761
FXUS63 KUNR 182309
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
509 PM MDT WED MAR 18 2026
KEY MESSAGES
- A MAJOR WARMING AND DRYING TREND WILL CONTINUE FOR THE REST OF
THIS WEEK, WITH HIGH TEMPERATURES REACHING THE MID-70S TO
MID-80S BY OUR WARMEST DAYS FRIDAY AND SATURDAY, AND NO
PRECIPITATION.
- ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
THROUGH SATURDAY AS WELL, WITH TODAY AND SATURDAY BEING THE MOST
FAVORABLE DAYS TO WATCH. SLIGHTLY LIGHTER WINDS MAY BE A
LIMITING FACTOR FOR MEETING CRITICAL FIRE WEATHER CRITERIA
THURSDAY AND FRIDAY.
- A COLD FRONT WILL CROSS THE REGION BY SUNDAY MORNING, TAKING 30
DEGREES OFF OUR TEMPERATURES AND INCREASING HUMIDITIES FOR A
COUPLE DAYS.
DISCUSSION
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 145 PM MDT WED MAR 18 2026
NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA WILL REMAIN IN
NORTHWEST FLOW POSITIONED IN BETWEEN STAGNANT LONGWAVE RIDGING OVER
THE WESTERN US AND LONGWAVE TROUGHING OVER THE EASTERN US. THE
WESTERN RIDGE WILL CONTINUE TO BE OUR DOMINANT SYNOPTIC WEATHER
ENFORCER RIGHT THROUGH SATURDAY, SUPPORTING A STRONG WARMING/DRYING
TREND, MOSTLY CLEAR/SUNNY SKIES, NO PRECIPITATION, AND PERIODICALLY
BREEZY CONDITIONS. AS SUCH, ELEVATED TO CRITICAL FIRE WEATHER
CONDITIONS WILL BE THE MAIN WEATHER HAZARD/IMPACT THROUGH THE REST
OF THE WEEK. FRIDAY AND SATURDAY CONTINUE TO LOOK LIKE OUR WARMEST
DAYS, WITH HIGH TEMPERATURES RANGING FROM THE MID-70S TO MID-80S
OUTSIDE HIGHER ELEVATIONS ACROSS THE BLACK HILLS. THESE TEMPERATURES
ARE 25 TO 30 DEGREES ABOVE CLIMATOLOGICAL NORMALS FOR MID-MARCH. IN
FACT...THERE IS A 60-90 PERCENT CHANCE OF TEMPERATURES EXCEEDING 80
DEGREES SATURDAY AFTERNOON ROUGHLY SOUTH OF A LINE FROM WRIGHT, TO
RAPID CITY, TO CHAMBERLAIN, AND EVEN A 30% CHANCE OF EXCEEDING 85
DEGREES CLOSER TO THE NEBRASKA BORDER! THE BREEZIEST DAYS LOOK TO BE
TODAY AND SATURDAY, ALTHOUGH NOT CURRENTLY REACHING ADVISORY
CRITERIA. FOR THOSE PLANNING OUTDOOR RECREATION, ENJOY THE TASTE OF
SUMMER!
NOTABLE CHANGES REMAIN SCHEDULED FOR LATE SATURDAY NIGHT INTO SUNDAY
MORNING AS A COLD FRONT CROSSES THE REGION BRINGING AN INCREASE IN
HUMIDITY AND CHOPPING 30 DEGREES OFF OUR TEMPERATURES, WITH HIGHS
ONLY EXPECTED TO REACH THE UPPER-40S TO MID-50S SUNDAY AFTERNOON.
