494
FXUS63 KUNR 172340
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
540 PM MDT TUE MAR 17 2026
KEY MESSAGES
- A HIGH WIND WARNING REMAINS IN EFFECT UNTIL 6 PM THIS EVENING
FOR THE BLACK HILLS.
- A MAJOR WARMING AND DRYING TREND WILL TAKE HOLD FOR THE REST OF
THIS WEEK, WITH HIGH TEMPERATURES REACHING THE MID-70S TO
MID-80S BY OUR WARMEST DAYS FRIDAY AND SATURDAY.
- THE WARM AND DRY WEATHER WILL COMBINE WITH PERIODIC BREEZY
CONDITIONS TO PRODUCE MULTIPLE DAYS OF ELEVATED TO CRITICAL FIRE
WEATHER CONDITIONS THIS WEEK.
- A COLD FRONT WILL CROSS THE REGION BY SUNDAY MORNING, TAKING 30
DEGREES OFF OUR TEMPERATURES.
DISCUSSION
(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 135 PM MDT TUE MAR 17 2026
WELL...THE REST OF THIS WEEK CERTAINLY WON'T FEEL LIKE WHAT WE
EXPERIENCED THIS PAST WEEKEND! ON THE SYNOPTIC SCALE, DEEP TROUGHING
IS NOTED OVER THE EASTERN US AND LONGWAVE RIDGING IS OBSERVED OVER
THE WESTERN US, WITH NORTHEAST WYOMING/WESTERN SOUTH DAKOTA CAUGHT
IN BETWEEN UNDER NORTHWEST FLOW ALOFT. A WARM FRONT HAS LARGELY
CLEARED THE CWA, KICKING OFF A PROGRESSIVE WARMING TREND. THE CENTER
OF THE WESTERN RIDGE WILL BE ANCHORED OVER THE DESERT SOUTHWEST
THROUGH SATURDAY WITH VERY LITTLE MOVEMENT, BUT WILL BE AMPLIFIED
ENOUGH TO KEEP THE ACTIVE STORM TRACK WELL TO OUR NORTH (LARGELY
OVER CANADA) THROUGH THE PERIOD. THE RIDGE WILL THEREFORE BE OUR
DOMINANT SYNOPTIC PLAYER FROM THIS POINT FORWARD, SUPPORTING OUR
WARMING/DRYING TREND AND PERIODICALLY BREEZY CONDITIONS ALONG WITH
SOME ATTENDANT FIRE WEATHER CONCERNS.
TODAY, EXPECT HIGH TEMPERATURES TO TOP OUT IN THE MID-50S TO UPPER-
60S, A STARK CONTRAST TO THE FRIGID CONDITIONS WE BRIEFLY
EXPERIENCED OVER THE LAST COUPLE DAYS. GUSTY NORTHWEST WINDS ARE
ALSO INCREASING THIS AFTERNOON (SURFACE WEATHER STATIONS CONFIRM
SEVERAL GUSTS OF 40 TO 55 MPH SO FAR OVER THE BLACK HILLS REGION),
WITH A CONTINUED EXPECTATION THAT SOME PORTION OF 40-50KT WINDS AT
THE TOP OF THE BOUNDARY LAYER WILL MIX DOWN TO THE SURFACE. ONGOING
HIGH WIND WARNINGS ACROSS THE BLACK HILLS, AND WIND ADVISORIES
NORTH/WEST OF A LINE FROM RAPID CITY TO NEAR BRIDGER TO FAITH...AS
WELL AS OVER THE FAR SOUTHWESTERN SOUTH DAKOTA PLAINS...CONTINUE
UNTIL 6 PM BEFORE WINDS RELAX FOR THE NIGHT. IN THE WARNING AREA, 6-
HOUR PROBABILITIES OF WINDS GUSTING OVER 55 MPH REMAIN 60-80
PERCENT, ESPECIALLY FROM JUST NORTH/WEST OF CUSTER UP TO THE LEAD,
DEADWOOD, AND STURGIS AREAS. A STRAY SHOWER OR SPRINKLE CAN'T BE
RULED OUT WELL SOUTH AND WEST OF GILLETTE AND NEWCASTLE THROUGH THIS
EVENING, BUT LITTLE TO NO QPF IS EXPECTED IF THIS OCCURS. THE WARMER
TEMPERATURES STARTING TODAY WILL RAPIDLY MELT WHAT SNOWPACK REMAINS
ACROSS PORTIONS OF THE REGION FROM OUR RECENT WINTER STORM.
