850
FXUS63 KFSD 312321
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
621 PM CDT SAT MAY 31 2025
KEY MESSAGES
- CANADIAN WILDFIRE SMOKE CONTINUES TO FILTER IN THROUGH THE
WEEKEND. SOME GROUND LEVEL SMOKE AND REDUCED AIR QUALITY
CONTINUES TONIGHT, WITH MORE WIDESPREAD IMPACTS SUNDAY.
CONDITIONS BEGIN TO IMPROVE SUNDAY NIGHT.
- THUNDERSTORM RISKS RETURN MONDAY AFTERNOON INTO MONDAY NIGHT.
SCATTERED SEVERE STORMS ARE POSSIBLE ALONG AND WEST OF A TRACY
TO SIOUX FALLS TO YANKTON LINE. RISKS INCLUDE LARGE HAIL AND
LOCALIZED SEVERE WIND.
DISCUSSION
ISSUED AT 251 PM CDT SAT MAY 31 2025
CURRENTS THROUGH SUNDAY NIGHT: SHOWERS AND ISOLATED THUNDERSTORMS
CONTINUE TO PIVOT AROUND THE EASTERN SIDE OF THE MID/UPPER LEVEL
WAVE MOVING THROUGH SOUTH CENTRAL SD AND NORTHERN NE - FOCUSING THE
SHOWERS ACROSS SOUTH CENTRAL SD INTO THE SOUTHERN JAMES RIVER
VALLEY. THIS SHOULD EXIT THE AREA BY MID TO LATE THIS EVENING.
WILDFIRE SMOKE ALOFT AND AT THE SURFACE CONTINUES TO ADVECT INTO THE
AREA, WITH VISIBILITY NEAR THE US HWY 14 CORRIDOR AND NORTHWARD
OCCASIONALLY DROPPING TO 2 MILES OR LESS. THOSE WHO ARE SENSITIVE TO
SMOKE SHOULD LIMIT EXPOSURE. TEMPERATURES HAVE WARMED INTO THE UPPER
70S TO LOWER 80S FOR MOST LOCATIONS. NORTHWESTERLY WIND GUSTS AROUND
20 TO 25 MPH THIS AFTERNOON AND EVENING TAPER OFF TONIGHT.
SMOKY SKIES CONTINUE THROUGH SUNDAY THANKS TO CONTINUED
NORTHWESTERLY FLOW ALOFT. SURFACE SMOKE BEGINS TO DIMINISH FROM WEST
TO EAST DURING THE AFTERNOON AND EVENING AS LOWER LEVEL WINDS SHIFT
WESTERLY WITH MORE IMPROVEMENT THROUGH THE OVERNIGHT HOURS. REDUCED
VISIBILITY AND AIR QUALITY ARE EXPECTED. DESPITE SMOKY SKIES, EXPECT
WARMER TEMPERATURES ON SUNDAY WITH WARMER TEMPERATURES ALOFT IN THE
RIDGE. HIGHS IN THE 80S TO NEAR 90. LOWS TOMORROW NIGHT IN THE LOWER
60S.
MONDAY-MONDAY NIGHT: ATTENTION TURNS TO THE DEVELOPING MID/UPPER
LEVEL TROUGH IN MT AND SURFACE LOW EJECTING OUT OF WY DURING THE
DAY ON MONDAY. A MID LEVEL WAVE AND UPPER LEVEL JET STREAK EJECT
OUT AHEAD OF THE MAIN TROUGH DURING THE DAY MONDAY. 31.12Z
GUIDANCE HAS COME IN FAIRLY SIMILARLY TIMING WISE TO THE 31.00Z
RUNS, BUT THERE STILL SEEMS TO BE 3-6 HOUR DIFFERENCE BETWEEN THE
FASTEST (CANADIAN) AND SLOWER (GFS/NAM) GUIDANCE. REGARDLESS,
SURFACE COLD FRONT MOVES INTO THE US HIGHWAY 281 CORRIDOR BY MID
AFTERNOON (3-4 PM). AHEAD OF THE FRONT, WE'LL SEE DEW POINTS CLIMB
INTO THE UPPER 50S AND LOWER 60S WITH TEMPS IN THE 80S TO LOWER
90S WITH SOUTHERLY FLOW. THIS LEADS TO INCREASED INSTABILITY AT OR
ABOVE 2000 J/KG. CAP SHOULD BEGIN TO BREAK NEAR THE FRONT THROUGH
THE AFTERNOON. BROAD SYNOPTIC FORCING WITH THE 700MB WAVE AND
UPPER LEVEL JET STREAK INCREASES AS WE HEAD THROUGH THE EVENING.