500MB HEIGHT ENSEMBLE CLUSTER ANALYSIS CONTINUES TO SHOW GOOD
AGREEMENT IN THE TIMING AND AMPLITUDE OF THIS SHORTWAVE
TROUGH/FRONTAL FEATURE. IT'S POSSIBLE SOME LIGHT RAIN AND SNOW
SHOWERS WILL ACCOMPANY THE FRONT (ALONG WITH A BIT OF WIND), BUT
OTHERWISE DRY CONDITIONS ARE EXPECTED THROUGH THE WEEKEND. SOME
DETERMINISTIC MODELS SUGGEST A BIT OF A SECONDARY FRONTAL PASSAGE
MONDAY NIGHT/TUESDAY MORNING, AND WHILE THIS FEATURE LOOKS QUITE
WEAK IN MODEL WIND AND HEIGHT FIELDS ALOFT WITH LIKELY NO
PRECIPITATION, IT MAY HELP SUSTAIN THOSE COOLER TEMPERATURES AND
SLIGHTLY MOISTER HUMIDITIES FOR A COUPLE DAYS, PERHAPS OFFERING A
BRIEF REPRIEVE ON THE FIRE WEATHER SIDE OF THINGS.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 509 PM MDT WED MAR 18 2026
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 145 PM MDT WED MAR 18 2026
HIGH PRESSURE WILL CONTINUE TO SUPPORT A STRONG WARMING/DRYING
TREND, MOSTLY CLEAR/SUNNY SKIES, NO PRECIPITATION, AND PERIODICALLY
BREEZY CONDITIONS RIGHT THROUGH SATURDAY, RESULTING IN A MULTI-DAY
STRETCH OF ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS ACROSS
PORTIONS OF NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA. NO
CHANGES HAVE BEEN MADE TODAY WITH RESPECT TO THE ONGOING RED FLAG
WARNING ACROSS SOME OF OUR SOUTHWESTERN ZONES. SEVERAL SURFACE
WEATHER STATIONS HAVE GUSTED OVER 25 MPH THUS FAR MEETING WARNING
CRITERIA, WHILE RH VALUES HAVE BEEN A BIT SLOW TO DROP...RUNNING
GENERALLY 20-30 PERCENT SO FAR. CONTINUED DRYING IS EXPECTED OVER
THE NEXT COUPLE HOURS THOUGH, WITH THE WARM TEMPERATURES AND ONGOING
DROUGHT CONDITIONS CONTRIBUTING TO THE RISK AS WELL. REGIONWIDE,
CRITICALLY LOW RH VALUES ARE FORECAST TO EXPAND THURSDAY AND FRIDAY,
BUT THE FLOW ALOFT LOOKS TO BE SLIGHTLY WEAKER AND MODEL BLENDS
GENERALLY SUPPORT SLIGHTLY LOWER DIURNAL WINDS WITH LITTLE OVERLAP
BETWEEN CRITICAL VALUES OF THE TWO ELEMENTS. THUS, ADDITIONAL RED
FLAG WARNINGS ARE NOT BEING ISSUED AT THIS TIME BEYOND TODAY. THE
MOST NEAR-CRITICAL CONDITIONS THURSDAY LOOK TO RESIDE OVER SOUTHERN
CAMPBELL COUNTY, AS WELL AS ACROSS LOWER ELEVATIONS JUST NORTH OF
THE BLACK HILLS INTO BUTTE COUNTY. WE'LL CONTINUE TO MONITOR TRENDS
IN MODEL GUIDANCE TO SEE IF ADDITIONAL WARNINGS WILL BECOME
NECESSARY, ESPECIALLY IN THESE SPOTS. WINDS LOOK TO INCREASE AGAIN
ACROSS MUCH OF THE REGION THOUGH SATURDAY WITH CRITICAL RHS
EVERYWHERE EXCEPT PERHAPS THE NORTHWESTERN SOUTH DAKOTA PLAINS, SO
THIS WILL DEFINITELY BE A DAY TO WATCH. REGIONWIDE, EXPECT GRASSLAND
FIRE DANGER TO INCREASE THROUGHOUT THE WEEK AS WELL...HIGH TO VERY
HIGH FOR THURSDAY ACROSS THE ENTIRE FORECAST AREA.
A COLD FRONT IS FORECAST TO CROSS THE REGION LATE SATURDAY NIGHT OR
SUNDAY MORNING, AND WHILE NO SIGNIFICANT PRECIPITATION IS CURRENTLY
EXPECTED BEYOND A FEW RAIN/SNOW SHOWERS, IT WILL BRING AN INCREASE
IN RH VALUES AND A 30 DEGREE DROP IN OUR TEMPERATURES. SOME
DETERMINISTIC MODELS SUGGEST A BIT OF A SECONDARY FRONTAL PASSAGE
MONDAY NIGHT/TUESDAY MORNING, AND WHILE THIS FEATURE LOOKS QUITE
WEAK IN MODEL WIND AND HEIGHT FIELDS ALOFT WITH LIKELY NO
PRECIPITATION, IT MAY HELP SUSTAIN THOSE COOLER TEMPERATURES AND
SLIGHTLY MOISTER HUMIDITIES FOR A COUPLE DAYS BEFORE WE TREND
WARMER, DRIER, AND BREEZIER AGAIN.
UNR WATCHES/WARNINGS/ADVISORIES
SD...RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR SDZ321-322-325-
326.
WY...RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR WYZ314-315-317.
DISCUSSION/KEY MESSAGES...KSMITH
AVIATION...SE
FIRE WEATHER...KSMITH
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