580
FXUS63 KFSD 221911
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
211 PM CDT SUN JUN 22 2025
KEY MESSAGES
- A FEW SEVERE STORMS WILL BE LIKELY THIS EVENING WEST OF I-29.
THE MAIN THREATS WILL BE PING PONG BALL HAIL AND WIND GUSTS TO
70 MPH. LOCALLY HEAVY RAIN WILL BE A SECONDARY RISK.
- AN ACTIVE PATTERN ALOFT WILL CONTINUE FOR MUCH OF NEXT WEEK.
WHILE SOME UNCERTAINTY REMAINS, THE BETTER CHANCE FOR ISOLATED
SEVERE STORMS AND PATCHY HEAVY RAINFALL WILL BE TUESDAY NIGHT
INTO WEDNESDAY NIGHT. SOME LOCALLY HEAVY RAIN WILL BE
POSSIBLE IN NORTHWEST IA AND NORTHEAST NE MONDAY NIGHT.
DISCUSSION
ISSUED AT 209 PM CDT SUN JUN 22 2025
THE LEAST DAY OF EXTREME HEAT EXPECTED AS A COOL FRONT SPILLS INTO
THE AREA. NORTHWEST IA, NORTHEAST NE AND FAR SOUTHEAST SD WILL
REMAIN IN THIS WARM AND HUMID AIR INTO THE OVERNIGHT HOURS, BUT BY
MONDAY MORNING NORTHWESTERLY WINDS WILL REACH THESE AREAS.
THE MAIN CONCERN CENTERS AROUND SEVERE THUNDERSTORM POTENTIAL. MODEL
SOUNDINGS CONTINUE TO POINT TO A VIGOROUS CAPPING INVERSION THAT
WILL LIKELY HOLD THROUGH THE AFTERNOON. THE LATEST HI RES GUIDANCE
MODEL SOUNDINGS SHOW PARTS OF NORTH CENTRAL NE TRYING TO BREAK
THROUGH THIS CAP AROUND 23Z, WHICH THEN PERCOLATES NORTHWARD JUST
BEHIND THE INCOMING COOL FRONT AS FLOW AROUND 800 MB AND A BIT ABOVE
BACKS A TOUCH. AS THIS FORCING KICKS IN, INSTABILITY WILL LIKELY BE
1500-2000 J/KG WITH ELEVATED DEEP LAYER SHEAR RUNNING ABOUT 40
KNOTS. WITH THE EXPECTED INSTABILITY AND SHEAR, AS WELL AS ABOUT
1500 J/KG DCAPE POTENTIAL, WINDS AROUND 65 MPH AS WELL AS AS WELL
HAIL TO PING PONG BALL WILL BE POSSIBLE. THESE HIGHER END THREATS
WILL BE MOST LIKELY CLOSER TO THE 925-850 MB FRONT WHICH WILL LIKELY
BE FROM ROUGHLY LAKE ANDES TO DE SMET. FATHER WEST OF THIS LOWER
LEVEL FRONT LIFT WILL BE MORE ELEVATED AND WHILE SOME INSTABILITY
AND SHEAR EXIST, THE THREAT SHOULD BE MORE LIMITED TO QUARTER SIZED
HAIL AND 50-60 MPH WINDS. WITH STORMS EXPECTED TO MOVE FAIRLY
QUICKLY NORTHEAST, HEAVY RAINFALL IS NOT EXPECTED, BUT LOCALLY HEAVY
DOWNPOURS AND VERY LOCALIZED HEAVY RAIN WILL BE POSSIBLE.
