439
FXUS63 KFSD 200510
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1210 AM CDT WED MAY 20 2026
KEY MESSAGES
- FROST AND FREEZE CONDITIONS ARE EXPECTED TONIGHT INTO EARLY
WEDNESDAY MORNING ACROSS THE AREA - TAKE PRECAUTIONS TO
PROTECT SENSITIVE VEGETATION. FROST/FREEZE HEADLINES GO INTO
EFFECT LATE TONIGHT.
- SCATTERED SHOWERS WILL RETURN WEDNESDAY 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
ENSEMBLES GUIDANCE SUGGESTS UP TO A 10 TO 30 PERCENT CHANCE
FOR A HALF AN INCH OF RAIN DURING THIS TIME.
UPDATE
ISSUED AT 842 PM CDT TUE MAY 19 2026
THE FORECAST REMAINS ON TRACK WITH THE MAIN THE FOCUS BEING ON THE
FROST/FREEZE POTENTIAL TONIGHT. WITH A SURFACE HIGH CONTINUING TO
PROGRESS THROUGH THE NORTHERN PLAINS, WE'RE ALREADY STARTING TO SEE
LIGHTER WINDS TAKE HOLD ACROSS THE AREA THIS EVENING. THIS COMBINED
WITH RAPIDLY COOLING TEMPERATURES AND A SMALLER DEW POINT DEPRESSION
OVERNIGHT WILL LIKELY LEAD TO FROST/FREEZE CONDITIONS ESPECIALLY IN
OUR NORTHWESTERN ZONES. WITH THIS IN MIND, WE'RE STILL ON TRACK FOR
SCATTERED AREAS OF FROST WITH PATCHY AREAS OF WIDESPREAD FREEZE
MAINLY ALONG THE HIGHWAY-14 CORRIDOR SO MAKE SURE TO COVER/BRING IN
ANY SENSITIVE VEGETATION! OTHERWISE, A CHILLY START IS AHEAD AS MOST
AREAS WILL WAKE UP TO TEMPERATURES IN THE LOW TO MID 30S TO START
WEDNESDAY. HOWEVER, THESE CONDITIONS WON'T STAY FOR LONG AS
SOUTHERLY/SOUTHEASTERLY WINDS HELP TEMPERATURES IMPROVE TO THE 60S
FOR THE DAY. LASTLY, CAN'T COMPLETELY RULE OUT A FEW SCATTERED
SHOWERS MAINLY WEST OF THE JAMES RIVER VALLEY BY WEDNESDAY
AFTERNOON. NONETHELESS, ANY ACCUMULATIONS WOULD BE LIGHT AT BEST.
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 WEDNESDAY FOR SDZ050-054>071.
FREEZE WARNING UNTIL 8 AM CDT WEDNESDAY FOR SDZ038>040-052-053.
MN...FROST ADVISORY UNTIL 8 AM CDT WEDNESDAY FOR MNZ071-072-080-081-
089-090-097-098.
IA...FROST ADVISORY UNTIL 8 AM CDT WEDNESDAY FOR IAZ001>003-012>014-
020>022-031-032.
NE...FROST ADVISORY UNTIL 8 AM CDT WEDNESDAY FOR NEZ013-014.
UPDATE...05
DISCUSSION...08
AVIATION...05
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