434
FXUS63 KFSD 240754
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
254 AM CDT SAT OCT 24 2026
KEY MESSAGES
- BREEZY WITH FALLING TEMPERATURES TODAY: A PUSH OF STRONGER
WINDS ARRIVES IN SOUTH-CENTRAL SOUTH DAKOTA NEAR/JUST AFTER
SUNRISE. GUSTS WITH THIS WILL INCREASE TO 35-40 MPH FOR A
BRIEF PERIOD.
- COOLER WITH SCATTERED WEEKEND RAIN: A SLOW-MOVING FRONT WILL
BRING INCREASED CLOUDS AND OCCASIONAL RAIN THIS WEEKEND.
TEMPERATURES WILL BE NOTABLY COOLER (40S/50S) BY SUNDAY.
- SIGNIFICANT RAINFALL LIKELY MONDAY-TUESDAY: A LARGE MULTI-DAY
SYSTEM WILL BRING WIDESPREAD RAIN TO START THE NEW WORK WEEK.
CONFIDENCE IN AMOUNTS OVER 1" THROUGH TUESDAY MORNING REMAIN
HIGH.
- ACTIVE WEATHER CONTINUES: A SECOND FAST MOVING SYSTEM MAY
BRING RAIN CHANCES BACK BY TUESDAY NIGHT AND WEDNESDAY, WITH
TEMPERATURES NEAR SEASONAL NORMALS.
UPDATE
ISSUED AT 253 AM CDT SAT OCT 24 2026
SCATTERED SHOWERS AND VERY ISOLATED THUNDERSTORMS ARE EXPECTED TODAY
AS MID LEVEL MOISTURE STREAMS NORTHWARD. THIS IS IN RESPONSE TO A
STRONG NORTH/SOUTH ORIENTED JET THAT WILL INCREASE THROUGH THE DAY.
WEAK (300-500 J/KG CAPE) INSTABILITY WILL BRING THE THREAT FOR A
LITTLE LIGHTNING AND VERY BRIEF DOWNPOURS. THE BETTER CHANCES FOR
THIS WILL BE NEAR AND WEST OF I-29. WITH THE FREEZING LEVEL AROUND
11 KFT, EVEN SMALL HAIL IS NOT EXPECTED. WHILE MOST AREAS WILL ONLY
SEE LIGHTER ACCUMULATIONS, SOME SPOTTY LOCATIONS COULD SEE 0.10" TO
0.25".
WHILE THERE WILL LIKELY BE A BIT OF A LULL IN SHOWERY ACTIVITY FROM
ABOUT MID AFTERNOON INTO THE EARLY OVERNIGHT HOURS, THE NEXT WAVE
LOOKS TO MOVE INTO CENTRAL SD LATER TONIGHT INTO SUNDAY. LOW AND MID
LEVEL WINDS RESPOND TO THIS WAVE, INCREASING WARM AIR ADVECTION AND
DEEPENING MOISTURE. ONCE AGAIN, THE BETTER CHANCES APPEAR TO REMAIN
MOSTLY WEST OF I-29.
THE AREA BEGINS TO LOSE SATURATION IN THE DGZ ON SUNDAY AS THIS WAVE
MOVES NORTH THROUGH CENTRAL SD. SATURATION REMAINS MOST PERSISTENT
WEST OF HIGHWAY 81, WITH NORTHWEST IA SEEING THE LARGEST STRUGGLE TO
SATURATE ALOFT. SOME VERY WEAK ELEVATED INSTABILITY IN NORTHWEST IA
LATER SUNDAY AFTERNOON MAY ALLOW FOR A SPOTTY SHOWER OR TWO.
