088
FXUS63 KFSD 200746
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
246 AM CDT WED MAY 20 2026
KEY MESSAGES
- FROST AND FREEZE CONDITIONS CONTINUE THIS MORNING WITH
TEMPERATURES FALLING INTO THE 30S ACROSS THE AREA. FREEZE
WARNING AND FROST ADVISORY REMAIN IN EFFECT UNTIL 8 AM CDT.
- VERY PATCHY FOG THIS MORNING MAY REDUCE VISIBILITY TO BELOW
ONE MILE AT TIMES. FOG DISSIPATES BY MID MORNING.
- SCATTERED SHOWERS RETURN THIS AFTERNOON MAINLY WEST OF THE
JAMES RIVER VALLEY WITH LIGHT ACCUMULATIONS EXPECTED.
- COOLER CONDITIONS CONTINUE THIS WEEK. ANOTHER ROUND OF SHOWERS
AND ISOLATED THUNDERSTORMS IS EXPECTED FROM THURSDAY AFTERNOON
THROUGH FRIDAY. SEVERE WEATHER NOT EXPECTED. HOWEVER, SOME
ENSEMBLE GUIDANCE SUGGESTS UP TO A 40 PERCENT CHANCE FOR A
HALF AN INCH OF RAIN DURING THIS TIME.
UPDATE
ISSUED AT 245 AM CDT WED MAY 20 2026
CALM WINDS AND MOSTLY CLEAR SKIES ARE ALLOWING TEMPERATURES TO
PLUMMET INTO THE MID 30S TO LOWER 40S, WITH LOWS STILL EXPECTED TO
FALL INTO THE LOWER/MID 30S ACROSS THE AREA. FREEZE WARNING FOR
PORTIONS OF THE US HWY 14 CORRIDOR AND FROST ADVISORY ELSEWHERE
REMAIN ON TRACK. A COUPLE OF SITES ACROSS NORTHWESTERN IA AND
SOUTHEASTERN SD HAVE DEVELOPED FOG EARLY THIS MORNING, LEADING TO
VISIBILITY BELOW ONE MILE AT TIMES. EXPECT FOG TO LIFT BY MID
MORNING.
FORECAST FOR THE REST OF THE DAY REMAINS ON TRACK AS THE NEXT MID
LEVEL WAVES MOVES OUT OF NE. CAMS STILL SHOW SOME SHOWERS WEST OF
THE JAMES RIVER LATER TODAY INTO TONIGHT, WITH SOME WEAK INSTABILITY
THROUGH THE SATURATED LAYER. DRY SUB CLOUD LAYER WITH BASES AROUND
5K FT MIGHT LIMIT HOW MUCH REACHES THE SURFACE, ESPECIALLY WITH
SURFACE HIGH PRESSURE MEANDERING EAST TODAY. HIGHS WARM INTO THE
LOWER/MID 60S WITH INCREASING CLOUDS. THIS IS ABOUT 10 DEGREES BELOW
NORMAL FOR LATE MAY.
DISCUSSION
ISSUED AT 1245 PM CDT TUE MAY 19 2026
COOL HIGH PRESSURE SETTLES INTO THE AREA TONIGHT AND WILL BRING A
VERY GOOD CHANCE FOR TEMPERATURES TALL TO OR BELOW 35 FOR MOST OF
THE AREA WITH TEMPERATURES AT OR BELOW FREEZING POSSIBLE NORTH OF I-
90. THUS A FREEZE WARNING IS IN PLACE FOR HIGHWAY 14 AND NEARBY
LOCATIONS IN SD WITH A FROST ADVISORY FOR THE REMAINDER OF THE AREA.
ISOLATED POCKETS OF FOG WILL BE POSSIBLE EARLY WEDNESDAY MORNING BUT
AT THIS TIME IT DOES NOT APPEAR AS THOUGH IT WILL BECOME MORE
WIDESPREAD.
