDAY BEFORE FINALLY EXITING THE AREA BY EARLY
MONDAY MORNING.
- STRONG WINDS AND HEAVY SNOW ARE IN STORE FOR THIS SYSTEM.
THUS, A WINTER STORM WATCH FOR BLIZZARD CONDITIONS HAS BEEN
ISSUED FOR LOCATIONS ALONG AND NORTHEAST OF A LINE FROM
CHAMBERLAIN, SOUTH DAKOTA TO BERESFORD, SOUTH DAKOTA TO STORM
LAKE, IOWA LINE. THE WATCH IS IN EFFECT FROM SATURDAY EVENING
INTO MONDAY MORNING.
DISCUSSION
ISSUED AT 250 PM CDT THU MAR 12 2026
AN ACTIVE PATTERN IS AHEAD WITH CONFIDENCE FOR SIGNIFICANTLY
IMPACTFUL WEATHER INCREASING. LOOKING ALOFT AT GOES WATER VAPOR WE
CAN SEE THE FLOW ALOFT IS NORTHWESTERLY WITH A 140-150 KT JET
STREAK. THE EXIT REGION OF WHICH IS LOCATED OVER THE TRI-STATE AREA
THROUGH THIS AFTERNOON AND OVERNIGHT. THE RESULTING WIND DIVERGENCE
ALOFT WILL FURTHER ENHANCE WINDS IN THE LLJ AS SURFACE CONVERGENCE
INCREASES AND PRESSURE FALLS AHEAD OF AN INCOMING CLIPPER SYSTEM. AS
WE BEGIN TO MIX HIGHER INTO THE BOUNDARY LAYER TODAY WE WILL TAP
INTO THAT 30-40 KT LLJ. GUSTS AT THE SURFACE WILL INCREASE THROUGH
THE AFTERNOON AS A RESULT, REACHING 30-45 MPH.
THE CLIPPER SYSTEM PLACES US IN A STRONG WAA REGIME THIS AFTERNOON.
HOWEVER, THERE ARE A FEW DETAILS THAT MAY WORK TO LIMIT AFTERNOON
HIGHS. CLOUDS CONTINUE TO FLOW IN FROM THE NORTHWEST, AND HAVE
ADVANCED FURTHER SOUTH FASTER THAN PREVIOUSLY ANTICIPATED. THERE IS
ALSO A CHANCE FOR ISOLATED TO SCATTERED RAIN SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING, ROUGHLY BETWEEN 3PM TO
9PM. SOUNDINGS INDICATE A VERY DRY SUBCLOUD LAYER, WHICH WILL LIMIT
HOW MUCH ACTUALLY REACHES THE GROUND. HOWEVER, DUE TO A 10 DEGREE C
DEWPOINT TEMPERATURE DEPRESSION, EVAPORATIVE COOLING AS RAIN FALLS
THROUGH THE DRY LAYER MAY PRODUCED SEVERE WIND GUSTS OF 60+ MPH.
THIS IS OUTLINED IN THE SPC DAY 1 MARGINAL (LEVEL 1 OF 5) OUTLOOK.
CONSIDERING THIS HAVE DECIDED TO GO WITH THE SLIGHTLY COOLER NBM
HIGHS FOR THIS AFTERNOON. ALONG AND SOUTH OF A ROUGH LINE FROM HURON
TO STORM LAKE HIGHS WILL RANGE FROM THE LOW TO UPPER 60S, WARMEST
ALONG THE SOUTHERN MISSOURI RIVER COUNTIES. THIS AREA IS ALSO
EXPECTED TO SEE THE LOWEST RELATIVE HUMIDITY VALUES, LESS THAN 30%.
TO THE NORTH OF THAT LINE HIGHS WILL BE IN THE 50S WITH HIGHER
RELATIVE HUMIDITY VALUES. THOUGH WE HAVE SOME LINGERING
SNOW/SNOWMELT ON THE GROUND FROM YESTERDAY, AND THE COOLER HIGHS
TODAY, THE LOW HUMIDITY AND VERY STRONG WINDS KEEP GRASSLAND FIRE
DANGER IN THE VERY HIGH TO EXTREME CATEGORIES FOR THIS
AFTERNOON. SEE THE FIRE WEATHER DISCUSSION BELOW FOR MORE
DETAILS.
