449
FXUS63 KUNR 151713
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1113 AM MDT SAT AUG 15 2026
KEY MESSAGES
- ACTIVE PATTERN PERSISTS THROUGH THE WEEKEND WITH DAILY CHANCES
OF SHOWERS AND THUNDERSTORMS.
- INCREASED SEVERE WEATHER POTENTIAL SUNDAY THROUGH TUESDAY,
ALTHOUGH DETAILS REMAIN UNCERTAIN.
UPDATE
ISSUED AT 1122 PM MDT FRI AUG 14 2026
GOING FORECAST IN PRETTY GOOD SHAPE. UPPER RIDGE OVER THE
SOUTHEAST CONUS WILL SLOWLY MOVE WEST AND FLATTEN INTO EARLY NEXT
WEEK. THIS PUTS THE CWA UNDER SOUTHWEST, THEN WESTERLY FLOW ALOFT.
A PLETHORA OF SHORTWAVES WILL MOVE THROUGH, EACH BRINGING
SHOWERS/TSRA AT TIMES. INCREASING BUOYANCY/SHEAR BY SUNDAY/MONDAY
(POSSIBLY TUESDAY) WILL RESULT IN INCREASING CHANCES FOR
ACTIVE/SEVERE CONVECTION. DETAILS STILL TO BE IRONED OUT.
DISCUSSION
(THIS EVENING THROUGH FRIDAY)
ISSUED AT 115 PM MDT FRI AUG 14 2026
ACTIVE SOUTHWEST UPPER LEVEL FLOW CONTINUES WITH SOUTHEASTERLY
SURFACE FLOW. SURFACE DEW POINTS RANGE FROM THE UPPER 50S IN
WYOMING AND THE BLACK HILLS TO MID 60S ACROSS WESTERN SOUTH
DAKOTA. LOW CLOUDS ERODED THROUGH THE MORNING WITH SURFACE HEATING
DRIVING TEMPERATURES INTO THE UPPER 70S AND LOW 80S. SPC
MESOANALYSIS AND THE 18Z KUNR RAOB SHOW 500-1000 J/KG MLCAPE
ACROSS THE AREA WITH EFFECTIVE BULK SHEAR AROUND 30 TO 40 KNOTS.
SCATTERED CONVECTION IS TRYING TO DEVELOP ACROSS NW SD AND NE WY,
ALTHOUGH COVERAGE MAY BE LIMITED UNTIL A SHORTWAVE ARRIVES LATER
THIS AFTERNOON AND EARLY EVENING. WIDESPREAD SEVERE WEATHER IS NOT
ANTICIPATED, HOWEVER ISOLATED STRONG TO SEVERE STORMS ARE
POSSIBLE GIVEN THE INSTABILITY AND SHEAR PARAMETER SPACE.
DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. UPPER LEVEL FLOW IS FORECAST TO BECOME
MORE ZONAL/NORTHWESTERLY EARLY NEXT WEEK INTO MID WEEK. SEVERE
POTENTIAL INCREASES SUNDAY AND MONDAY WITH AMPLE INSTABILITY AND
SHEAR AROUND 35 TO 50 KNOTS. SEVERE POTENTIAL MAY STRETCH INTO
TUESDAY, BUT TIMING OF THE WAVE AND LOCATION OF THE SURFACE FRONT
REMAIN UNCERTAIN.
LONGER RANGE GUIDANCE SHOWS A STRONG AREA OF HIGH PRESSURE BUILDING
OVER THE SW US BY END OF NEXT WEEK INTO THE WEEKEND WITH
TEMPERATURES TRENDING WARMER FOR OUR AREA.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1110 AM MDT SAT AUG 15 2026
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
TODAY/THIS EVENING. THUNDERSTORM DEVELOPMENT WILL BEGIN AROUND
15/18Z AND LAST THROUGH 16/06Z, MAINLY OVER NORTHEAST WYOMING, THE
BLACK HILLS, AND SOUTHWESTERN SOUTH DAKOTA. TRANSIENT MVFR/IFR
CONDITIONS ARE POSSIBLE AROUND ANY HEAVIER PRECIPITATION CORES.
CONDITIONS WILL IMPROVE STARTING AROUND 16/08Z, WITH MAINLY VFR
CONDITIONS EXPECTED THROUGH THE REMAINDER OF THE TAF PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
UPDATE...HELGESON
DISCUSSION...SE
AVIATION...SCHULTZ
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