A WEAK WAVE WILL MOVE THROUGH THE AREA ON WEDNESDAY WHICH COULD
BRING A FEW SPRINKLES BUT OVERALL SHOULD MAINLY BE AN INCREASE IN
MID LEVEL CLOUDS. OTHERWISE SLIGHTLY MORE MILD TEMPERATURES ARE
EXPECTED AS SOUTHERLY FLOW DEVELOPS AND BRINGS HIGHS BACK INTO THE
60S FOR MOST LOCATIONS.
ANOTHER WEAK WAVE MOVES ACROSS NE ON THURSDAY AND COULD BRING SOME
LIGHT SHOWERS TO THE MISSOURI RIVER CORRIDOR INTO NORTHWEST IA.
PRECIPITATION AMOUNTS WILL BE LIGHT AS MOISTURE WITH THE SYSTEM IS
VERY LIMITED.
A BIT STRONGER AND MORE NEGATIVELY TILTED SYSTEM WILL SWING THROUGH
ON FRIDAY BRINGING THE NEXT BEST CHANCE FOR RAINFALL. INSTABILITY
VERY MINOR WITH CAPE VALUES GENERALLY 500 J/KG OR LESS. THE MODEL
SOUNDINGS DO INDICATE THE POTENTIAL FOR SOME EFFICIENT RAINFALL
HOWEVER SO MAYBE SOME HALF INCH OR SO AMOUNTS WILL BE POSSIBLE. THE
LATEST ENSEMBLE OUTPUT INDICATING ABOUT A 10 TO 30 PERCENT CHANCE
FOR MORE THAN A HALF AN INCH AND THE LATEST NAM IS INDICATING A
COUPLE OF AREAS WITH MORE THAN A HALF AN INCH. LONG STORY SHORT,
ONLY MINOR IMPACTS EXPECTED WITH NO SEVERE WEATHER.
AS THIS SYSTEM MOVES NORTHEAST AND OUT OF THE AREA A FEW LINGERING
SHOWERS WILL BE POSSIBLE ON SATURDAY, BUT WARMER TEMPERATURES WILL
BEGIN TO WORK INTO THE REGION. SUNDAY THROUGH THE MIDDLE OF NEXT
WEEK WILL SEE TROUGHINESS TO THE WEST AND RIDGING TO THE EAST,
LEAVING THE AREA IN WARMER SOUTHERLY FLOW. WHILE THERE IS VERY
LITTLE AGREEMENT, THERE SHOULD BE A COUPLE OF WEAKER WAVES THAT COULD
BRING SHOWERS AND THUNDERSTORMS TO THE AREA, BUT FOR NOW CONFIDENCE
IS TOO LOW TO INCLUDE IN THE FORECAST. OTHERWISE HIGHS SHOULD BE IN
THE 80S WITH LOWS MAINLY IN THE 50S MONDAY THROUGH WEDNESDAY.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1200 AM CDT WED MAY 20 2026
VFR CONDITIONS WILL CONTINUE THIS TAF PERIOD. MOSTLY CLEAR
CONDITIONS WILL LIKELY PERSIST THROUGHOUT THE FIRST HALF OF THE
DAY BEFORE CLOUDS COVER INCREASES FOR THE SOUTH WITH OUR NEXT
WAVE. BESIDES A FEW SCATTERED SHOWERS MAINLY WEST OF THE JAMES
RIVER VALLEY, MOST AREAS SHOULD REMAIN DRY. OTHERWISE, LIGHT AND
VARIABLE WINDS WILL BECOME MORE SOUTHERLY WITH THE BREEZIEST
CONDITIONS WEST OF I-29.
FSD WATCHES/WARNINGS/ADVISORIES
SD...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR SDZ050-054>071.
FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR SDZ038>040-052-
053.
MN...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR MNZ071-072-080-
081-089-090-097-098.
IA...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR IAZ001>003-
012>014-020>022-031-032.
NE...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR NEZ013-014.
UPDATE...SG
DISCUSSION...08
AVIATION...05
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