OUR NEXT PERIOD OF CONCERN COMES THIS EVENING AND OVERNIGHT AS THE
CLIPPER SYSTEM DROPS SOUTHEAST INTO MINNESOTA. THE SPG CONTINUES TO
TIGHTEN AS PRESSURE FALLS AHEAD OF THE COLD FRONT. THE LLJ ENHANCES
AS DIVERGENCE ALOFT INCREASES. TEMPERATURES IN THE MID-LEVELS DROP
RAPIDLY 6-10 DEGREES C BEHIND THE FRONT. ALL THESE FACTORS WILL WORK
TOGETHER TO PRODUCE VERY STRONG WINDS BEGINNING LATER THIS AFTERNOON
AND CONTINUING THROUGH FRIDAY MORNING. BY 6PM CDT TONIGHT GUSTS EAST
OF I-29 WILL BE BETWEEN 25-35 MPH. AREAS TO THE WEST WILL BE SEEING
GUSTS 35-45 MPH. AS WE CONTINUE INTO THE EVENING GUSTS CONTINUE
TO INCREASE AND SPREAD SOUTHEASTWARD. WIDESPREAD GUSTS OF 55-65
MPH ARE EXPECTED WITH ISOLATED GUSTS UP TO 75 MPH POSSIBLE.
WINDS REMAIN STRONG THROUGH 4-6 AM CDT WHEN THEY WILL BEGIN TO
GRADUALLY TAPER OFF THROUGH FRIDAY MORNING, BECOMING LIGHT IN
THE AFTERNOON. AFTERNOON HIGHS WILL BE COOLER THANKS TO THE
NORTHWESTERLY WINDS BRINING IN COLD AIR, REACHING ONLY THE MID
30S TO 40S.
SATURDAY WILL BEGIN WITH LIGHT SNOW BEGINNING TO FALL DURING THE
EARLY MORNING HOURS AS WARM AIR ADVECTION (WAA) STRENGTHENS ALOFT,
TIGHTENING THE ELEVATED FRONTAL TEMPERATURE GRADIENT AND ALSO
STRENGTHEN THE FRONTOGENESIS (FGEN) ALONG IT. THE DENDRITIC GROWTH
ZONE (DGZ) WILL ALSO BE SATURATED WITH SUFFICIENT OMEGA (UPWARD
MOTION) IN IT TO SUPPORT A BAND OF SNOW. THE GOOD NEWS ABOUT THIS
BAND IS THAT NOT EXPECTED TO LAST LONG AS THE FGEN WILL BE WEAKENING
DURING THE MORNING HOURS. LIGHT SNOWFALL IS EXPECTED WITH THIS BAND
WHICH LOOKS TO FALL ACROSS NEAR AND NORTH OF I-90. SATURDAY
AFTERNOON WILL BE MORE ON THE DRY SIDE AS THE UPPER LEVEL WAVE
RESPONSIBLE FOR ADDITIONAL IMPACTS WILL BE PUSHING IN FROM THE
NORTHERN ROCKIES. HIGH TEMPERATURES LOOK TO WARM TO THE 30S TO UP TO
AROUND 50F DURING THE AFTERNOON TIMEFRAME THOUGH DEPENDING ON HOW
MUCH SNOW FALLS DURING THE MORNING HOURS, HIGHS TEMPERATURES COULD
COME DOWN A BIT.
CHANCES FOR SNOW WILL BE INCREASING SATURDAY EVENING AS WAA
RESTRENGTHENS ALOFT. THIS IN TURN WILL RE-TIGHTEN THE TEMPERATURES
GRADIENT AND THUS RESTRENGTHEN THE FGEN ALONG THE ELEVATED FRONT.
