892
FXUS63 KUNR 191028
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
428 AM MDT THU MAR 19 2026
KEY MESSAGES
- CRITICAL FIRE WEATHER CONDITIONS THURSDAY FOR NORTHEASTERN
WYOMING AND PORTIONS OF WESTERN SOUTH DAKOTA, INCLUDING THE
CENTRAL AND SOUTHERN BLACK HILLS. NEAR-CRITICAL TO CRITICAL FIRE
WEATHER CONDITIONS AGAIN FRIDAY AND SATURDAY.
- VERY WARM AND DRY CONDITIONS WILL CONTINUE THROUGH SATURDAY.
- A COLD FRONT WILL CROSS THE REGION BY SUNDAY MORNING, TAKING 30
DEGREES OFF OUR TEMPERATURES AND INCREASING HUMIDITIES FOR A
COUPLE DAYS.
UPDATE
ISSUED AT 141 AM MDT THU MAR 19 2026
HAVE ADDED THE WYOMING BLACK HILLS AND NORTHERN BLACK HILLS TO THE
RED FLAG WARNING. DESPITE THE RECENT SNOWFALL, LOOKING AT AREA
WEBCAMS IT APPEARS THAT MOST OF THAT SNOW HAS MELTED, ESPECIALLY
ON SOUTH AND WEST FACING SLOPES. TAKING INTO CONSIDERATION THE
ANOMALOUSLY WARM TEMPERATURES (60S-70S), DRY AIR (13 TO 18%), AND
GUSTY WESTERLY WINDS (UP TO 30 MPH) FORECASTED IN THOSE ZONES,
HAVE FELT CONFIDENT ENOUGH IN WIDESPREAD CRITICAL FIRE WEATHER
CONDITIONS TO ISSUE A RFW.
UPDATE ISSUED AT 953 PM MDT WED MAR 18 2026
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED AGAIN FOR
NORTHEASTERN WYOMING AND PORTIONS OF WESTERN SOUTH DAKOTA
THURSDAY - HAVE ISSUED A NEW RED FLAG WARNING FROM 11AM-7PM MDT.
WELL ABOVE AVERAGE TEMPERATURES (70S TO LOW 80S), VERY
DRY AIR (RELATIVE HUMIDITY IN THE TEENS TO NEAR 10 PERCENT), AND
D1-D2 DROUGHT CONDITIONS WILL RESULT IN CRITICAL FIRE WEATHER
CONDITIONS AGAIN THURSDAY. OVERNIGHT RELATIVE HUMIDITY WILL BE
POOR TO FAIR (40 TO 55 PERCENT) FOR MUCH OF THE REGION TONIGHT,
ESPECIALLY NORTHEASTERN WYOMING AND THE BLACK HILLS. THE STRONGEST
WINDS ARE FORECAST FOR SOUTHERN CAMPBELL COUNTY AND THE NORTHERN
FOOTHILLS INTO NORTHWESTERN SOUTH DAKOTA (GUSTS TO 35 MPH). WHILE
THERE IS SOME QUESTION REGARDING THE ULTIMATE STRENGTH OF THE
WINDS ACROSS SOUTHERN SOUTH DAKOTA, TRANSIENT WIND GUSTS TO 25 MPH
LOOK POSSIBLE, ESPECIALLY DURING PEAK MIXING.
ELEVATED FIRE WEATHER CONDITIONS WILL PERSIST OVERNIGHT THURSDAY
WITH WARM TEMPERATURES AND POOR OVERNIGHT HUMIDITY RECOVERY BY
FRIDAY MORNING WITH NEAR-CRITICAL TO CRITICAL CONDITIONS AGAIN
FRIDAY AFTERNOON.
SATURDAY WILL BE THE WARMEST DAY WITH SOME PLACES PUSHING INTO THE
UPPER 80S TO NEAR 90F (WESTERN/SOUTHWESTERN SD PLAINS) AHEAD OF A
COLD FRONT. WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS ARE A
CERTAINTY SATURDAY AHEAD OF THE FRONT WITH MANY LOCATIONS AROUND
15 PERCENT RH BY MID-DAY SATURDAY.
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 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 428 AM MDT THU MAR 19 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 FROM 11 AM THIS MORNING TO 7 PM MDT THIS
EVENING FOR SDZ319>327-329-332.
WY...RED FLAG WARNING FROM 11 AM THIS MORNING TO 7 PM MDT THIS
EVENING FOR WYZ314>318.
UPDATE...WONG
DISCUSSION/KEY MESSAGES...KSMITH
AVIATION...WONG
FIRE WEATHER...KSMITH
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