002
FXUS63 KUNR 212312
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
512 PM MDT SAT MAR 21 2026
KEY MESSAGES
- CONTINUED UNSEASONABLY WARM CONDITIONS TODAY WITH HIGH
TEMPERATURES IN THE 80S AND 90S; RECORD HIGHS POSSIBLE.
- NEAR-CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS THROUGH THIS
EVENING DUE TO LOW HUMIDITIES, GUSTY WINDS, AND THE WARM
TEMPERATURES; RED FLAG WARNING FOR MOST OF THE REGION.
- COLD FRONT CROSSES THE REGION THIS EVENING INTO TONIGHT, TAKING
ABOUT 30 DEGREES OFF OUR TEMPERATURES FOR SUNDAY AND INCREASING
HUMIDITIES; STILL NO SIGNIFICANT PRECIPITATION.
- GENERALLY MILD AND DRY WEATHER RESUMES FOR A PORTION OF NEXT
WEEK WITH ELEVATED TO NEAR-CRITICAL FIRE WEATHER CONDITIONS
QUICKLY RETURNING; COOL-DOWN POSSIBLE FOR THE END OF THE WEEK.
DISCUSSION
(THIS EVENING THROUGH SATURDAY)
ISSUED AT 145 PM MDT SAT MAR 21 2026
DOMINANT HIGH PRESSURE RIDGING OVER THE WESTERN US WILL SOMEWHAT
BREAK DOWN AND GIVE WAY TO MORE OF A ZONAL NATURE TO THE FLOW OVER
THE NEXT WEEK, PLACING NORTHWESTERN WYOMING AND WESTERN SOUTH DAKOTA
IN A SLIGHTLY MORE ACTIVE STORM TRACK...AT LEAST ENOUGH TO MORE
FREQUENTLY BREAK UP OUR STRETCHES OF HEAT AND CRITICAL FIRE WEATHER,
EVEN IF VERY LITTLE PRECIPITATION RELIEF REMAINS ON THE HORIZON. OUR
FIRST BIG CHANGE WILL BE THE LONG-ADVERTISED COLD FRONT CROSSING THE
CWA FROM NORTH TO SOUTH THIS EVENING AND TONIGHT, SWITCHING GUSTY
WINDS INTO THE NORTH AND BRINGING IN COOLER TEMPERATURES AND
SLIGHTLY HIGHER HUMIDITIES. A FEW SHOWERS REMAIN LIKELY WITH THE
FRONT (AND WE MASSAGED POPS UP SLIGHTLY AND BROADBRUSHED THEM OUT A
BIT OVER NBM GUIDANCE TO CAPTURE THE RANGE OF SOLUTIONS OFFERED BY
THE 12Z HREF CAMS), YET WE STILL DON'T EXPECT ANYONE TO EXCEED 0.10
INCHES OF QPF FROM THIS SYSTEM. WE ALSO BUMPED WINDS UP A BIT FROM
THIS AFTERNOON INTO THE FIRST HALF OF TONIGHT ON EITHER SIDE OF THE
FRONT (BLENDING THE ONGOING FORECAST WITH A HINT OF THE NBM 75TH
PERCENTILE). THE WESTERN RIDGE TRIES TO AMPLIFY JUST SLIGHTLY
THROUGH THE FIRST HALF OF THE UPCOMING WEEK BRINGING BACK SOME
WARMING AND DRYING (AND A QUICK RETURN OF ELEVATED TO NEAR-CRITICAL
FIRE WEATHER CONDITIONS), BUT ANOTHER TROUGH WILL LIKELY BRING
ANOTHER NOTICEABLE COOL-DOWN AND A FEW LIGHT SHOWERS THURSDAY, WITH
COOLER TEMPS CONTINUING INTO NEXT WEEKEND. 500MB HEIGHT ENSEMBLE
CLUSTER ANALYSIS OFFERS OUTSTANDING AGREEMENT THROUGH THURSDAY, BUT
THEN STARTS TO SHOW SOME LARGE POTENTIAL DIFFERENCES IN THE
ORIENTATION OF OUR SYNOPTIC FLOW (RIDGING? ZONAL? NORTHWEST?) BY THE
WEEKEND AS WELL AS UNCERTAINTY AROUND THE POTENTIAL AMPLIFICATION OF
TROUGHING UPSTREAM MOVING INTO THE PACIFIC NW AND NORTHERN ROCKIES.
THUS, OVERALL FORECAST CONFIDENCE IS CURRENTLY LOW FRIDAY ONWARD.
WE'RE STILL NOT, HOWEVER, SEEING SIGNS OF ANY SIGNIFICANT
PRECIPITATION-MAKERS IN OUR FUTURE.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 509 PM MDT SAT MAR 21 2026
A COLD FRONT AND ASSOCIATED UPPER LEVEL DISTURBANCE WILL MOVE
INTO THE AREA THIS EVENING. WINDS WILL SHIFT NORTHERLY WITH GUSTS
OVER 40 KNOTS POSSIBLE ON THE SD PLAINS EAST OF THE BLACK HILLS.