SHOWERS AND ISOLATED THUNDERSTORMS REMAIN POSSIBLE MOSTLY SOUTH OF I-
90 ON MONDAY. THE MAIN INSTABILITY APPEARS TO BE SUPPRESSED TO THE
SOUTH SO SEVERE WEATHER AND HEAVY RAIN LOOK UNLIKELY. MONDAY NIGHT
APPEARS TO HAVE A SIMILAR SET UP AS A NEW JET MAX FEEDS INTO THE
EXISTING CORRIDOR OF STRONG WINDS ALOFT TO THE WEST. THIS WILL ALLOW
FOR SOME WEAK RIDGING ALOFT LATE MONDAY NIGHT INTO TUESDAY WHICH
SHOULD LIMIT COVERAGE OF ANY ACTIVITY THAT COULD DEVELOP. THE
EXCEPTION MAY BE FARTHER TO THE SOUTH WHERE DEEPER INSTABILITY
EXISTS ACROSS NE/IA AND RETURN FLOW BEGINS TO SET UP ON TUESDAY.
WILL NEED TO KEEP AN EYE ON A SMALL CORRIDOR OF HEAVIER RAIN
POTENTIAL ACROSS NORTHWEST IA.
TUESDAY NIGHT INTO WEDNESDAY NIGHT CONTINUES TO SHOW THE HIGHEST
POTENTIAL FOR A MORE WIDESPREAD RAINFALL AND THUNDERSTORMS.
INSTABILITY IS ON THE MODERATE SIDE WITH ABOUT 1000-1500 J/KG CAPE.
SHEAR IS A BIT DISORGANIZED WITH DECENT SOUTHWEST INFLOW FROM ABOUT
925-850MB, THEN WEAK FLOW FROM ABOUT 700-500MB, THEN A DECENT JET
ALOFT RUNNING ABOUT 40-60 KNOTS. GIVEN EXPECTED STORM MOTION AND
INFLOW SOME TRAINING WILL BE POSSIBLE SO IF WE GET A PERIOD OF HEAVY
RAIN THIS SHOULD BE THE FAVORED TIME FRAME.
THE PERSISTENT UPPER LEVEL JET TO THE WEST BEGINS TO WEAKEN AND
SHIFT EAST ON THURSDAY AND THIS SHOULD TAKE THE BETTER CHANCES FOR
SHOWERS AND STORMS TO THE EAST. IF THE RAIN DOES END UP EAST OF THE
AREA THURSDAY THEN IT SHOULD PROVE TO BE A DECENT DAY WITH HIGHS IN
THE UPPER 70S TO LOWER 80S AND WINDS GENERALLY LESS THAN 15 MPH.
FRIDAY THROUGH SUNDAY AN UPPER LEVEL RIDGE TRIES TO BUILD INTO THE
AREA WITH THE MAIN CORRIDOR OF STRONGER JET LEVEL WINDS WEAKENING
AND SHIFTING NORTH. THIS LEAVES THE AREA IN WEAKER WEST TO SOUTHWEST
FLOW ALOFT WITH POORLY AGREED UPON WEAKER WAVES MOVING THROUGH THIS
FLOW. TEMPERATURES IN THIS PATTERN SHOULD BE NEAR TO A BIT ABOVE
NORMAL WITH A FEW CHANCES FOR SHOWERS AND STORMS.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1239 PM CDT SUN JUN 22 2025
SHOWERS AND THUNDERSTORMS WILL DEVELOP IN CENTRAL SD AROUND
23-0Z, THEN SPREAD NORTHEAST THROUGH THE EVENING AND OVERNIGHT
HOURS. A FEW OF THESE STORMS MAY BE SEVERE. THE BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS BEFORE 6Z WILL BE WEST OF I-29, THEN
AFTER 6Z NEAR AND NORTH OF I-90. SOME MVFR CEILINGS MAY BRIEFLY
FILL IN BEHIND THE SHOWERS AND STORMS BUT OUTSIDE OF THE
THUNDERSTORMS MUCH OF THE PERIOD WILL BE VFR. THE BETTER CHANCE
FOR LOWER CEILINGS WILL BE ACROSS NORTHEAST NE AND NORTHWEST IA.
FSD WATCHES/WARNINGS/ADVISORIES
SD...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR SDZ061-
062-065>071.
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ038>040-
053>056-059-060-063-064.
MN...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR MNZ071-
072-080-081-089-090-097-098.
IA...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR
IAZ001>003-012>014-020>022-031-032.
NE...EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR NEZ013-
014.
DISCUSSION...08
AVIATION...08
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