086
FXUS63 KUNR 271652
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1052 AM MDT MON JUL 27 2026
KEY MESSAGES
- MARGINAL TO SLIGHT (1-2 OUT OF 5) RISK OF SEVERE THUNDERSTORMS
THIS AFTERNOON AND EVENING PRIMARILY FOR DAMAGING WINDS, BUT
LARGE HAIL MAY ALSO OCCUR.
- HOT WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH DAILY
CHANCES FOR ACTIVE THUNDERSTORMS AS RIDGE-RIDERS ROTATE THROUGH
THE NORTHERN PLAINS
DISCUSSION
(THIS AFTERNOON THROUGH SUNDAY)
ISSUED AT 1048 AM MDT MON JUL 27 2026
16Z SURFACE ANALYSIS HAD A LOW OVER NORTHEASTERN WY WITH A COUPLE
OF TROUGHS; ONE SOUTH INTO CO AND ANOTHER EAST INTO EASTERN SD.
SUSTAINED EAST/SOUTHEAST FLOW OVER WESTERN SD BRINGING INCREASING
MOISTURE TO THE AREA. WATER VAPOUR LOOP HAS UPPER RIDGE CENTERED
OVER NM WITH RIDGE AXIS INTO THE NORTHERN PLAINS. SHORTWAVE
EVIDENT OVER NORTHWEST WY, READY TO OVERTOP THE RIDGE AND CROSS
THE CWA DURING PEAK INSOLATION THIS AFTERNOON/EVENING. THAT WILL
BE THE MAIN SHORT TERM CONCERN.
THIS AFTERNOON/TONIGHT, 1-2KJ/KG SBCAPE DEVELOPS ALONG THE
AFOREMENTIONED BOUNDARIES WITH SIMILAR AMOUNTS OF DCAPE. EFFECTIVE
SHEAR FORECAST TO BE 30-45KTS AS SHORTWAVE CROSSES. CAMS SHOW
CONVECTIVE INITIATION BY 20Z, FOCUSED ON THE HIGHER TERRAIN
INITIALLY AND THEN THE SURFACE BOUNDARIES AS SBCIN ERODES.
CLUSTERS OF STORMS WILL MOVE EAST, POTENTIALLY WITH CONGEALING
COLD POOLS, INCREASING THE DAMAGING WIND THREAT. CAMS SHOW A
COUPLE CLUSTERS OF ENHANCED WIND GUSTS. THUNDERSTORMS END
OVERNIGHT. TEMPERATURES WILL BE NEAR GUIDANCE, BUT BELOW HEAT
HEADLINE CRITERIA.
TUESDAY LOOKS LESS ACTIVE RIGHT NOW GIVEN SHORTWAVE RIDGING AND
LACK OF A DISTINCT SHORTWAVE MOVING THROUGH THE AREA, BUT WOULD
STILL EXPECT SOME CONVECTION TIED TO THE TERRAIN. WEDNESDAY,
ENSEMBLE GUIDANCE SHOWS ANOTHER DISTINCT WAVE MOVING ACROSS THE
AREA DURING PEAK HEATING RESULTING IN AN ELEVATED RISK OF SEVERE
WEATHER. TEMPERATURES REMAIN HOT, BUT BELOW HEAT HEADLINES
CRITERIA.
THE REST OF THE FORECAST WILL BE DOMINATED BY THE UPPER RIDGE OVER
THE CENTRAL CONUS AND HOT WEATHER. THERE WILL BE WAVES KICKING OFF A
FEW STORMS FROM TIME-TO-TIME. IF YOU BELIEVE THE LONG TERM ENSEMBLE
GUIDANCE, SOMEONE OF A COOLDOWN MAY DEVELOP NEXT WEEK, BUT
CONFIDENCE LOW.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 512 AM MDT MON JUL 27 2026
VFR CONDITIONS GENERALLY EXPECTED THROUGH THE FORECAST PERIOD.
WILDFIRE SMOKE WILL CONTINUE TO DRIFT SOUTH INTO THE REGION TODAY,
MAINLY IMPACTING NORTHWESTERN SD AND THE CENTRAL SD PLAINS,
HOWEVER SMOKE IS NOT EXPECTED TO IMPACT VISIBILITIES TOO MUCH.
MORE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS NORTHEAST WY
AROUND 22Z AND MOVE INTO WESTERN SD DURING THE LATE AFTERNOON AND
EARLY EVENING HOURS. GUSTY AND ERRATIC WINDS AND LCL MVFR
CONDITIONS WILL BE ASSOCIATED WITH ANY THUNDERSTORMS.
FIRE WEATHER
ISSUED AT 1048 AM MDT MON JUL 27 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 AT TIMES. THE JOINT PROBABILITY OF MINRH <15%
AND WINDS >25MPH LOW AT THIS POINT. 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...WONG
FIRE WEATHER...HELGESON
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