466
FXUS63 KFSD 190559
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1259 AM CDT SUN JUL 19 2026
KEY MESSAGES
- HOTTER CONDITIONS REMAIN ON TRACK FOR SUNDAY AND LIKELY
MONDAY WHERE HEAT INDICES COULD CLIMB INTO THE LOW 100S. A
HEAT ADVISORY HAS BEEN ISSUED FOR LOCATIONS ALONG AND WEST OF
THE JAMES RIVER ON SUNDAY FROM 1PM TO 9PM.
- TEMPORARY REDUCTIONS IN VISIBILITY WILL BE POSSIBLE THROUGH
SUNDAY ESPECIALLY ACROSS SOUTHWESTERN MN DUE TO WILDFIRE
SMOKE. ANY SENSITIVE GROUPS SHOULD CONTINUE MONITORING THEIR
LOCAL AIR QUALITY.
- CHANCES FOR SHOWERS AND STORMS RETURN TO THE AREA EARLY
TOMORROW MORNING AND PERSIST THROUGH MONDAY. COVERAGE IS NOT
EXPECTED TO BE WIDESPREAD. ISOLATED STRONG TO SEVERE STORMS
ARE POSSIBLE SUNDAY NIGHT AND ON MONDAY.
UPDATE
ISSUED AT 943 PM CDT SAT JUL 18 2026
QUIET CONDITIONS ARE EXPECTED THROUGH MOST OF THE OVERNIGHT
HOURS AS TEMPERATURES FALL MAINLY INTO THE 60S FOR LOWS SUNDAY
MORNING. WIDELY SCATTERED ELEVATED SHOWERS LOOK TO DEVELOP LATE
TONIGHT INTO EARLY TOMORROW MORNING OVER NORTH-CENTRAL SOUTH
DAKOTA, BUT PERHAPS AS FAR SOUTHEAST AS WHERE THE MISSOURI RIVER
VALLEY AND HIGHWAY 20 INTERSECT. THIS ACTIVITY WILL GRADUALLY
PUSH EASTWARD THROUGH SUNDAY MORNING. INSTABILITY MAY INCREASE
JUST ENOUGH BEFORE THESE SHOWERS ARRIVE THAT A COUPLE OF
THUNDERSTORMS CANNOT BE RULED OUT MAINLY NEAR AND WEST OF THE
JAMES RIVER SUNDAY MORNING, BUT SEVERE WEATHER IS NOT EXPECTED.
THIS ACTIVITY WILL GRADUALLY WEAKEN WITH EASTWARD EXTENT AS IT
RUNS AHEAD OF ANY APPRECIABLE INSTABILITY. THESE SHOWERS WILL
HELP LIMIT US FROM REACHING FULL HEATING POTENTIAL SUNDAY, SO
DID LOWER THE HIGH TEMPERATURE FORECAST BY A COUPLE OF DEGREES;
HOWEVER, THIS COOLING WILL BE OFFSET BY HIGHER DEW POINTS AND
THUS THE CURRENT HEAT ADVISORY REMAINS IN GOOD SHAPE.
AFTER THESE MORNING SHOWERS FADE AND EXIT THE AREA, INSTABILITY WILL
INCREASE BUT THE CAP LOOKS TO BE FIRMLY IN PLACE. THUS,
CURRENTLY NOT EXPECTING TO SEE NEW THUNDERSTORM DEVELOPMENT
SUNDAY AFTERNOON AND EARLY EVENING. THE MAIN CONCERN FOR
STRONGER THUNDERSTORMS WILL COME OVERNIGHT AS STORMS DEVELOP TO
OUR NORTH AND WEST AND MOVE TOWARDS PARTS OF OUR AREA, MORE ON
THAT THREAT IN THE DISCUSSION BELOW.