MONDAY MAY END UP COOLER THAN FORECAST WITH LOW LEVEL COOL AIR
LIKELY REMAINING LOCKED IN WITH RAINFALL OCCURRING. INTERESTING TO
NOTE THAT THE NAM, WHILE AN OUTLIER, WOULD POTENTIALLY BRING A
LITTLE MIXED PRECIPITATION OR SNOW TO THE HURON AND CHAMBERLAIN
AREAS MONDAY AFTERNOON/EVENING. MOST OF THE OTHER DATA HANGS ON TO
SLIGHTLY WARMER TEMPERATURES, BUT NOT BY A LOT. SLIGHTLY WARMER LOW
LEVEL TEMPERATURES WOULD ALSO BE SUPPORTED BY THE EXITING OF THE
RIGHT ENTRANCE REGION OF THE NORTHERN JET AND THE INCREASE OF THE
SOUTHERN JET DURING THIS TIME.
TO PUT ALL OF THIS INTO PERSPECTIVE, THE LATEST NAM AND RRFS TOTAL
QPF THROUGH TUESDAY MORNING PLACES ABOUT 1-2.5" OVER SOUTH CENTRAL
INTO EAST CENTRAL SD AND WHILE THE EC ENSEMBLE, GEFS AND CANADIAN
ENSEMBLE ARE A BIT MORE BROAD WITH THEIR OUTPUT, THE LOCATION IS
VERY SIMILAR, IF NOT A TOUCH FARTHER WEST. A FAIRLY TIGHT GRADIENT
FROM HIGHER AMOUNTS TO LOWER AMOUNTS WILL LIKELY SET UP FROM ABOUT
VERMILLION TO WINDOM. ALL IN ALL THIS TRACKS FAIRLY WELL WITH THE
MID LEVEL WAVES (700-500MB) OVER THE NEXT FEW DAYS.
DISCUSSION
ISSUED AT 1218 PM CDT FRI OCT 23 2026
THIS AFTERNOON: WINDS CONTINUE TO INCREASE EARLY THIS AFTERNOON WITH
OBSERVED GUSTS BETWEEN 30 AND 45 MPH. TEMPERATURES CONTINUE TO WARM
INTO THE 70S, AND POTENTIAL FOR SOME HIGHS IN THE 80S REMAIN
POSSIBLE ALONG AND WEST OF THE JAMES RIVER VALLEY. HOWEVER, A
PERSISTENT MID-UPR CLOUD DECK MAY LIMIT THE CLIMB THIS AFTERNOON.
OUT IN WESTERN SOUTH DAKOTA, WE'RE BEGINNING TO SEE THE FIRST SIGNS
OF A FRONTAL BOUNDARY FORMING THAT WILL GRADUALLY MOVE EASTWARD
OVERNIGHT. THE FIRE DANGER REMAINS VERY HIGH THIS AFTERNOON,
ESPECIALLY FOR AGRICULTURAL AREAS, PLEASE SEE SEPARATE DISCUSSION.
TONIGHT: AN ELONGATED UPPER TROUGH STRETCHING ACROSS THE ROCKIES AND
INTO SOUTHERN CALIFORNIA WILL BEGIN TO STRETCH AND SPLIT IN TWO
OVERNIGHT. NORTHERN ENERGY TRACKING EASTWARD ACROSS SOUTHERN CANADA
WILL BE STRONG ENOUGH TO NUDGE THE AFOREMENTIONED SURFACE BOUNDARY
INTO THE I-29 CORRIDOR BY MID-MORNIGN SATURDAY. AHEAD OF THIS
BOUNDARY, CONVERGENCE ON A 40 KNOT LLJ AND THE ARRIVAL OF A MID-LVL
VORTICITY MAXIMA SHOULD BE ENOUGH TO ALLOW ISOLATED TO SCATTERED
SHOWERS TO DEVELOP AND AND AHEAD OF THIS BOUNDARY. MUCAPE MAY BE AS
HIGH AS 300 J/KG AFTER 3AM, SO HAVE INCREASED POTTHUNDER TO AT LEAST
SUGGEST ISOLATED LIGHTNING STRIKES INTO MID-MORNING.
