884
FXUS63 KUNR 260831
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
231 AM MDT TUE AUG 26 2025
KEY MESSAGES
- SEASONABLY WARM THIS WEEK.
- ISOLATED SHOWERS/STORMS ARE POSSIBLE OVER THE BLACK HILLS THIS
AFTERNOON AND WEDNESDAY AFTERNOON.
- INCREASING CHANCES FOR SHOWERS AND STORMS ACROSS THE AREA FOR
THE END OF WEEK INTO THE WEEKEND (50-70% FRIDAY AND SATURDAY).
DISCUSSION
(TODAY THROUGH MONDAY)
ISSUED AT 229 AM MDT TUE AUG 26 2025
A CALM AND MOSTLY CLEAR NIGHT HAS SETTLED OVER THE
REGION AS UPPER LEVEL RIDGING BUILDS TO THE WEST AND THE NORTHERN
PLAINS SITS UNDER NORTH-NORTHWESTERLY FLOW. SOME MID TO HIGH LEVEL
CLOUD COVER SITS OVER SOUTHWESTERN SD WITH LOW STRATUS/FOG FURTHER
SOUTH OVER THE NEBRASKA PANHANDLE. LOW DEWPOINT DEPRESSIONS, MOSTLY
CLEAR SKIES, AND LIGHT WINDS ACROSS SOUTH WESTERN SD MAY LEND TO
PATCHY FOG DEVELOPMENT THIS MORNING, ESPECIALLY IN THE LOWER LYING
AREAS.
A SEASONABLY WARM AND MOSTLY DRY DAY ON TAP AS UPPER LEVEL RIDGE
AXIS SHIFTS EASTWARD OVER THE NORTHERN PLAINS. HIGHS WILL CLIMB INTO
THE 70S ACROSS THE BLACK HILLS TO 80S ACROSS THE LOWER ELEVATIONS OF
NORTHEASTERN WY AND THE WESTERN SD PLAINS. WHILE HEIGHT RISES AND
WEAK INSTABILITY WILL KEEP THINGS DRY OVER MOST OF THE AREA, MOIST
UPSLOPE FLOW AND STEEP LOW LEVEL LAPSE RATES ON THE ORDER OF 7-8
C/KM SHOULD SUPPORT MARGINAL INSTABILITY OVER THE BLACK HILLS THIS
AFTERNOON (SB CAPE OF 500-1000 J/KG). THE MARGINAL INSTABILITY AND
TERRAIN INDUCED CONVERGENCE COULD BE ENOUGH TO TRIGGER ISOLATED
SHOWERS AND STORMS OVER THE BLACK HILLS THIS AFTERNOON. OPTED TO
LEAVE MENTION OF POPS OUT OF THE FORECAST AT THIS TIME. THE REGION
WILL SIT UNDER THE INFLUENCE OF THE UPPER RIDGE THROUGH WEDNESDAY
WITH CONTINUED WARM AND MOSTLY DRY CONDITIONS. STORMS ARE POSSIBLE
OVER THE BLACK HILLS WEDNESDAY AFTERNOON AS MONSOONAL MOISTURE
BEGINS TO MAKE ITS WAY INTO THE REGION THANKS TO SOUTHWEST FLOW
ALOFT. WITH WEAK FLOW ALOFT, DEEP LAYER SHEAR NOT LOOKING
SUBSTANTIAL ENOUGH FOR ANY NOTABLE SEVERE THREAT THIS AFTERNOON OR
WEDNESDAY.
PATTERN SHIFT ARRIVES BY WEDNESDAY AFTERNOON/THURSDAY IN THE FORM OF
DEVELOPING TROF OVER THE WESTERN US WHICH WILL FLATTEN OUT THE TROF.
THIS SHOULD ALLOW MONSOONAL MOISTURE TO MAKE IT UP TO THE NORTHERN
PLAINS AS A SERIES OF SHORTWAVES BRINGS CHANCES FOR PRECIP.
SHORTWAVE TROF PROGGED TO PUSH THROUGH THE NORTHERN PLAINS FRIDAY
AFTERNOON AND EVENING, WHICH WILL BRING MORE SUBSTANTIAL CHANCES FOR
SHOWERS/STORMS. NOT EXPECTING ANY NOTABLE SEVERE RISK AT THIS TIME
WITH BOTH INSTABILITY AND SHEAR LOOKING MARGINAL.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1127 PM MDT MON AUG 25 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...WONG
AVIATION...13
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page