673
FXUS63 KUNR 051737
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1137 AM MDT TUE AUG 5 2025
KEY MESSAGES
-SEASONALLY WARM WITH ISOLATED TO SCATTERED THUNDERSTORMS THROUGH
TOMORROW
-HOT AND DRY THURSDAY WITH WIDESPREAD 90S AND LOW 100S
-COOLER FOR THE END OF THE WEEK INTO THE WEEKEND
DISCUSSION
(TODAY THROUGH MONDAY)
ISSUED AT 123 AM MDT TUE AUG 5 2025
UPPER RIDGE WILL CONTINUE TO BUILD INTO THE REGION THROUGH
THURSDAY. THE FA WILL REMAIN ON THE NORTHERN EDGE OF THE RIDGE THE
NEXT COUPLE DAYS, OFFERING CHANCES FOR THUNDERSTORMS AS IMPULSE
ADVECT ALONG THE NORTHERN PERIPHERY OF THE RIDGE. LLJ IS
SUPPORTING ISOLATED TO SCATTERED THUNDERSTORMS OVER SOUTHWEST INTO
WEST CENTRAL SD THIS MORNING. ANOTHER AREA OF MORE ORGANIZED
STORMS IS IN SE MT, ASSOCIATED WITH A SHORTWAVE TROUGH. THIS
ACTIVITY WILL SHIFT SLOWLY EAST THROUGH MORNING AS THE WAVE MOVES
EAST. EVOLUTION OF THIS CONVECTION AND ITS MODIFICATION OF THE
LOCAL ATMOSPHERE, INCLUDING ANY OUTFLOW BOUNDARIES AND BACKSIDE
SUBSIDENCE WILL BE KEY TO HOW THINGS DEVELOP THIS AFTERNOON AND
EVENING. HIRES MODELS OFFER A PLETHORA OF SOLUTIONS WRT TO
CONVECTIVE INITIATION (CI) AND ANY RESULTANT UPSTREAM GROWTH,
MAKING TODAY'S FORECAST FAIRLY DIFFICULT. THE BEST CHANCE FOR
STORMS TODAY WILL CERTAINLY BE ACROSS NORTHWEST SD THIS MORNING
WITH THE MAIN WAVE PROGRESSING ACROSS THE REGION. NEW CONVECTION
IS EXPECTED TO DEVELOP ALONG THE SFC TROUGH MOVING ACROSS THE FA
THIS AFTERNOON. OTHER CONVENTION MAY DEVELOP IN THE NORTHERN BH IF
SUBSIDENCE CAN BE OVERCOME. CI IS ALSO POSSIBLE IN NORTHEAST WY
WITH DIURNAL HEATING AND WEAK CIN. AND IF OUTFLOW FROM STORMS
ACROSS NW SD BECOME SFC ROOTED, STORMS COULD QUICKLY GROW UPSTREAM
ACROSS THE EASTERN PORTION OF THE FA. HENCE, THERE IS A LOT OF
POTENTIAL FOR STORMS. THE QUESTION IS WHETHER THEY CAN GET DEVELOP
AND WHERE, ESP WITH ALL THE SUBSIDENCE OVER THE WESTERN HALF.
HENCE, GENERALLY KEPT POPS LOW. IF STORMS DO DEVELOP AND GROW
UPSCALE, THERE WILL BE PLENTY OF CAPE AND SHEAR AROUND TO SUPPORT
SEVERE CELLS, CAPABLE OF LARGE HAIL AND DAMAGING WINDS. THINGS
WILL DRY OUT TONIGHT WITH MAINLY DRY WEATHER WED. THE EXCEPTION
MAY BE OVER THE HIGH TERRAIN OF THE BH, FAR NW SD, AND SCENTRAL
SD, THE LATER TWO OF WHICH WILL HAVE A SFC BOUNDARY IN PLACE.
CAPPING STRENGTH WILL BE THE KEY TO WHETHER STORMS DEVELOP.
THERMAL RIDGE WILL MOVE OVER THE REGION THURS, SUPPORTING THE
WARMEST DAY WITH WIDESPREAD 90S AND LOW 100S EXPECTED. RH WILL
DROP OFF SIGNIFICANTLY IN THE WESTERN THIRD AS DEEP LAYER MIXING
OCCURS. EXPECT A DRY DAY THUR WITH THE RIDGE OVER THE FA. STORMS
COULD GRAZE THE NORTHERN HALF OF THE FA THUR NIGHT WITH AN
EXPECTED IMPULSE, HOWEVER MOST ACTIVITY LOOKS TO REMAIN NORTH
ATTM. COLD FRONT WILL MOVE THROUGH FRIDAY WITH MUCH COOLER CONDS
AS WELL AS A CHANCE FOR A FEW POST FRONTAL STORMS. DRY THIS
WEEKEND WITH SEASONAL TEMPS AS DEEP MOISTURE SHIFTS SOUTH AND HIGH
PRESSURE COVERS THE REGION.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 1134 AM MDT TUE AUG 5 2025
ISOLATED TO SCATTERED THUNDERSTORMS CAN BE EXPECTED TODAY, MAINLY
ACROSS THE BLACK HILLS AND WESTERN SD. GUSTY WINDS AND LARGE HAIL
ARE POSSIBLE WITH STRONGER STORMS. MOST OF THE STORMS SHOULD EXIT
THE AREA BY 03Z, LEAVING BEHIND VFR CONDITIONS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...JC
AVIATION...SMITH
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