259
FXUS63 KUNR 160512
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1112 PM MDT WED APR 15 2026
KEY MESSAGES
- ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS EXPECTED FOR
THURSDAY.
- COLD FRONT MOVES THROUGH LATER THURSDAY, BRINGING RAIN/SNOW
BEHIND IT.
- WARMING TREND OVER THE WEEKEND WITH MOSTLY DRY CONDITIONS
SATURDAY THROUGH MIDDLE OF NEXT WEEK.
UPDATE
ISSUED AT 942 PM MDT WED APR 15 2026
UPPER LEVEL ANALYSIS SHOWS 500HPA WAVE/TROF EAST OF THE DAKOTAS WITH
ABUNDANT CONVECTION FIRING FROM OK NORTHEAST THROUGH OK/AR,IL
INTO WI AND MI. UPPER FLOW HAS TURNED SW OVER THE REGION AS NEXT
CLOSED 500HPA LOW/LONG-WAVE TROF DROPS INTO PAC NW. NOTED EARLIER
IN THE EVENING A FEW LIGHTNING STRIKES IN ID AS LEAD WAVE EJECTS
OUT AHEAD OF THIS SYSTEM. AT THE SURFACE, WEAK SURFACE LOW
PRESSURE IS LOCATED ACROSS WESTERN SD AS NOTED IN SURFACE WIND
FIELD AND EARLIER RETURNS ON THE KUDX RADAR. TEMPS AT 03Z ARE
STILL FAIRLY MILD, GENERALLY IN THE MID 50S TO LOWER 60S WITH
WINDS 15 MPH OR LESS. MID TO HIGH LEVEL CLOUDINESS IS STREAMING
OVER THE AREA IN THE SW FLOW ALOFT. OVERNIGHT LOWS IN THE MID 40S
TO AROUND 50 STILL LOOK TO BE ON TRACK.
CRITICAL TO NEAR CRITICAL FIRE WEATHER CONDITIONS STILL LOOK TO BE
IN STORE FOR THURSDAY ACROSS OUR SOUTHERN AND SOUTH CENTRAL ZONES,
AS GUSTY SOUTHWEST TO WEST WINDS SET UP ALONG WITH ABOVE SEASONAL
TEMPS AND LOW RELATIVE HUMIDITY. THERE IS SOME QUESTION NOW ABOUT
THE COLD FRONTAL TIMING, AS IT APPEARS TO BE SLOWING DOWN EVER SO
SLIGHTLY WHEN COMPARED TO EARLIER RUNS, BUT BY ONLY 3 OR SO HOURS
AT MOST. THIS MAY BE AN ISSUE WITH ONSET OF PCPN PROBABILITIES AS
WELL AS REACH OF FIRE WEATHER CONDITIONS. RELATIVE HUMIDITIES
STILL FALL INTO THE MID TEENS DURING THE AFTERNOON HOURS ACROSS
THE RED FLAG WARNING AREA, SO RIGHT NOW SEE NO REASON TO ALTER. AS
THE COLD FRONT COMES THROUGH, WIDESPREAD PCPN STILL LOOKS
FAVORABLE WITH MANY PLACES SEEING AT LEAST 0.05”, AND POSSIBLY UP
TO 0.35” OR HIGHER QPF. DETERMINISTIC MODELS ARE CONTINUE TO SHOW
A FAVORED SNOW BELT FROM NORTHEAST WY, NORTHERN BLACK HILLS AND
INTO NORTHWEST SD. AS PREVIOUS FCST STATED, SNOW AMOUNTS ARE
TRICKY AFTER WARM PERIOD, HOW MUCH STICKS TO GROUND AND HOW LONG
IT ACTUALLY SNOWS. WILL CONTINUE TO FOREGO ANY WINTER WX HEADLINES
ATTM.
MAIN AREA OF PCPN WILL MOVE OUT DURING THE DAY ON FRIDAY, HOWEVER
TEMPS WILL REMAIN CHILLY IN THE FRIDAY AND SATURDAY TIME FRAME.
SUNDAY WILL SEE SOME WARMER WEATHER RETURN AHEAD OF A MORE
UNSETTLED PATTERN RETURNING FOR NEXT WEEK.
DISCUSSION
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 1230 PM MDT WED APR 15 2026
CURRENT SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER SOUTHEASTERN SD,
WITH A WEAK SURFACE TROUGH STRETCHING FROM NORTHWEST SD DOWN INTO
EASTERN WYOMING. UPPER AIR ANALYSIS DEPICTS SHORTWAVE OVER NE/KS
REGION, UPPER LOW OVER THE PAC NW, WITH NEAR WEST/EAST FLOW OVER
THE FORECAST AREA. TEMPERATURES CURRENTLY SIT IN THE 60S TO LOW
70S, WITH LIGHT WINDS. RECENT SATELLITE IMAGES SHOW MID/HIGH
CLOUDS EXPANDING INTO THE FORECAST AREA FROM THE WEST.