HOWEVER, IN SPITE OF THE BROADER FORCING MOVING IN, SEVERE RISK
MAY BE RELATIVELY LIMITED IN TIME (3 PM TO 10 PM OR SO) AS
INSTABILITY QUICKLY DROPS OFF LATE IN THE EVENING. GREATEST SEVERE
RISK REMAINS ALONG AND WEST OF A TRACY TO SIOUX FALLS TO YANKTON
LINE. HIGHEST SHEAR VALUES AND LAPSE RATES REMAIN OFFSET FROM THE
HIGHEST INSTABILITY. MAIN THREATS WITH STRONG TO SEVERE STORMS
WOULD BE HAIL TO 1.5" (PING PONG BALL) AND WIND GUSTS TO 65 MPH
WITH DCAPE VALUES AROUND 1000 J/KG.
SHOWERS AND STORMS CONTINUE TO MOVE EAST WITH THE FRONT THROUGH THE
OVERNIGHT HOURS, ALTHOUGH ADDITIONAL DEVELOPMENT BEHIND THE SURFACE
FRONT IS POSSIBLE WITH CONTINUED BROAD SYNOPTIC FORCING AND THE
APPROACH OF THE UPPER LEVEL TROUGH. RAINFALL WITH THIS FRONT SHOULD
BE EFFICIENT WITH FLOW PARALLEL TO THE BOUNDARY AND ROBUST MOISTURE
RETURN. PWAT VALUES AT OR ABOVE 1.5" TO NEAR 2" (WHICH IS IN THE TOP
1% OF VALUES COMPARED TO CLIMATOLOGY). A DEEP WARM CLOUD LAYER NEAR
OR ABOVE 10000 FT AIDS IN WIDESPREAD MODERATE TO HEAVY RAINFALL
POTENTIAL. GIVEN 1 HOURLY FFG RANGING FROM 1.5 TO 2.5+ INCHES IN OUR
AREA - LOWEST IN NORTHWESTERN IA - WIDESPREAD FLASH FLOODING IS NOT
EXPECTED. HOWEVER, HEAVY RAINFALL RATES COULD LEAD TO LOCALIZED
ISSUES ESPECIALLY IN URBAN AREAS. RAINFALL AMOUNTS INTO TUESDAY
MORNING BETWEEN 0.75" AND 2" EXPECTED. CHANCES OF MORE THAN AN INCH
REMAIN MODERATE (40-60%).
TUESDAY: COOLER, CLOUDY, AND RAINY TUESDAY AS THE MID AND UPPER
LEVEL TROUGH CONTINUE TO MOVE EAST AND THE SURFACE FRONT PUSHES
THROUGH IA. HIGHS IN THE 60S TO NEAR 70. BREEZY NORTHWESTERLY WINDS
EXPECTED. ADDITIONAL RAINFALL AMOUNTS OF A TENTH OF AN INCH UP TO AN
INCH - HIGHEST IN SOUTHWESTERN MN AND NORTHWESTERN IA.
WEDNESDAY ONWARD: QUASI ZONAL TO NORTHWESTERLY FLOW DEVELOPS FOR MID
WEEK INTO NEXT WEEKEND. NUMEROUS MID/UPPER LEVEL SHORT WAVES TREK
THROUGH THE NORTHERN AND CENTRAL PLAINS WHICH KEEPS PERIODIC LOW TO
MODERATE (LESS THAN 50%) SHOWER AND STORM CHANCES IN THE FORECAST.
SEVERE STORMS CURRENTLY LOOK UNLIKELY. TEMPERATURES MODERATE CLOSER
TO NORMAL WITH HIGHS IN THE MID AND UPPER 70S AND LOWS IN THE MID
50S.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 620 PM CDT SAT MAY 31 2025
MOSTLY VFR CONDITIONS THROUGH THIS PERIOD, WITH PERIODS OF MVFR AS
PLUMES OF THICKER SMOKE DRIFT THROUGH THE REGION. SMOKE IS EXPECTED
TO CONTINUE TO IMPACT THE REGION THROUGH SUNDAY.
WINDS WILL BECOME LIGHT AND VARIABLE AFTER SUNSET. BY MID-MORNING
WINDS WILL BEGIN TO INCREASE SLIGHTLY AND TAKE ON A SOUTHWESTERLY TO
SOUTHERLY DIRECTION. WINDS REMAIN MOSTLY LIGHT WITH SOME GUSTS TO 15
KTS POSSIBLE WEST OF THE MN/IA/SD BORDER. STRONGEST GUSTS ARE
EXPECTED OVER SOUTH CENTRAL SOUTH DAKOTA, WHERE GUSTS TO 20 KTS ARE
POSSIBLE.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...SG
AVIATION...AJP
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