THE WARMING TREND CONTINUES ALL THE WAY THROUGH SATURDAY WITH HIGHS
SURGING INTO THE MID-60S TO MID-70S WEDNESDAY, 70S TO NEAR 80
THURSDAY, AND MID-70S TO LOWER 80S FRIDAY AND SATURDAY, WHICH WILL
PLACE OUR REGION 25 TO 30 DEGREES ABOVE CLIMATOLOGICAL NORMALS FOR
MID-MARCH! AT THIS TIME, THERE IS ONLY A 10-20 PERCENT CHANCE OF
EXCEEDING 80 DEGREES THURSDAY AFTERNOON FOCUSED OVER THE SOUTHWEST
SOUTH DAKOTA PLAINS, BUT THOSE PROBABILITIES INCREASE AND EXPAND
SIGNIFICANTLY FOR FRIDAY AND SATURDAY (THE TWO WARMEST DAYS). DRIER
HUMIDITY VALUES AND SOME MODEST WIND WILL ALSO RESULT IN A SEVERAL
DAY STRETCH OF NEAR-CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS
(MORE ON THAT IN THE FIRE WEATHER SECTION BELOW). NOTABLE CHANGE
ARRIVES BY SUNDAY MORNING, HOWEVER, 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 CLUSTER ANALYSIS AND EOF
PATTERNS SHOW REMARKABLY GOOD AGREEMENT IN THE TIMING AND AMPLITUDE
OF THIS SHORTWAVE TROUGH/FRONTAL FEATURE. IT'S POSSIBLE SOME RAIN
AND SNOW SHOWERS WILL ACCOMPANY THE FRONT (ALONG WITH A BIT OF
WIND), OTHERWISE DRY CONDITIONS ARE EXPECTED THROUGH THE WEEKEND.
AND, ONLY ONE MODEL CLUSTER (REPRESENTING ABOUT 30% OF THE MODEL
ENSEMBLE SPACE) IS RUNNING WETTER THAN THE MEAN, EVEN THEN STILL
COMING IN AT UNDER 0.10 INCHES QPF. THUS, SIGNIFICANT PRECIPITATION
DOES NOT SEEM LIKELY AT THIS JUNCTURE TO HELP MODERATE OUR DRY LATE-
WINTER.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 538 PM MDT TUE MAR 17 2026
GUSTY NW WINDS WILL DIMINISH BETWEEN 00-02Z THIS EVENING. VFR
CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH GRADUALLY
CLEARING SKIES OVERNIGHT INTO WEDNESDAY. NORTHWEST WINDS WILL
INCREASE AGAIN AFTER 17-18Z WEDNESDAY WITH GUSTS 25 TO 35 KNOTS.
FIRE WEATHER
ISSUED AT 135 PM MDT TUE MAR 17 2026
A LARGE RIDGE OF HIGH PRESSURE ANCHORED OVER THE DESERT SOUTHWEST
WILL BECOME OUR DOMINANT WEATHER ENFORCER FROM TODAY ONWARD THROUGH
SATURDAY, SUPPORTING A STRONG DRYING/WARMING TREND DAY-BY-DAY AS
WELL AS PERIODS OF AT LEAST MODEST/MODERATE WINDS AT TIMES. THIS
WILL RESULT IN A MULTI-DAY STRETCH OF NEAR-CRITICAL TO CRITICAL FIRE
WEATHER CONDITIONS ACROSS PORTIONS OF NORTHEAST WYOMING AND WESTERN
SOUTH DAKOTA, UNTIL A COLD FRONT ARRIVES SUNDAY MORNING BRINGING AN
INCREASE IN RH VALUES AND A 30 DEGREE DROP IN OUR TEMPERATURES.
