059
FXUS63 KUNR 272348
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT SAT JUN 27 2026
KEY MESSAGES
- SCATTERED TO NUMEROUS SEVERE STORMS POSSIBLE THIS
AFTERNOON/EVENING, WITH THE HIGHEST RISK IN NORTHWESTERN SD.
MAIN THREATS OF VERY LARGE HAIL, STRONG WINDS, AND AN ISOLATED
TORNADO OR TWO POSSIBLE.
- ISOLATED SEVERE STORMS POSSIBLE SUNDAY.
- GRADUAL WARMING TREND THROUGH NEXT WEEK, WITH POSSIBLE 100S BY
FRIDAY.
DISCUSSION
(THIS AFTERNOON THROUGH FRIDAY)
ISSUED AT 1017 AM MDT SAT JUN 27 2026
CURRENT UPPER AIR MODELS SHOW MILD RIDGE OVER THE MIDWEST REGION
AND SHORTWAVE OVER THE MT/WY AREA, UPPER LOW OVER THE PAC NW. AT
THE SURFACE, LOW PRESSURE SITS OVER SOUTHEASTERN MT, WITH A
FRONTAL BOUNDARY STRETCHING DOWN THROUGH WY. TEMPERATURES
CURRENTLY SIT IN THE UPPER 60S AND 70S, WITH BREEZY SOUTH TO
SOUTHEASTERLY WINDS THIS MORNING.
SHORTWAVE AND ATTENDANT SFC LOW / FRONTAL BOUNDARY SLIDES ACROSS
THE REGION TODAY. NO SHORTAGE OF AVAILABLE ENERGY TODAY, WITH ML
CAPE VALUES 3000-4500 J/KG FOR AREAS EAST AND NORTH OF THE BLACK
HILLS THIS AFTERNOON, WHILE SOUTHWESTERN TO SOUTH-CENTRAL SD SIT
IN THE 1500-3000 J/KG RANGE. EFFECTIVE SHEAR RANGES FROM 30-45KTS
AS WELL THIS AFTERNOON, MAKING FOR A GOOD SUPERCELL DEVELOPMENT
DAY. STORMS TODAY WILL BE CAPABLE OF LARGE HAIL (2"+) AND STRONG
WINDS (70MPH+). TORNADO THREAT IS ALSO PRESENT TODAY, WITH THE RAP
SHOWING NORTHWEST INTO CENTRAL SD 50-100 HELICITY, LCL'S AROUND
1000-1500 METERS, AND SIG TOR OF 2-3 FOR NORTHWESTERN SD. SPC HAS
NORTHWESTERN SD IN A 10% TOR, WHICH IS SIGNIFICANT FOR OUR REGION.
CAMS SHOW STORMS POPPING IN THE 19-21Z TIMEFRAME MAINLY OVER MT
AND WY, MOVING NORTHEAST. MAIN SEVERE THREAT WILL BE OVER
NORTHWESTERN SD FOR OUR CWA, HOWEVER CAMS DO TRY TO POP A COUPLE
CELLS OVER SOUTHWESTERN SD MID-AFTERNOON. SEVERE THREAT IS A BIT
LOWER OVER THE BLACK HILLS AND RAPID CITY AREA, BUT CANNOT BE
COUNTED OUT. STORM THREAT RUNS THROUGH MIDNIGHT, BUT BY LATE
EVENING, SHOULD BE LOCATED CLOSER TO CENTRAL SD.
BY SUNDAY, UPPER LOW IS EXPECTED OVER THE ID/MT REGION, WITH A
MORE SOUTHWEST FLOW OVER THE FORECAST AREA, AND ANOTHER CHANCE FOR
STORMS MORE IN THE EVENING TO MONDAY MORNING TIMEFRAME. ISOLATED
SEVERE STORMS MAY BE POSSIBLE AGAIN, HOWEVER BIT LESS ENERGY AND
SHEAR TO SUPPORT WIDESPREAD SEVERE STORMS.
WITH THE UPPER LOW MOVING EAST OF THE ROCKIES, TEMPERATURES DIP A
BIT FOR SUNDAY AND MONDAY, THOUGH STILL IN THE UPPER 70S AND 80S.
TEMPERATURES GRADUALLY CLIMB DURING THE WEEK, AS MAIN RIDGE BUILDS
TO THE EAST OF US, AND SHORTWAVE RIDGE BUILDS OVER THE ROCKIES.
BY FRIDAY, SOME AREAS COULD SEE TEMPS CLIMB TO AROUND 100. WPC
HEAT RISK CLIMBS INTO THE MODERATE-MAJOR RANGE FOR THURSDAY AND
FRIDAY.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 536 PM MDT SAT JUN 27 2026
ONGOING STRONG TO SEVERE THUNDERSTORMS ACROSS WESTERN SD ARE
PRODUCING WIND GUSTS TO 50+ KNOTS OR GREATER. THESE STORMS ARE
MOVING TO THE NORTHEAST, SO EXPECT LOCAL MVFR CIGS/VSBYS WITH THE
STRONGER STORMS. THE ENTIRE COMPLEX OF STORMS IS EXPECTED TO MOVE
EAST OF THE AREA BY 28/06Z WITH VFR CONDITIONS THERE AFTER. LOOK
FOR WESTERLY WINDS TO INCREASE AFTER 28/15Z.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION...DYE
AVIATION...HINTZ
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