ELEVATED TO NEAR-CRITICAL FIRE WEATHER PARAMETERS CONTINUE THIS
AFTERNOON, AS WARM AND DRY CONDITIONS PERSIST. THURSDAY WILL SEE
SOME AREAS REACH CRITICAL FIRE WEATHER CONDITIONS AHEAD OF A COLD
FRONT, AS TEMPERATURES REACH INTO THE 70S AND LOW 80S, WITH WINDS
15 TO 25 MPH, AND GUSTS UP TO 40 MPH IN THE LATE MORNING AND
AFTERNOON. COLD FRONT MOVES THROUGH FROM NORTHWEST TO SOUTHEAST
THURSDAY AFTERNOON INTO THE EVENING, BRINGING GUSTY NORTHWEST
WINDS AND CHANCES FOR RAIN/SNOW THROUGH MID-DAY FRIDAY. ANY
ACCUMULATING SNOW AMOUNTS WILL BE TRICKY GIVEN THE TIME OF YEAR,
AND TEMPERATURES HANGING NEAR FREEZING FOR SOME AREAS. HIGHEST
POTENTIAL FOR ACCUMULATING SNOWFALL IS EXPECTED IN PARTS OF
NORTHEASTERN WYOMING INTO THE CENTRAL AND NORTHERN BLACK HILLS,
WHERE NBM PROBABILITY OF 2" OR MORE RANGES BETWEEN 30 TO 70
PERCENT. WIDESPREAD LIGHT QPF IS EXPECTED, WITH THE HIGHEST
RANGES (0.05" - 0.4") STRETCHING FROM NORTHEASTERN WY INTO
NORTHWESTERN SD. CURRENT MODEL RUNS SHOW A SMALL POTENTIAL FOR LOW
END WINTER WEATHER ADVISORY HEADLINE FOR SOME AREAS THURSDAY
NIGHT, BUT AGAIN CHANCES ARE SMALL. MAIN PRECIPITATION EVENT MOVES
OUT MID-DAY FRIDAY, BUT SOME LIGHT PRECIPITATION COULD LINGER FOR
SOME AREAS (GENERALLY BLACK HILLS INTO SOUTHWEST SD) INTO
SATURDAY.
AFTER THIS SYSTEM MOVES THROUGH, MOSTLY DRY CONDITIONS RETURN LATE
SATURDAY THROUGH MIDDLE OF NEXT WEEK. UPPER RIDGE BUILDS OVER THE
WESTERN CONUS THROUGH THE WEEKEND AS WELL, RESULTING IN A WARMING
TREND BACK TO 10-20F ABOVE NORMAL. LONGER RANGE MODELS POINT TO
THE POTENTIAL FOR MORE ACTIVE WEATHER THE LATTER HALF OF NEXT
WEEK, BUT WILL HAVE TO WAIT AND SEE HOW MODEL AGREEMENT WORKS OUT.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1103 PM MDT WED APR 15 2026
VFR CONDITIONS WILL CONTINUE THROUGH THE EARLY MORNING. THE COLD
FRONT IS FORECASTED TO ARRIVE SLIGHTLY LATER THAN PRIOR, NOW
EXPECTED AT KGCC AROUND 18Z AND KRAP AROUND 23Z. SMALL CHANCES FOR
RAIN SHOWERS WILL FOLLOW THE FRONT AT BOTH SITES. HOWEVER, KGCC
CONDITIONS WILL DEGRADE TOWARD MFVR AS RAIN TRANSITIONS TO SNOW
AROUND 17/00Z.
FIRE WEATHER
ISSUED AT 1230 PM MDT WED APR 15 2026
ELEVATED FIRE WEATHER CONDITIONS CONTINUE THIS AFTERNOON ACROSS
MUCH OF THE AREA AS RH FALLS INTO THE TEENS TO LOW 20S. BEST
OVERLAP OF LOW RH AND STRONGER WINDS FORECAST ACROSS SOUTHERN
CAMPBELL AND WESTON COUNTIES IN WY THROUGH SOUTHWESTERN SD.
CONDITIONS REMAIN BELOW THRESHOLDS FOR ANY FIRE WEATHER
HIGHLIGHTS TODAY.
A RED FLAG WARNING HAS BEEN ISSUED FOR THURSDAY FOR THE WESTON
COUNTY PLAINS THROUGH SOUTHERN SD AS STRONGER SOUTHWEST WINDS WILL
DEVELOP AHEAD OF A COLD FRONT. DAYTIME MINIMUM RH WILL FALL AS
LOW AS 12-14 PERCENT THURSDAY. TIMING OF THE COLD FRONT AS WELL AS
MID-LEVEL CLOUDS AHEAD OF THE FRONT AND SPOTTY HIGH- BASED
SHOWERS MAY COMPLICATE THINGS A BIT BY KEEPING TEMPERATURES A BIT
COOLER AND RH HIGHER. HOWEVER, PLAN FOR AT LEAST ELEVATED TO
NEAR- CRITICAL CONDITIONS THURSDAY.
UNR WATCHES/WARNINGS/ADVISORIES
SD...RED FLAG WARNING FROM NOON MDT /1 PM CDT/ TO 7 PM MDT /8 PM CDT/
THURSDAY FOR SDZ321-322-325-326-332>335.
WY...RED FLAG WARNING FROM NOON TO 7 PM MDT THURSDAY FOR WYZ317.
UPDATE...HINTZ
DISCUSSION/KEY MESSAGES...DYE
AVIATION...SCHWEIGERT
FIRE WEATHER...DYE
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