483
FXUS63 KFSD 190802
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
302 AM CDT TUE MAY 19 2026
KEY MESSAGES
- POCKETS OF DRIZZLE AND ISOLATED SHOWERS CONTINUE EARLY THIS
MORNING. SPRINKLES ARE POSSIBLE THIS AFTERNOON ACROSS
SOUTWESTERN MINNESOTA.
- 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.
- COOLER CONDITIONS CONTINUE THIS WEEK. DRY WEATHER EXPECTED MID
WEEK. ANOTHER ROUND OF STORMS WILL BE POSSIBLE FROM THURSDAY
AFTERNOON THROUGH FRIDAY.
UPDATE
ISSUED AT 301 AM CDT TUE MAY 19 2026
AN AREA OF SHOWERS/SPRINKLES IS MOVING SOUTH INTO THE JAMES RIVER
VALLEY EARLY THIS FROM NORTHEASTERN SD. ADDITIONALLY, DRIZZLE HAS
CONTINUE TO TAPER OFF, DESPITE MOST OF THE AREA UNDER LOW STRATUS.
STRATUS CONTINUES THROUGH THE DAY, WITH HIGHS ONLY WARMING INTO THE
50S ONCE AGAIN. MAY SEE SOME DIURNALLY DRIVEN SPRINKLES FOR
SOUTHWESTERN MN AND ADJACENT AREAS OF SD AND IA TODAY AS WE HAVE A
BIT OF WEAK INSTABILITY IN THE SATURATED STRATUS LAYER.
OTHER CHANGE FOR THE NEXT 24 HOURS WAS THE ISSUANCE OF FREEZE
WARNINGS AND FROST ADVISORIES FOR TONIGHT INTO EARLY WEDNESDAY
MORNING. CLEARING SKIES WITH THE SURFACE HIGH PRESSURE SLIDING
OVERHEAD AND LIGHT WINDS LATE TUESDAY THROUGH EARLY WEDNESDAY SHOULD
ALLOW FOR EFFICIENT RADIATIONAL COOLING. WE'LL ALSO SEE AT LEAST WEAK
CAA AT 925MB THROUGH THE NIGHT. WE PROBABLY WON'T BE AS EFFICIENT AS
A COUPLE WEEKS AGO THANKS TO RECENT RAINFALL, BUT THINK THAT
TEMPERATURES STILL FALL LOW ENOUGH INTO THE 30S TO LEAD TO
WIDESPREAD IMPACTS TO VEGETATION. FREEZE WARNING WAS LIMITED TO THE
SD SIDE OF THE US HWY 14 CORRIDOR AND INTO CENTRAL SD, WHERE
CONFIDENCE IS HIGHER IN LOWS FALLING INTO THE LOWER 30S.
DISCUSSION
ISSUED AT 1258 PM CDT MON MAY 18 2026
EARLY THIS AFTERNOON THE SURFACE TO 925 MB FRONT WAS ACROSS SOUTHERN
NE INTO SOUTHERN IA. GIVEN THE MARGINAL STRENGTH OF THE INCOMING
WAVE, THIS BOUNDARY SHOULD NOT LIFT FAR ENOUGH NORTH AND WEST
BY LATE AFTERNOON TO GET INTO THE AREA. THIS SHOULD LIMIT ANY
WIND AND TORNADO THREATS AND KEEP THEM OFF TO THE SOUTHEAST.
HOWEVER, SOME ELEVATED HAILERS WILL REMAIN POSSIBLE ACROSS
MAINLY NORTHWEST IA AS ELEVATED CAPE VALUES RAMP UP TO ABOUT
1000-1500 J/KG AND DEEP LAYER SHEAR IS A FAIRLY STRONG,
UNIDIRECTIONAL 40-50 KNOTS. THIS WOULD BE LIFTING A PARCEL FROM
ABOVE THE STRATUS LAYER, WHICH WOULD LIKELY BE IN ABOUT THE
800-750MB LAYER. THE BETTER CHANCES WILL BE FROM ABOUT 5 PM TO 9
PM.
AFTER THIS WAVE PUSHES THE REMAINING INSTABILITY OUT OF THE AREA
THIS EVENING, DRY AND COOL CONDITIONS ARE EXPECTED FOR TUESDAY AND
WEDNESDAY. THE ONLY CONCERNS ON THESE TWO DAYS WILL BE THE POTENTIAL
FOR FROST AND FREEZE CONDITIONS, MOSTLY NORTH OF I-90, AS SURFACE
HIGH PRESSURE IS IN PLACE. ANOTHER WEAKER WAVE MOVES THROUGH THE
AREA ON WEDNESDAY BUT FOR NOW THIS APPEARS TO BRING MAINLY MID LEVEL
CLOUD COVER.
THE NEXT BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS WILL COME
THURSDAY NIGHT INTO FRIDAY NIGHT. AT THIS TIME SEVERE WEATHER LOOKS
TO REMAIN ISOLATED AS MODEL INSTABILITY FIELDS ARE HINTING AT 1000
J/KG CAPE OR LESS FOR THE MOST PART.
ONCE THIS WAVE PASSES A WARMING TREND SHOULD MOVE IN AS FLAT RIDGING
ALOFT DEVELOPS AHEAD OF A DEEPENING LOW PRESSURE IN THE NORTHERN
ROCKIES. SATURDAY SHOULD BE MILD, LIKELY IN THE 70S, WHILE SUNDAY
SEES THE BETTER CHANCE TO WARM INTO THE 80S.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1158 PM CDT MON MAY 18 2026
MAINLY MVFR TO IFR CONDITIONS WILL CONTINUE THIS TAF PERIOD.
TAKING A LOOK AT SATELLITE IMAGERY, AREAS OF MVFR TO LIFR
STRATUS CONTINUE TO BLANKET THE AREA WITH A FEW POCKETS OF
DRIZZLE. WHILE THESE CONDITIONS WILL LIKELY PERSIST IN THE
OVERNIGHT HOURS, SHOULD SEE GRADUAL IMPROVEMENTS FROM WEST TO
EAST BY MID-MORNING ON TUESDAY RETURNING THINGS BACK TO VFR
CONDITIONS. LASTLY, BREEZY NORTHWESTERLY WINDS WILL PERSIST
INTERMITTENTLY THROUGH TUESDAY EVENING TO END THE TAF PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...FROST ADVISORY FROM 1 AM TO 8 AM CDT WEDNESDAY FOR SDZ050-
054>071.
FREEZE WARNING FROM 1 AM TO 8 AM CDT WEDNESDAY FOR SDZ038>040-
052-053.
MN...FROST ADVISORY FROM 1 AM TO 8 AM CDT WEDNESDAY FOR MNZ071-072-
080-081-089-090-097-098.
IA...FROST ADVISORY FROM 1 AM TO 8 AM CDT WEDNESDAY FOR IAZ001>003-
012>014-020>022-031-032.
NE...FROST ADVISORY FROM 1 AM TO 8 AM CDT WEDNESDAY FOR NEZ013-014.
UPDATE...SG
DISCUSSION...08
AVIATION...05
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