466
FXUS63 KUNR 070435
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1035 PM MDT WED AUG 6 2025
KEY MESSAGES
- HOT THURSDAY, WITH HIGH TEMPERATURES IN THE 90S AND LOW 100S.
- COOLER FOR FRIDAY AND THE WEEKEND.
- ISOLATED TO SCATTERED THUNDERSTORMS WILL CONTINUE INTO EARLY
NEXT WEEK.
DISCUSSION
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 237 PM MDT WED AUG 6 2025
THE UPPER RIDGE WILL CONTINUE TO BUILD THROUGH THURSDAY, BEFORE A
TROUGH MOVES FROM THE PACIFIC NORTHWEST INTO THE NORTHERN PLAINS BY
FRIDAY NIGHT. THE UPPER TROUGH WILL BRING A COLD FRONT THROUGH THE
FORECAST AREA THURSDAY NIGHT AND FRIDAY.
WHILE UNDER THE INFLUENCE OF THE RIDGE, IMPULSES WILL CONTINUE TO
ADVECT ALONG THE NORTHERN PERIPHERY OF THE RIDGE TONIGHT AND
THURSDAY, SUPPORTING ISOLATED THUNDERSTORM CHANCES ACROSS MOST OF
THE AREA. THERE IS THE POTENTIAL FOR ISOLATED STRONG TO SEVERE
STORMS GIVEN SUFFICIENT CAPE AND SHEAR IN PLACE.
THE THERMAL RIDGE BECOMES CENTERED OVER THE FORECAST AREA ON
THURSDAY, RESULTING IN HIGH TEMPERATURES REACHING THE 90S TO LOW
100S. WITH DEW POINT TEMPERATURES IN THE UPPER 60S TO NEAR 70S
DEGREES, A HEAT ADVISORY MAY BE NEEDED. HOWEVER, THERE IS STILL
SOME UNCERTAINTY ON HOW FAR EAST THE DRY AIR WILL MAKE IT, AS
DEW POINTS MAY ONLY BE IN THE LOW 60S. THEREFORE, HAVE DECIDED
AGAINST ANY HEADLINES AT THIS TIME AND WILL LET THE NEXT SHIFT
RE-EVALUATE BASED ON THE LATEST GUIDANCE.
THE WARM AIR IN THE LOWER LEVELS SHOULD RESULT IN A STRONG CAP
OVER MOST OF THE AREA. HOWEVER, THERE ARE SOME SIGNALS THAT DEEP
MIXING COULD OCCUR ON THE BACKSIDE OF THE THERMAL RIDGE, WHICH
COULD SUPPORT A FEW VERY HIGH BASED CELLS IN PORTIONS OF
NORTHEASTERN WYOMING INTO FAR SOUTHWESTERN SOUTH DAKOTA, WHILE
OTHER STORMS DEVELOP OVER NORTHWESTERN SOUTH DAKOTA AS THE COLD
FRONT BEGINS TO DROP SOUTHWARD INTO THE AREA. SPEAKING OF
NORTHEASTERN WYOMING AND SOUTHWESTERN SOUTH DAKOTA, FUEL
CONDITIONS HAVE BECOME CRITICAL IN SOUTHERN CAMPBELL AND WESTERN
FALL RIVER COUNTIES. THESE CRITICAL FUELS COMBINED WITH THE HOT
TEMPERATURES, GUSTY WINDS, AND LOW RELATIVE HUMIDITY HAS PROMPTED
THE ISSUANCE OF A FIRE WEATHER WATCH FOR FIRE WEATHER ZONES 315
AND 322.
THE COLD FRONT BEGINS TO PASS THROUGH THE FORECAST AREA THURSDAY
NIGHT, BEFORE MOVING THROUGH THE ENTIRE AREA ON FRIDAY. WITH THE
SUPPORT OF THE UPPER TROUGH AND THE COLD FRONT, NORTHWESTERN
SOUTH DAKOTA COULD SEE ISOLATED TO SCATTED STORMS THURSDAY NIGHT
AND FRIDAY. THE STRONGEST DYNAMICS LOOK TO BE OVER NORTH DAKOTA,
BUT WITH PLENTY OF CAPE AND SHEAR, ANY STORM THAT MAKES IT INTO
NORTHWESTERN SOUTH DAKOTA WILL BE STRONG TO SEVERE. AS THE COLD
FRONT CONTINUES TO PUSH THROUGH FRIDAY, TEMPERATURES BEHIND THE
FRONT WILL BE COOLER AND THERE WILL BE CHANCES FOR SCATTERED SHOWERS
AND STORMS.
MODELS CONTINUE TO KEEP CHANCES FOR ISOLATED STORMS IN THE
FORECAST THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH MOVES EAST
AND THE RIDGE OVER THE WESTERN CONUS BEGINS TO REBUILD. HOWEVER,
THE FORECAST AREA WILL BE IN NORTHWEST FLOW, SO OVERALL, DRIER
CONDITIONS SHOULD PREVAIL.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1024 PM MDT WED AUG 6 2025
LOW STRATUS AND PATCHY FOG MAY DEVELOP OVER SOUTH CENTRAL SD
AFTER 09-10Z, DISSIPATING AFTER 15Z. GUSTY SOUTHERLY WINDS ARE
EXPECTED ACROSS THE WESTERN SD PLAINS THURSDAY AFTERNOON AHEAD OF
AN APPROACHING FRONT. GUSTS OF UP TO 30 KT EXPECTED, MAINLY
TOWARDS SOUTH CENTRAL SD. WINDS OVER NE WY AND NW SD WILL SHIFT
FROM SOUTH TO NORTHWEST BY THURSDAY AFTERNOON AS THE FRONT BEGINS
TO MOVE ACROSS THE REGION. THERE'S ALSO A CHANCE FOR TSRA OVER FAR
NORTHEASTERN WY INTO NORTHWESTERN SD THURSDAY EVENING.
FIRE WEATHER
ISSUED AT 237 PM MDT WED AUG 6 2025
AN APPROACHING COLD FRONT ON THURSDAY WILL BRING DRY AIR AND GUSTY
WEST TO SOUTHWEST WINDS INTO THE AREA FROM THE SOUTHWEST. HIGH
TEMPERATURES WILL REACH INTO THE 90S TO LOW 100S WHILE RELATIVE
HUMIDITY FALLS BELOW 15 PERCENT OVER PORTIONS OF NORTHEASTERN
WYOMING AND FAR SOUTHWESTERN SOUTH DAKOTA. WEST TO SOUTHWEST WINDS
OF 12 TO 18 MPH AND GUSTS OF 20 TO 30 MPH WILL RESULT IN CRITICAL
TO ELEVATED FIRE WEATHER CONDITIONS FOR PORTIONS OF THE AREA.
ADDITIONALLY, THERE IS A SMALL CHANCE FOR AN ISOLATED DRY
THUNDERSTORM IN THIS AREA. THEREFORE, A FIRE WEATHER WATCH FOR
THURSDAY HAS BEEN ISSUED FOR FIRE WEATHER ZONES 315 AND 322
(SOUTHERN CAMPBELL COUNTY WY AND WESTERN FALL RIVER COUNTY
SD) WHERE FUELS HAVE BECOME CRITICAL.
UNR WATCHES/WARNINGS/ADVISORIES
SD...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
EVENING FOR SDZ322.
WY...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
EVENING FOR WYZ315.
DISCUSSION/KEY MESSAGES...SMITH
AVIATION...WONG
FIRE WEATHER...SMITH
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