MVFR CIGS WILL MOVE INTO THE AREA LATER THIS EVENING WITH
SCATTERED SHOWERS POSSIBLE ACROSS PARTS OF THE AREA OVERNIGHT INTO
SUNDAY MORNING. WINDS WILL DIMINISH SUNDAY MORNING WITH CONDS
IMPROVING TO VFR BY LATE MORNING/EARLY AFTERNOON ALL PLACES.
FIRE WEATHER
ISSUED AT 145 PM MDT SAT MAR 21 2026
A COMBINATION OF VERY WARM TEMPERATURES IN THE 80S AND 90S, LOW
RELATIVE HUMIDITIES OF 8 TO 20 PERCENT, WINDS GUSTING AS HIGH AS 35-
40 MPH (DIRECTION WILL VARY DEPENDING ON LOCATION), AND ONGOING
DROUGHT WILL RESULT IN ANOTHER DAY OF WIDESPREAD CRITICAL FIRE
WEATHER CONDITIONS THROUGH THIS EVENING ACROSS MUCH OF NORTHEASTERN
WYOMING AND WESTERN SOUTH DAKOTA. A RED FLAG WARNING REMAINS IN
EFFECT FOR MOST OF THE REGION THROUGH 9 PM MDT THIS EVENING, AND WAS
EXPANDED EARLIER THIS MORNING TO INCLUDE THE BUTTE COUNTY AREA. THIS
AREA WILL BE ONE OF THE FIRST TO SEE THE COLD FRONT MOVE IN THIS
EVENING SUPPORTING PREDOMINANTLY NORTH/NORTHEAST WINDS AND
EVENTUALLY HIGHER RH VALUES, BUT MOST GUIDANCE STILL ACHIEVES AT
LEAST 15-20 PERCENT MIN RH, AND CONCEPTUALLY IT SEEMS LIKELY THAT
THERE WILL BE SOME OVERLAP OF LOW RHS WITH CRITICALLY BREEZY
CONDITIONS FOR A FEW HOURS THIS AFTERNOON/EVENING (CURRENT SFC OBS
ARE APPROACHING 20 PERCENT RH AS OF THIS WRITING IN THE WESTERN PART
OF THE ZONE). ALONG SIMILAR THINKING WITH THE COLD
FRONT...CONFIDENCE IN ACHIEVING RED FLAG CRITERIA IS HIGH FOR BOTH
WINDS AND RH ACROSS NORTHEASTERN WYOMING AND THE SOUTHWESTERN SOUTH
DAKOTA PLAINS, BUT CONFIDENCE IN RHS DROPS ALONG THE I-90 CORRIDOR
AND POINTS NORTHWARD AS CURRENT OBS CARRY SLOWER DRYING ON AN EAST
TO NORTH WIND DEPENDING ON LOCATION, WITH THE FRONT ON THE WAY. ALL-
IN-ALL...CERTAINLY NOT CONFIDENT AT ALL IN CLEARING ANY ZONE FROM
THE WARNING EARLY THIS AFTERNOON, AND WE ENCOURAGE EVERYONE TO TAKE
PRECAUTIONS TO AVOID SPARKING ANY NEW FIRES IN THIS ENVIRONMENT.
WINDS WILL ALSO BE QUITE GUSTY ALONG AND BEHIND THE FRONT THIS
EVENING INTO TONIGHT WITH A MORE DEFINITIVE SWITCH TO NORTH ACROSS
OUR ENTIRE FORECAST AREA, AND WETTING RAINS ARE NOT EXPECTED
ANYWHERE WITH SHOWER ACTIVITY ALONG THE FRONT.
LOOKING AHEAD, SUNDAY WILL STILL BE A BIT BREEZY, ESPECIALLY ACROSS
THE NORTHWESTERN SOUTH DAKOTA PLAINS, BUT AFTERNOON RH VALUES LOOK
TO HOLD MORE IN THE 20-35 PERCENT RANGE, SO SOME TEMPORARY
IMPROVEMENT THERE ALONG WITH COOLER HIGH TEMPERATURES IN THE 50S TO
NEAR 60. A DRYING/WARNING TREND RETURNS, HOWEVER, INTO MID-WEEK,
WITH ELEVATED TO NEAR-CRITICAL FIRE WEATHER CONDITIONS RETURNING TO
PORTIONS OF THE REGION EACH DAY. WINDS LOOK TO STRENGTHEN THE MOST
OUT TOWARD WEDNESDAY AND THURSDAY, WITH RELATIVELY LOW FORECAST
CONFIDENCE THEREAFTER.
UNR WATCHES/WARNINGS/ADVISORIES
SD...RED FLAG WARNING UNTIL 9 PM MDT /10 PM CDT/ THIS EVENING FOR
SDZ319>327-329-331>335.
WY...RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR WYZ314>318.
DISCUSSION/KEY MESSAGES...KSMITH
AVIATION...JC
FIRE WEATHER...KSMITH
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