992
FXUS63 KUNR 282351
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
551 PM MDT TUE JUL 28 2026
KEY MESSAGES
- ISOLATED STRONG THUNDERSTORMS THIS AFTERNOON/EVENING WITH
PRIMARY CONCERN GUSTY WINDS.
- MARGINAL TO SLIGHT (LEVEL 1-2 OUT OF 5) RISK OF SEVERE
THUNDERSTORMS LATE WEDNESDAY AFTERNOON/EVENING WITH THE PRIMARY
RISK OF DAMAGING WINDS, BUT LARGE HAIL MAY ALSO OCCUR.
- HOT WEATHER (SUNDAY LOOKS HOTTEST) WILL CONTINUE THROUGH THE
WEEKEND WITH DAILY CHANCES FOR ACTIVE THUNDERSTORMS AS RIDGE-
RIDERS ROTATE THROUGH THE NORTHERN PLAINS.
DISCUSSION
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 1224 PM MDT TUE JUL 28 2026
18Z SURFACE ANALYSIS HAD WEAK TROUGH FROM ND INTO CENTRAL WY.
WATER VAPOUR LOOP HAD UPPER RIDGE OVER CO/NM AND BUILDING HEIGHTS
OVER THE NORTHERN PLAINS - A DISTINCT WAVE HARD TO FIND. 0.5KM
VISIBLE SATELLITE LOOP HAD CU/TCU OVER CAMPBELL COUNTY, AND THEN
NEAR THE WESTERN FOOTHILLS OF THE BLACK HILLS PER DOWNSTREAM
CONVERGENCE GIVEN EAST/SOUTHEAST FLOW ON THE WESTERN SD PLAINS.
UPPER RIDGE CONTINUES TO DOMINATE THE WEATHER THIS WEEK.
THIS AFTERNOON/EVENING, 0.5-1KJ/KG MLCAPE WILL DEVELOP OVER
NORTHEASTERN WY/SOUTHWESTERN SD WITH 25-35KTS EFFECTIVE SHEAR AND
LIMITED MLCIN. ISOLATED/SCATTERED TSRA WILL DEVELOP WITH A FEW
STORMS CAPABLE OF GUSTY WINDS. CAMS NOT PARTICULARLY EXCITED ABOUT
ORGANIZED CONVECTIVE PROSPECT, PROBABLY OWING TO THE RISING MID-
LEVEL HEIGHTS. GUIDANCE TEMPERATURES LOOK FINE.
WEDNESDAY LOOKS A LITTLE MORE INTERESTING. DISTINCT SHORTWAVE
TROUGH WILL ROTATE AROUND RIDGE AND REACH EASTERN MT/WY DURING
PEAK INSOLATION, IMPINGING ON SURFACE TROUGH. 1-1.5KJ/KG MLCAPE
WILL HAVE 25-35KTS 0-6KM BULK SHEAR AVAILABLE. FORECAST SOUNDINGS
SUGGEST DAMAGING WIND WILL BE THE MAIN THREAT, ESPECIALLY OVER
NORTHWESTERN SD, BUT SOME LARGE HAIL NOT OUT OF THE QUESTION. NBM
POPS ROBUST, BUT SEEM WARRANTED GIVEN AVAILABLE SYNOPTIC SCALE
FORCING. TEMPERATURES WILL BE NEAR GUIDANCE.
THURSDAY THROUGH THE WEEKEND WILL BE VERY WARM/HOT. SUNDAY LOOKS
HOTTEST RIGHT NOW PER ROBUST THERMAL RIDGE AND PREPONDERANCE OF
ENSEMBLE GUIDANCE. PERHAPS SOME RECORD HIGHS IN JEOPARDY BY
SUNDAY. ANY DAY COULD FEATURE ACTIVE THUNDERSTORMS. THE "COOLDOWN"
FOR THE BEGINNING/MIDDLE OF NEXT WEEK STILL LOOKS LIKE IT IS
THERE, BUT THE SIGNAL KEEPS GETTING MUTED BY DIFFERING ENSEMBLE
SOLUTIONS. CONFIDENCE REMAINS LOW IN SUSTAINED HEAT RELIEF.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 551 PM MDT TUE JUL 28 2026
AN ISOLATED THUNDERSTORM WILL REMAIN POSSIBLE THIS EVENING,
ESPECIALLY OVER THE BLACK HILLS AS WELL AS THE NORTHWEST SOUTH
DAKOTA PLAINS, WITH LOCALIZED WIND GUSTS TO 45KTS AND BRIEF MVFR
CONDITIONS DIRECTLY UNDERNEATH AND ADJACENT TO STORM CORES. SO FAR
WIND HAS NOT TENDED TO PROPAGATE VERY FAR AWAY FROM STORMS.
OTHERWISE, VFR CONDITIONS ARE EXPECTED. THUNDERSTORM CHANCES
INCREASE AGAIN FOR WEDNESDAY AFTERNOON, AND BASED ON THE 12Z HREF
SUITE OF CAMS AS WELL AS MORE RECENT NAMNEST/HRRR/NBM GUIDANCE,
HAVE TIMED OUT AND INTRODUCED PROB30S FOR STORM POTENTIAL AT KGCC
AND KRAP STARTING 20-21Z/2-3PM. BRIEF MVFR CONDITIONS AND WIND
GUSTS TO 40-45KTS WILL AGAIN BE POSSIBLE, WITH A CHANCE OF AT
LEAST ISOLATED STORMS ACROSS THE ENTIRE REGION OVER THE COURSE OF
WEDNESDAY AFTERNOON AND EVENING. NORTHEAST WYOMING AND THE BLACK
HILLS WILL TEND TO BE AFFECTED FIRST, WITH BEST POTENTIAL AFTER
22Z/4PM ACROSS THE REST OF WESTERN SOUTH DAKOTA. REFINING THESE
PROB30S AND THUNDERSTORM IMPACTS WILL BE THE MAIN FOCUS IN
SUBSEQUENT UPDATES, AS NO MAJOR WIND OR CIG/VSBY ISSUES ARE
OTHERWISE EXPECTED SYNOPTICALLY.
FIRE WEATHER
ISSUED AT 1224 PM MDT TUE JUL 28 2026
ELEVATED FIRE WEATHER CONDITIONS ARE EXPECTED MUCH OF THIS WEEK
DUE TO HOT TEMPERATURES AS WELL AS MINIMUM RELATIVE HUMIDITY IN
THE TEENS AND 20S. THE JOINT PROBABILITY OF MINRH <15% AND WINDS
>25MPH IS LOW AT THIS POINT THROUGH FRIDAY. HOWEVER, AN
INCREASING SIGNAL EXISTS FOR CRITICAL FIRE WEATHER CONDITIONS FOR
SATURDAY THROUGH MONDAY IF STRONGER WINDS ARE PRESENT. THE CORES
OF THUNDERSTORMS THAT OCCUR THIS WEEK SHOULD CONTAIN WETTING RAIN,
BUT LIGHTNING STRIKES OUTSIDE OF THE CORES AS WELL AS STRONG,
ERRATIC WINDS MAY CREATE OPPORTUNITIES FOR NEW FIRES.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION...HELGESON
AVIATION...KSMITH
FIRE WEATHER...HELGESON
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