FOR TODAY, NORTHWEST WINDS WILL BE THE PRIMARY CONCERN WITH GUSTS OF
40-50 MPH ACROSS THE NORTHWEST AND SOUTHWEST SOUTH DAKOTA PLAINS AND
GUSTS OF 50-60 MPH OVER PORTIONS OF THE BLACK HILLS (HIGH WIND
WARNINGS AND WIND ADVISORIES COVER THESE AREAS). THE STRONGEST WINDS
ARE EXPECTED THROUGH ABOUT 5-6 PM THIS EVENING. LUCKILY, MINIMUM
AFTERNOON RH VALUES WILL HOLD AT 25-35 PERCENT IN THESE AREAS.
ELSEWHERE, EVEN HIGHER RH VALUES AND RECENT SNOW COVER WILL HELP
MITIGATE FIRE RISK, BUT THE WARMER AIR TODAY (HIGHS IN THE MID-50S
TO UPPER-60S) WILL LEAD TO RAPID MELTING OF REMAINING SNOW IN MOST
AREAS, SO THIS WON'T HELP US MUCH IN DAYS AHEAD.
WEDNESDAY, CONFIDENCE HAS INCREASED IN MEETING RED FLAG CRITERIA
ACROSS THE FALL RIVER COUNTY, SOUTHERN CAMPBELL, AND WESTON COUNTY
PLAINS ZONES, AND THE PREVIOUS FIRE WEATHER WATCH HAS BEEN UPGRADED
TO A RED FLAG WARNING FROM 10 AM TO 7 PM. EXPECT WNW WINDS OF 10 TO
20 MPH WITH GUSTS UP TO 35 MPH, ALONG WITH MINIMUM AFTERNOON
RELATIVE HUMIDITY VALUES APPROACHING 15 PERCENT. ELSEWHERE, MINIMUM
RH VALUES WILL GENERALLY RANGE FROM 25-40 PERCENT WITH SLIGHTLY
LOWER WINDS (ALTHOUGH GUSTS TO 35 MPH WILL ALSO BE REALIZED ACROSS
THE NORTHWEST SOUTH DAKOTA PLAINS). WINDS MAY BE SLIGHTLY LOWER/MORE
MARGINAL THURSDAY AND FRIDAY COMPARED TO WEDNESDAY, BUT RH VALUES
WILL DROP AS LOW AS 12-16 PERCENT IN THE ABOVE MENTIONED AREAS IN
OUR SOUTHWEST CWA ALONG WITH TEMPERATURES SURGING INTO THE UPPER 70S
TO EVENTUALLY LOWER 80S, SO...QUITE WARM AND DRY. WE WILL LIKELY
EVALUATE ONE DAY AT A TIME FOR RED FLAG DECISIONS, BUT AT THE VERY
LEAST EXPECT ELEVATED TO NEAR-CRITICAL CONDITIONS TO CONTINUE
THROUGH SATURDAY UNTIL THE COLD FRONT ARRIVES. REGIONWIDE, EXPECT
GRASSLAND FIRE DANGER TO INCREASE THROUGHOUT THE WEEK AS WELL.
UNR WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR SDZ001-002-012-013-
025-027-041-073-078.
HIGH WIND WARNING UNTIL 6 PM MDT THIS EVENING FOR SDZ024-028-029-
072.
RED FLAG WARNING FROM 10 AM TO 7 PM MDT WEDNESDAY FOR SDZ322.
WY...RED FLAG WARNING FROM 10 AM TO 7 PM MDT WEDNESDAY FOR WYZ315-317.
DISCUSSION/KEY MESSAGES...KSMITH
AVIATION...SE
FIRE WEATHER...KSMITH
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