538
FXUS63 KUNR 100430
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1030 PM MDT TUE JUN 9 2026
KEY MESSAGES
- MILD AND BREEZY ON WEDNESDAY WITH ISOLATED SHOWERS AND
THUNDERSTORMS POSSIBLE.
- CRITICAL FIRE WEATHER CONDITIONS WEDNESDAY OVER PARTS OF
NORTHEASTERN WY AND SOUTHWESTERN SD. NEAR CRITICAL CONDITIONS
AGAIN ON FRIDAY.
- UNSETTLED WEATHER THROUGH THE WEEKEND PER A SERIES OF FRONTS
WITH UP/DOWN TEMPERATURES TRENDING COOLISH FOR THE WEEKEND.
UPDATE
ISSUED AT 1029 PM MDT TUE JUN 9 2026
KUDX/KLNX RADAR SHOWS THE LINE OF THUNDERSTORMS HAVE PUSHED EAST OF
THE CWA BORDER. HAVE CANCELLED THE TORNADO WATCH. SURFACE OBS SHOW
THE COLD FRONT HAS CROSSED NW SD AND PORTIONS OF NE WY...AND IS NOW
CROSSING STURGIS TO BISON TO LEMMON. GUSTS BEHIND THE FRONT HAVE
BEEN IN THE 30S/40S MPH RANGE. WITH THE TROUGH DRIFTING ALONG THE
MT/CANADIAN BORDER, MORE WEAK SHORTWAVES WILL ROUND THE BASE AND
CROSS THE CWA OVERNIGHT INTO WEDNESDAY. COULD SEE SOME ELEVATED
SHOWERS/ISO STORMS DEVELOP OVERNIGHT INTO THE WED MORNING HOURS.
HIGHS TOMORROW WILL BE MUCH COOLER...IN THE 70S/LOWER 80S. COOL AIR
ALOFT AND AN APPROACHING JET STREAK WILL SUPPORT SOME SHOWER
DEVELOPMENT WEDNESDAY, BUT COULD BE MOSTLY LIMITED TO NE WY/NW SD.
CRITICAL FIRE WEATHER CONCERNS WILL RETURN WEDNESDAY, BUT WILL BE
LIMITED TO SOUTHERN CAMPBELL/WESTON COUNTIES IN NE WY THROUGH FALL
RIVER/OGLALA LAKOTA COUNTIES IN SW SD. RH WILL DROP BELOW 15% WHILE
WESTERLY WINDS GUST UP TO 45 MPH. HAVE ISSUED A RED FLAG WARNING
EARLIER IN THE EVENING (SEE FIRE WEATHER DISCUSSION BELOW FOR MORE
INFO).
DISCUSSION
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 1201 PM MDT TUE JUN 9 2026
18Z SURFACE ANALYSIS HAD LOW OVER SOUTHWEST ND WITH A WAVY
STATIONARY FRONT INTO MN, A DRY-LINE INTO THE BLACK HILLS, AND A
COLD FRONT INTO SOUTHWEST WY. GUSTY SOUTHEAST WINDS AHEAD OF DRY-
LINE PER 3-5MB/3HR PRESSURE FALLS IN ND. MORNING WATER VAPOUR
LOOP/0.5KM VISIBLE IMAGERY SHOWED A DISTINCT MCV MOVING FROM
CENTRAL NE TO EASTERN SD EARLY THIS AFTERNOON. WIDENING OUR VIEW,
UPPER TROUGH OVER THE NORTHWEST CONUS WITH EMBEDDED
JETLET/SHORTWAVE OVER WY HEADING OUR WAY. EFFECTS OF THESE
FEATURES THE MAIN FORECAST CONCERN.