DISCUSSION
ISSUED AT 201 PM CDT SAT JUL 18 2026
QUIET CONDITIONS CONTINUE THIS AFTERNOON WITH HIGHS WARMING UP TO
THE 80S. WINDS REMAIN LIGHT OUT OF THE EAST/NORTHEAST, MAKING FOR A
PLEASANT SUMMER DAY. LIGHT CONCENTRATIONS OF SMOKE REMAIN ACROSS THE
AREA. SENSITIVE INDIVIDUALS COULD HAVE SOME ISSUES WITH THE SMOKE
ACROSS THE AREA. WITH THE LIGHT WINDS IN PLACE, THE LIGHT SMOKE
LOOKS TO BE HERE TO STAY. DRY CONDITIONS WILL PERSIST THROUGH THE
REST OF TODAY BUT THINGS WILL CHANGE FOR THE OVERNIGHT HOURS. A COLD
FRONT THAT HAS PASSED THROUGH THE FORECAST AREA THIS MORNING WILL
BEGIN TO RETURN NORTHWARDS AS WINDS TURN TO OUT OF THE SOUTH. THIS
WILL MAINLY AFFECT THE ELEVATED FRONT BETWEEN 850 TO 700 MB AS THE
WARM AIR ADVECTION (WAA) ASSOCIATED WITH THIS SOUTHERLY FLOW LOOKS
TO DEVELOP ELEVATED CONVECTION ALONG THIS BOUNDARY. MEAN FLOW WILL
BE PARALLEL TO THE BOUNDARY, RESULTING IN ANY STORMS THAT FORM TO
TRAVEL DOWN THIS BOUNDARY. INSTABILITY LOOKS TO BE ON THE WEAKER
SIDE WITH CAPE VALUES ONLY UP TO AROUND 500 TO 700 J/KG. EFFECTIVE
SHEAR VALUES ARE ALSO WEAK ON THE ORDER OF 30 KNOTS OR LESS. THUS,
THESE STORMS ARE NOT EXPECTED TO BE STRONG TO SEVERE, BUT DRIER AIR
IN THE LOW LEVELS COULD RESULT IN A FEW BRIEF WIND GUSTS AND PERHAPS
SMALL HAIL. THE STORMS LOOK TO DEVELOP ACROSS CENTRAL SOUTH DAKOTA
TONIGHT BEFORE SLIDING SOUTHEASTWARDS ALONG THE BOUNDARY INTO THE
FORECAST AREA. INSTABILITY VALUES WILL BE WANING AS THEY ENTER THE
FORECAST AREA, SO THEY ARE EXPECTED TO BE WEAKENING WITH
SOUTHEASTWARD EXTENT.
SUNDAY WILL BE THE WARMEST DAY THIS WEEKEND AS THE THERMAL RIDGE
CONTINUES TO PUSH EASTWARDS. HIGH TEMPERATURES LOOK TO WARM TO THE
MID 80S TO ABOUT 100F WITH THE WARMEST TEMPERATURES OCCURRING ALONG
AND WEST OF THE JAMES RIVER VALLEY. WITH A RETURN TO SOUTHERLY FLOW
IN PLACE, SLIGHTLY HIGHER DEW POINTS WILL BE ADVECTED INTO THE AREA.
DEW POINTS LOOK TO MOISTEN TO THE 60S TO POTENTIALLY REACHING 70F IN
A FEW LOCATIONS. THIS WILL PUSH HEAT INDICES UP TO THE 90S TO LOW
100S ACROSS THE BULK OF THE AREA. THE HIGHEST HEAT INDICES WILL
OCCUR WITH THE HOTTEST TEMPERATURES ALONG AND WEST OF THE JAMES
RIVER VALLEY. AS SUCH, A HEAT ADVISORY HAS BEEN ISSUED FOR THIS AREA
FROM 1PM TO 9PM. ASIDE FROM THE HEAT, A FEW SHOWERS COULD PERSIST
INTO THE MORNING HOURS BEFORE DISSIPATING BY THE AFTERNOON
TIMEFRAME. OTHERWISE, THE REST OF THE AFTERNOON HOURS LOOK DRY.
LIGHT CONCENTRATIONS OF SMOKE LOOK TO PERSIST ACROSS THE AREA
DESPITE THE SOUTHERLY FLOW. THE DRY CONDITIONS WILL NOT LAST LONG
THOUGH AS ANOTHER CHANCE FOR SHOWERS AND STORMS LOOK TO MAKE A
RETURN TO THE AREA SUNDAY NIGHT. A SHORTWAVE TROUGH WILL PUSH OUT OF
NORTH DAKOTA AND DIVE SOUTHEASTWARDS. THIS LOOKS TO BEING SHOWER AND
STORM CHANCES TO MAINLY SOUTHWEST MINNESOTA AT THIS TIME. THE
PREVIOUSLY MENTIONED BOUNDARY WILL CONTINUE TO RETURN NORTHWARDS,
SERVING AS THE FOCAL POINT FOR THIS NEW ROUND OF CONVECTION TO
DEVELOP ON. CURRENTLY, IT SEEMS LIKE THE STORMS WILL DEVELOP ALONG
THE 925MB FRONT AND TRACK DOWN IT THROUGH THE NIGHT. VERTICAL SHEAR
WILL BE STRONGER BUT INSTABILITY VALUES LOOK TO REMAIN ON THE WEAK
SIDE OF THINGS WITH A MAGNITUDE BETWEEN 500 TO 1000 J/KG. THUS,
ISOLATED SEVERE STORMS ARE POSSIBLE ACROSS MAINLY SOUTHWEST
MINNESOTA SUNDAY NIGHT WITH LARGE HAIL AND DAMAGING WINDS AS THE
PRIMARY HAZARDS.