SATURDAY-SUNDAY: WHILE NORTHERN STREAM ENERGY MOVES EASTWARD ACROSS
CANADA, A LARGE UPPER TROUGH WILL REMAIN OVER THE FOUR CORNERS
REGION THROUGH THE WEEKEND. OVERHEAD AND CLOSER TO HOME, THE
AFOREMENTIONED SURFACE BOUNDARY WILL LINGER ACROSS THE TRI-STATE
AREA THIS WEEKEND. THIS FRONT, STACKED ON TOP BY A LOW-LVL FRONTAL
ZONE, AS WELL AS SOMEWHAT PERSISTENT DIVERGENCE FROM THE RIGHT
ENTRANCE REGION OF AN UPPER JET, WILL KEEP SCATTERED RAIN CHANCES
AND QUITE A BIT OF CLOUD COVER THROUGH THE AREA DURING THE WEEKEND.
NOW THE DEGREE OF RAIN COVERAGE IS STILL UP IN THE AIR, GIVEN
SOMEWHAT DIFFUSE AND TRANSIENT LIFT AT TIMES, BUT ALSO SOME SUB
CLOUD DRY AIR THAT COULD LINGER. SO WILL CONTINUE TO ADVERTISE
A NARROW STRIPE OF LOW TO MID-RANGE POPS THAT WILL FLUCTUATE
NORTH AND SOUTH WITH THE MOVEMENT OF THE LOW-LVL BAROCLINIC
ZONE.
TEMPERATURES WILL BE QUITE TRICKY ON SATURDAY AS THE FRONT BISECTING
THE CWA COULD LEAD TO A LARGE TEMPERATURE DISCREPANCY FROM
HURON TO STORM LAKE. 12Z GUIDANCE HAS TRENDED DOWNWARDS WITH
HIGHS SLIGHTLY, SO BLENDED IN SHORT TERM GUIDANCE TO ACCOUNT FOR
TRENDS THE NBM MAY NOT HAVE CAUGHT ONTO YET. THERE SEEMS TO BE
MUCH MORE CONSISTENCY IN GUIDANCE THAT COOLER AIR MAY SINK
FURTHER SOUTH BEHIND THE FRONT FOR SUNDAY. WITH A PERSISTENT AND
COOL NORTHEAST SURFACE FLOW IN THE CWA, HIGHS MAY STRUGGLE TO
BREAK THE 50S IN PORTIONS OF THE CWA WITH THE WARMEST HIGHS NEAR
HIGHWAY 20.
MONDAY-TUESDAY: SLIGHT DISCREPANCIES IN MEDIUM RANGE GUIDANCE ON
THURSDAY HAVE RESOLVED SOMEWHAT THIS MORNING. THE LARGE UPPER
TROUGH IN THE FOUR CORNER BEGINS TO EJECT NORTHEAST LATE SUNDAY
INTO MONDAY, AND WILL BEGIN TO ENHANCED WARM ADVECTION
NORTHWARD AND INCREASE THE INTENSITY OF THE LOW-LVL FRONTAL ZONE
THROUGH THE CWA BY MONDAY MORNING. WE'LL HAVE TO WATCH FOR ANY
POTENTIAL INSTABILITY ARRIVAL, BUT FAIRLY WIDESPREAD MODERATE
RAIN MAY BEGIN TO FORM MONDAY MORNING AND GRADUALLY RETREAT
NORTHWARD AS THE UPPER TROUGH ENTERS THE PLAINS.
LATEST GFS GUIDANCE HAS SHIFTED THE TRACK OF THE UPPER LOW SLIGHTLY
FURTHER NORTHWEST FROM THE NEBRASKA PANHANDLE INTO CENTRAL SOUTH
DAKOTA BY MONDAY NIGHT, CLOSELY RESEMBLING THE LATEST ECMWF RUNS. AI
BASED MODELS ARE ALSO VERY SIMILAR IN THEIR TRACK OF THIS UPPER WAVE
(PERHAPS A BIT FURTHER SOUTH THAN DETERMINISTIC RUNS), SUGGESTING
WIDESPREAD RAIN WILL CONTINUE INTO TUESDAY MORNING AS THE SYNOPTIC
TROUGH PASSES.