THIS WILL BE THE MAIN SHOW AS STRONG QG ASCENT RESIDES IN THE RIGHT
ENTRANCE REGION OF AN UPPER LEVEL JET. SNOW WILL EXPAND IN COVERAGE
THROUGH THE REST OF THE EVENING AND ENTIRE OVERNIGHT HOURS. THERE
COULD BE A SMALL AREA OF MIXED PRECIPITATION ON THE LEADING EDGE OF
THE BAND OF SNOW AS THE WAA JUST BARELY PUSHES TEMPERATURES ABOVE
FREEZING ALOFT. THE STRONG FRONT WILL TRANSLATE SOUTHWARDS AFTER
BEGINNING AROUND THE HIGHWAY-14 CORRIDOR. THIS WILL QUICKLY COOL THE
WARMED TEMPERATURES, TURNING ANY MIXED PRECIPITATION BACK OVER TO
SNOW. THE STRONGEST ASCENT WILL COME DURING THE OVERNIGHT HOURS AND
INTO EARLY SUNDAY MORNING WHERE THE LATEST DETERMINISTIC GUIDANCE
SHOWS STRONG FGEN AROUND 700 MB ALONG WITH LOW STABILITY AND
NEGATIVE EQUIVALENT POTENTIAL VORTICITY (EPV) VALUES ABOVE THE
FRONT. THUS, THE BULK OF THE SNOW LOOKS TO FALL DURING THIS PERIOD
OF TIME. AT THE SAME TIME, WINDS WILL BE STRENGTHENING AS SNOW FALL
RATES INCREASE. GUSTS WILL BE OUT OF THE EAST/NORTHEAST WITH GUSTS
STRENGTHENING UP TO 30-40 MPH THROUGHOUT THE NIGHT. WITH SUCH STRONG
WINDS IN PLACE AS SNOW IS FALLING, BLOWING SNOW IS EXPECTED WITH THE
FALLING SNOW. THE BEST FORCING FOR ASCENT WILL BE SLIDING EASTWARDS
THROUGHOUT THE MORNING HOURS ON SATURDAY. THIS WILL GRADUALLY END
SNOWFALL ACROSS THE AREA FROM NORTHWEST TO SOUTHEAST. THOUGH LATEST
TRENDS KEEP SNOW CHANCES GOING THROUGH THE AFTERNOON TIMEFRAME.
WINDS WILL TURN TO OUT OF THE NORTH DURING THIS PERIOD OF TIME WITH
GUSTS FURTHER INCREASING UP TO ABOUT 50 MPH. SNOW WILL HAVE THE
POTENTIAL TO BLOW AROUND AFTER SNOW IS DONE FALLING. THUS, BLOWING
SNOW LOOKS TO PERSIST FOR THE REST OF SATURDAY EVEN AFTER THE SNOW
FINISHES FALLING. THUS, HAVE DECIDED TO ISSUE A WINTER STORM WATCH
FOR BLIZZARD CONDITIONS. THE WATCH IS IN EFFECT FROM SATURDAY
EVENING THROUGH MONDAY MORNING AS THE WEAKENING WINDS WILL STILL
RESULT IN SOME BLOWING SNOW THROUGH SUNDAY NIGHT. SNOWFALL AMOUNTS
AT THIS TIME LOOK TO BE IMPACTFUL WITH THE ENSEMBLES SHOWING A 40-
90% CHANCE FOR SNOWFALL TOTALS TO EXCEED 6 INCHES MAINLY ALONG AND
NORTHEAST OF A CHAMBERLAIN, SOUTH DAKOTA TO BERESFORD, SOUTH DAKOTA
TO STORM LAKE, IOWA LINE. THE HIGHEST PROBABILITIES LIE ACROSS
SOUTHWEST MINNESOTA. THE ENSEMBLES SPREAD INCREASES UP TO A FOOT OF
SNOW WHERE THE PROBABILITIES SPAN FROM A 20-60% CHANCE, HIGHEST
AGAIN ACROSS SOUTHWEST MINNESOTA. THIS COMBINATION OF WIND AND
SNOWFALL LOOKS TO BRING THE MOST IMPACTFUL WINTER STORM OF THE
SEASON TO THE AREA. WHILE DETAILS CAN CHANGE HEADING INTO THIS
EVENT, PLEASE CONTINUE TO MONITOR THE LATEST FORECAST FOR THE MOST
UP TO DATE INFORMATION.
THE REST OF THE NEXT WEEK LOOKS TO BEGIN ON THE COLD SIDE AND SLOWLY
WARM THROUGHOUT THE WEEK. THERE COULD BE ADDITIONAL CHANCES FOR SNOW
DURING THE MIDDLE OF THE WEEK BUT DETAILS ARE UNCERTAIN.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1257 PM CDT THU MAR 12 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR THIS PERIOD. ISOLATED TO
SCATTERED SHOWERS TO THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON.