THE CORE OF THE THERMAL RIDGE WILL FINALLY MAKE ITS WAY OVER THE
FORECAST AREA ON MONDAY. THIS WILL PUSH HIGH TEMPERATURES ALL THE
WAY UP TO THE MID 90S TO LOW 100S. WITH SUFFICIENT MOISTURE
REMAINING IN THE AREA, HEAT INDICES WILL REACH UP TO THE 90S TO LOW
TO POTENTIALLY REACHING UP TO ABOUT 104 TO 105F. THE HOTTEST
TEMPERATURES AND HEAT INDICES WILL OCCUR ALONG AND SOUTH OF I-90.
SOME UNCERTAINTY REMAINS REGARDING THESE HOT TEMPERATURES AS A
SECOND ROUND OF THUNDERSTORMS IS POSSIBLE MONDAY AFTERNOON. A COLD
FRONT WILL BE PUSHING THROUGH THE AREA AFTER THE FIRST ROUND OF
SHOWERS AND STORMS PASSES THROUGH THE AREA MONDAY MORNING. THIS
FRONT LOOKS TO RESULT IN A SECOND ROUND OF SHOWERS AND STORMS MONDAY
AFTERNOON. AS OF NOW, IT LOOKS LIKE STORMS COULD DEVELOP EAST OF I-
29 AT THIS TIME. IF THEY DO FORM, THEY WILL AGAIN HAVE THE POTENTIAL
TO BE STRONG TO SEVERE. THERE IS UNCERTAINTY REGARDING WHERE STORMS
DEVELOP AS WELL AS IF THESE STORMS MAY AFFECT AFTERNOON HIGHS ENOUGH
TO LIMIT DIURNAL HEATING POTENTIAL. HEAT HEADLINES MAY BE NEEDED BUT
THAT DECISION WILL BE MADE ONCE CONFIDENCE INCREASES IN STORM
COVERAGE, LOCATION, AND TEMPERATURES.
MUCH DRIER AIR IS IN STORE BEHIND THE PREVIOUSLY MENTIONED COLD
FRONT. HIGH TEMPERATURES WILL RETURN TO NEAR SEASONABLE FOR THE REST
OF THE WORK WEEK WITH HIGHS IN THE 80S. A FEW CHANCES (15-35%) FOR
RAIN ARE POSSIBLE THROUGHOUT THE WEEK BUT DETAILS ARE UNCERTAIN AT
THIS TIME. TEMPERATURES MAY TREND BACK TO ABOVE AVERAGE BY NEXT
WEEKEND AS ZONAL FLOW RETURNS ALOFT.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1256 AM CDT SUN JUL 19 2026
WIDELY SCATTERED LIGHT SHOWERS AND VERY ISOLATED THUNDERSTORMS
WILL MOVE THROUGH AREAS MAINLY NEAR AND WEST OF THE JAMES RIVER
SUNDAY MORNING. ADDED A PROB30 GROUP FOR -SHRA TO ACCOUNT FOR THIS
AT KHON, BUT IT DOES LOOK LIKE THE BETTER THUNDER POTENTIAL WILL AT
LEAST BE SOUTH OF THE SITE. THIS ACTIVITY PUSHES EAST AND FADES
THROUGH THE EARLY AFTERNOON, BUT IS UNLIKELY TO CAUSE MUCH IF
ANY IMPACTS TO KFSD OR KSUX. ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS WILL MOVE IN SUNDAY NIGHT, BUT NOT ENOUGH
CONFIDENCE TO INCLUDE MENTION OF THIS IN THE TAF SITES AT THIS
TIME AS THE BETTER CHANCES CURRENTLY RESIDE OVER SOUTHWEST
MINNESOTA.
WINDS WILL TURN MORE SOUTH-SOUTHEASTERLY HEADING INTO THE DAY ON
SUNDAY, REMAINING FAIRLY LIGHT THROUGH THE PERIOD WITH THE HIGHEST
GUSTS UP TO ONLY 20 KTS NEAR AND WEST OF THE JAMES RIVER DURING THE
LATE MORNING THROUGH MIDDLE AFTERNOON. ANY STRONGER STORMS THAT MOVE
THROUGH SUNDAY NIGHT MAY BE CAPABLE OF ISOLATED WIND GUSTS TO 50 KTS
OR SLIGHTLY STRONGER.
FSD WATCHES/WARNINGS/ADVISORIES
SD...HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM CDT THIS
EVENING FOR SDZ038-050-052-053-057>060-063>065-068-069.
MN...NONE.
IA...NONE.
NE...NONE.
UPDATE...SAMET
DISCUSSION...MEYERS
AVIATION...SAMET
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