465
FXUS63 KUNR 130435
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1035 PM MDT SUN JUL 12 2026
KEY MESSAGES
- VERY HOT TEMPERATURES WILL CONTINUE THROUGH MUCH OF THIS WEEK,
WITH RECORD HIGH TEMPS POSSIBLE AND DANGEROUS HEAT.
- NEAR-CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE
THIS WEEK.
UPDATE
ISSUED AT 1026 PM MDT SUN JUL 12 2026
04Z SURFACE ANALYSIS HAD HIGH OVER IA WITH A TROUGH FROM EASTERN
MT INTO EASTERN UT. DECENT GRADIENT INBETWEEN SUPPORTING GUSTY
SOUTH/SOUTHEASTERLY WINDS AT TIMES, ESPECIALLY OVER NORTHEASTERN
WY/NORTHERN SLOPES OF THE BLACK HILLS. 00Z KUNR SOUNDING TELLS THE
STORY, CAPPED AND TOASTY. WATER VAPOUR LOOP HAD HIGH OVER THE
NORTHERN PLAINS WITH MONSOON MOISTURE BUBBLING UP OVER THE WESTERN
CONUS.
PREPONDERANCE OF GUIDANCE SHOWS STRONG UPPER/THERMAL RIDGE
SUSTAINING ITSELF OVER THE CWA THROUGH TUESDAY. WESTERN EDGE OF
THE RIDGE WEAKENS SLIGHTLY BY MID-WEEK AND THEN MORE SO BY THE
WEEKEND. MONSOON MOISTURE WILL EVENTUALLY WRAP INTO THE CWA BY THE
END OF THE WEEK WHICH MAY BRING SOME CONVECTION, ESPECIALLY
IN/NEAR THE HIGHER TERRAIN OF THE BLACK HILLS. NEAR-RECORD/RECORD
MAXT FORESEEN GIVEN PROBABILISTIC GUIDANCE AND FORECAST SOUNDINGS
AT LEAST THROUGH WEDNESDAY. TOOK ANOTHER LOOK AT 4 DAYS STRAIGHT
OF HEAT INDICES 100F+/HEAT INDEX GREATER THAN 105F (FOR EXTREME
HEAT WARNING) AND THE PROBABILITY IS LOW OVER FAR NORTHWEST SD
WITH LESSER CHANCES FURTHER SOUTH. SO, WILL CONTINUE WITH HEAT
ADVISORY THROUGH THURSDAY.
DISCUSSION
(THIS EVENING THROUGH SUNDAY)
ISSUED AT 228 PM MDT SUN JUL 12 2026
EXTREME UPPER RIDGE CONTINUES TO SIT ACROSS THE NORTHERN PLAINS
THROUGH THE CENTRAL ROCKIES. AT THE SURFACE...LOW PRESSURE ACROSS
WYOMING IS KEEPING WINDS AT 10KT OR LESS ACROSS MOST OF THE NE WY
PLAINS. AS EXPECTED, TEMPS ARE IN THE TRIPLE DIGITS. THE HOTTEST
TEMPS NEARBY ARE ACROSS FAR NORTHERN CAMPBELL COUNTY THROUGH
SOUTHEASTERN MT INTO BUTTE COUNTY, IN THE 105-110F RANGE.
UNOFFICIALLY, THE WARMEST TEMPERATURE IN THE CWA SO FAR IS 111F AT A
RAWS STATION IN NORTHERN CAMPBELL COUNTY. NOT MUCH CHANGE TO THE
PATTERN IS EXPECTED THROUGH THE NEXT SEVERAL DAYS, WITH HIGHS AT OR
ABOVE 100F ACROSS THE PLAINS EACH DAY THROUGH AT LEAST THURSDAY.
THEREFORE, HAVE EXTENDED THE HEAT ADVISORY THROUGH THEN.
CONTEMPLATED UPGRADING PART OF THE CWA TO A EXTREME HEAT WARNING
BASED ON LOCAL CRITERIA (100F+ APPARENT TEMP FOR FOUR DAYS OR
LONGER) BUT WILL KEEP IT SIMPLE W/ THE ADVISORY SINCE APPARENT TEMPS
BECOME MARGINAL PAST TUESDAY AS DRIER AIR MOVES IN FROM THE WEST,
DROPPING DEWPOINTS 10-15F. THIS WILL LOWER APPARENT TEMPS ACROSS THE
MAJORITY OF THE CWA TO NEAR OR BELOW WARNING THRESHOLDS. REGARDLESS,
IT'S SPLITTING HAIRS SINCE IT WILL STILL FEEL HOT. MEDIUM RANGE
MODELS SHOW SOME RELIEF COMING NEXT WEEKEND OR EARLY NEXT WEEK AS A
COLD FRONT FINALLY PUSHES THROUGH.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1026 PM MDT SUN JUL 12 2026
EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD. GUSTY
SOUTH/SOUTHEAST WINDS WILL PERSIST OVER NORTHEASTERN WY TONIGHT,
BUT THEN DIMINISH MONDAY. GUSTY SOUTH/SOUTHEAST WINDS RETURN FOR
THE WESTERN SD PLAINS MONDAY.
FIRE WEATHER
ISSUED AT 228 PM MDT SUN JUL 12 2026
STRONG HIGH PRESSURE OVER THE REGION FOR MUCH OF THE WEEK WILL
BRING VERY HOT TEMPERATURES, ALONG WITH DRY AIR AND BREEZY WINDS.
VERY LOW HUMIDITY AND BREEZY WINDS WILL CONTINUE THROUGH THIS
AFTERNOON AND EARLY EVENING, BRINGING CRITICAL FIRE WEATHER
CONDITIONS FROM THE NORTHEASTERN WYOMING TO THE FAR WESTERN SOUTH
DAKOTA PLAINS. ON MONDAY AND TUESDAY ACROSS MUCH OF THE WESTERN
SOUTH DAKOTA PLAINS, WINDS WILL AGAIN BECOME BREEZY WITH GUSTS UP
TO 35 MPH AND COMBINE WITH THE VERY LOW HUMIDITY OF 15% OR LESS TO
SUPPORT CRITICAL FIRE WEATHER CONDITIONS. IN ADDITION, POOR
HUMIDITY RECOVERIES ARE EXPECTED EACH NIGHT. A RED FLAG WARNING
HAS BEEN EXTENDED UNTIL TUESDAY EVENING. WILL CONTINUE TO MONITOR
THE POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS FOR THE SECOND
HALF OF THE WEEK.
UNR WATCHES/WARNINGS/ADVISORIES
SD...HEAT ADVISORY UNTIL 9 PM MDT /10 PM CDT/ THURSDAY FOR SDZ001-002-
012>014-025>027-030>032-041>044-046-047-049-072>078.
RED FLAG WARNING UNTIL 9 PM MDT TUESDAY FOR SDZ322>332.
WY...HEAT ADVISORY UNTIL 9 PM MDT THURSDAY FOR WYZ054>056-058>060.
UPDATE...HELGESON
DISCUSSION...13
AVIATION...HELGESON
FIRE WEATHER...13
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