STORMS MUST CONTEND WITH A VERY DRY SUBCLOUD LAYER, LIMITING HOW
MUCH MOISTURE WE RECEIVE AT THE SURFACE. STILL, SOME RAIN IS LIKELY
TO MAKE IT THROUGH BUT IT WILL BE VERY SPOTTY IN NATURE AND CONFINED
MOSTLY ALONG AND NORTH OF I-90. IN ADDITION, THANKS TO THE DRY
LAYER, THERE IS POTENTIAL THAT STORMS COULD PRODUCE VERY STRONG DOWN
DRAFT WIND GUSTS IN EXCESS OF 52 KTS. STORMS ARE EXPECTED TO EXIT TO
THE EAST THIS EVENING.
AT THE SAME TIME STORMS ARE EXITING, A CLIPPER SYSTEM WILL PAST JUST
TO THE NORTH OF THE REGION. AS IT DOES SO, SURFACE WINDS WILL
INCREASE DRASTICALLY BEGINNING THIS AFTERNOON AND CONTINUING
OVERNIGHT INTO FRIDAY MORNING. FREQUENT GUSTS OF 45-55 KTS WILL BE
WIDESPREAD WITH GUSTS UP TO 62 KTS POSSIBLE. SURFACE WINDS ARE
EXPECTED TO VERY GRADUALLY DECREASE THROUGH THE AFTERNOON FRIDAY.
LOW LEVEL WIND SHEAR IS EXPECTED AT ALL THREE TAF SITES AS THE
SURFACE COLD FRONT PASSES THROUGH. SHEAR IS EXPECTED TO BEGIN AROUND
00Z FRIDAY AT KHON AND PROGRESS RAPIDLY SOUTHEAST THROUGH KFSD AND
KSUX OVER THE NEXT HOUR OR TWO. SHEAR IS EXPECTED TO RELAX AFTER 06Z
FRIDAY.
FIRE WEATHER
ISSUED AT 250 PM CDT THU MAR 12 2026
SOUTHWESTERLY TO WESTERLY WINDS GUSTING 30-45 MPH COUPLED WITH LOW
MINIMUM RELATIVE HUMIDITY HAS RESULTED IN GRASSLAND FIRE DANGER
REACHING THE VERY HIGH TO EXTREME CATEGORY. MINIMUM RELATIVE
HUMIDITY VALUES ARE EXPECTED TO FALL TO 25-35% ALONG AND SOUTH OF A
LINE FROM HURON TO STORM LAKE LINE.
HIGH TEMPERATURES HAVE TRENDED SLIGHTLY COOLER WITH THIS
FORECAST PACKAGE. DESPITE THAT, THE VERY DRY AIR AND STRONG
WINDS COULD STILL ALLOW FOR RAPID FIRE INTENSIFICATION. AS SUCH,
THE RED FLAG WARNING UNTIL 9 PM CDT TODAY REMAINS IN GOOD
SHAPE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...RED FLAG WARNING UNTIL 9 PM CDT THIS EVENING FOR SDZ038-050-
052>055-057>071.
HIGH WIND WARNING FROM 9 PM THIS EVENING TO 7 AM CDT FRIDAY
FOR SDZ066>071.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
MORNING FOR SDZ040-056-062-067.
HIGH WIND WARNING FROM 7 PM THIS EVENING TO 7 AM CDT FRIDAY
FOR SDZ038>040-050-052>065.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH LATE SUNDAY
NIGHT FOR SDZ038-039-052>055-057>061.
MN...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
MORNING FOR MNZ071-072-080-081-089-090-097-098.
HIGH WIND WARNING FROM 7 PM THIS EVENING TO 7 AM CDT FRIDAY
FOR MNZ071-072-080-081-089-090-097-098.
IA...RED FLAG WARNING UNTIL 9 PM CDT THIS EVENING FOR IAZ001>003-
012>014-020>022-031-032.
HIGH WIND WARNING FROM 9 PM THIS EVENING TO 7 AM CDT FRIDAY
FOR IAZ001>003-012>014-020>022-031-032.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
MORNING FOR IAZ001>003-012>014-021-022.
NE...RED FLAG WARNING UNTIL 9 PM CDT THIS EVENING FOR NEZ013-014.
HIGH WIND WARNING FROM 9 PM THIS EVENING TO 7 AM CDT FRIDAY
FOR NEZ013-014.
DISCUSSION...MEYERS/AJP
AVIATION...AJP
FIRE WEATHER...AJP
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