ALL-IN-ALL, THIS MULTI-DAY RAIN EVENT IS EXPECTED TO BRING RAIN
TO NEARLY THE ENTIRE REGION, AND IN SOME CASES, MEANINGFUL
RAINFALL TOTALS. THE LATEST PROBABILITIES FROM THE ECE/GEFS FOR
>0.50" ARE ALL NEAR 100% BY TUESDAY MORNING, WITH 1.0"
PROBABILITIES >80%, AND PROBABILITIES FOR 2-3" OF RAIN AROUND
30%. THE LOCATION MAY CHANGE, BUT THE AREA WITH THE GREATEST
POTENTIAL FOR THE HIGHEST TOTALS MAY FALL BETWEEN I-90 AND THE
MISSOURI RIVER WEST OF I-29.
MONDAY'S HIGH TEMPERATURES WILL BE HIGHLY DEPENDING ON THE TRACK OF
THE UPPER LOW AND ASSOCIATED SURFACE CYCLOGENESIS AND LOW TRACK.
AREAS STUCK UNDER MODERATE RAIN MAY BE IN THE 40S, WITH AREAS WHERE
RAIN LIFTS NORTH COULD RISE INTO THE 50S.
WEDNESDAY-THURSDAY: IT APPEARS A SECOND SYSTEM MAY RACE THROUGH THE
NORTHERN US ON THE HEELS OF MONDAY/TUESDAY UPPER TROUGH BY TUESDAY
NIGHT AND WEDNESDAY. WE'LL SEE HOW QUICKLY MOISTURE CAN WORK IT'S
WAY BACK NORTHWARD, BUT THIS SECOND SYSTEM ALSO POSES A REASONABLE
RISK FOR RAINFALL IN THE MIDDLE OF THE WEEK ALONG WITH A SLIGHT
UPWARDS BUMP IN TEMPERATURES TOWARDS NORMAL.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1102 PM CDT FRI OCT 23 2026
SHOWERS WILL INCREASE IN COVERAGE THROUGH THE MORNING HOURS ON
SATURDAY, WITH ISOLATED THUNDERSTORMS POSSIBLE. ANY THREAT FOR
THUNDER SHOULD END BY THE LATE MORNING HOURS, BUT SCATTERED
SHOWERS DO LOOK TO CONTINUE AT TIMES THROUGH THE END OF THE
PERIOD. SOME OF THE SHOWERS THIS MORNING WILL BRING CEILINGS
DOWN TO 2-3 KFT, BUT OTHERWISE VFR CONDITIONS ARE EXPECTED.
A COLD FRONT MOVES ACROSS THE AREA TODAY, WHICH WILL TURN WINDS TO
THE NORTHWEST ONCE IT MOVES THROUGH. IT WILL ALSO BRING A BRIEF
SURGE IN WIND GUSTS TOWARDS 35+ KTS IN SOUTH-CENTRAL SOUTH
DAKOTA IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE NEAR AND JUST
AFTER SUNRISE.
CLIMATE
ISSUED AT 1218 PM CDT FRI OCT 23 2026
A VERY WARM DAY WILL STILL BRING THE POTENTIAL FOR RECORD HIGH
MINIMUM TEMPERATURES ON FRIDAY. SIOUX CITY AND SIOUX FALLS HAVE
ALREADY DROPPED LOWER THAN THEIR RECORD FOR THE DATE, HOWEVER HURON
DROPPED TO 62, SO POTENTIAL FOR TYING OR BREAKING THIS RECORD
REMAINS POSSIBLE.
OCTOBER 23:
KFSD: 60/1963
KSUX: 65/1899
KHON: 52/1963
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...08
DISCUSSION...DUX
AVIATION...SAMET
CLIMATE...DUX
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