LATEST ENSEMBLE GUIDANCE INDICATE SHORTWAVE WILL LIFT NORTHEAST
THIS AFTERNOON WITH ATTENDANT INCREASE IN MID-LEVEL FLOW
OVERTOPPING DRYLINE. 2-3KJ/KG MEAN MUCAPE PER SPC HREF POOLS
AHEAD OF DRYLINE WITH WEAKENING MLCIN. PRELIMINARY LOOK AT 18Z
KUNR SOUNDING SHOWS THE MLCIN WELL, IN AN OTHERWISE DEEPLY MIXED-
SOUNDING WITH STEEP LAPSE RATES TO 500MB. EFFECTIVE SHEAR
FORECAST TO INCREASE TO 35-45KTS. MOST CAMS SUGGEST CONVECTIVE
INITIATION BETWEEN 09/19-21Z OVER NORTHWESTERN SD NEAREST THE DRY-
LINE/STATIONARY FRONT INTERFACE. CONVECTION SHOULD ZIPPER
SOUTH/SOUTH-EAST THROUGH THE LATE AFTERNOON/EARLY EVENING HOURS,
MOVING EAST/NORTHEAST. ANY DISCRETE STORMS HAVE THE POTENTIAL FOR
VERY LARGE HAIL AND ISOLATED TORNADOES. RIGHT NOW, MAIN MODE LOOKS
TO BE LINEAR WITH POTENTIAL FOR SIGNFICANT WIND GUSTS GIVEN 1800
DCAPE AND CAM WIND GUST OUTPUT FOR THE EASTERN HALF OF THE CWA.
BEST CONDITIONS FOR SUPERCELLS DEVELOP EAST/NORTH OF CWA THIS
EVENING. CONFIDENCE IN THUNDERSTORMS IS HIGH, BUT HOW THEY
EVOLVE/STRENGTHEN WILL BE DEPENDENT ON WHERE THE BOUNDARIES ARE
IN RELATIONSHIP TO UPPER FORCING GIVEN LOWER CONFIDENCE TO SEVERE
WEATHER EVOLUTION.
COLDER AIR FILTERS INTO THE AREA TONIGHT WITH NOTICEABLY COOLER
WEATHER FOR TUESDAY ALONG WITH SOME SHRA/TS PER CYCLONIC FLOW/VERY
WEAK BUOYANCY.
REST OF THE FORECAST LOOKS UNSETTLED AS A SERIES OF DISTURBANCES
TRAVERSE THE NORTHERN PLAINS PER NORTHWEST FLOW ALOFT. DEEPER
TROUGH BRINGS HIGHER POPS/COOLER TEMPERATURES FOR THE WEEKEND.
EACH FRONT/DISTURBANCE WILL BRING GUSTY WINDS.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1029 PM MDT TUE JUN 9 2026
VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH THE FORECAST PERIOD.
ISOLATED TO SCATTERED SHOWERS AND PERHAPS THUNDERSTORMS ARE POSSIBLE
OVERNIGHT TONIGHT INTO WEDNESDAY. MVFR/IFR CONDITIONS AND GUSTY,
ERRATIC WINDS ARE POSSIBLE WITH ANY HEAVIER STORMS. A COLD FRONT
CROSS THE AREA TONIGHT WILL BRING GUSTY NORTHWEST WINDS ACROSS MOST
LOCATIONS THROUGH WEDNESDAY.
FIRE WEATHER
ISSUED AT 918 PM MDT TUE JUN 9 2026
A COLD FRONT WILL CROSS THE AREA TONIGHT, BRINGING BREEZY
NORTHWEST WINDS THROUGH WEDNESDAY, ALONG WITH COOLER TEMPERATURES.
HOWEVER, THERE WILL BE AN AREA OF VERY DRY AIR (DOWN TO 11
PERCENT) AND GUSTY WESTERLY WINDS (GUSTS TO 45 MPH) ACROSS
PORTIONS OF THE NORTHEASTERN WYOMING PLAINS THROUGH THE
SOUTHWESTERN SOUTH DAKOTA PLAINS. THIS WILL RESULT IN CRITICAL
FIRE WEATHER CONDITIONS LATE WEDNESDAY MORNING THROUGH THE EARLY
EVENING. A RED FLAG WARNING HAS BEEN ISSUED.
THE REST OF THE WEEK WILL BE UNSETTLED AS A SERIES OF FRONTS MOVE
THROUGH, EACH CONTAINING GUSTY WINDS AND VARIABLE TEMPERATURES.
ELEVATED TO NEAR-CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
FRIDAY DUE TO VERY DRY AIR (TEENS MINIMUM RELATIVE HUMIDITY OVER
NORTHEASTERN WYOMING AND SOUTHWESTERN SOUTH DAKOTA).
UNR WATCHES/WARNINGS/ADVISORIES
SD...RED FLAG WARNING FROM 11 AM TO 8 PM MDT WEDNESDAY FOR SDZ322-326.
WY...RED FLAG WARNING FROM 11 AM TO 8 PM MDT WEDNESDAY FOR WYZ315-317.
UPDATE...13
DISCUSSION/KEY MESSAGES...HELGESON
AVIATION...13
FIRE WEATHER...13
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