226
FXUS63 KUNR 031217
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
617 AM MDT FRI JUL 3 2026
KEY MESSAGES
- SLIGHT RISK (LEVEL 2 OF 5) OF SEVERE THUNDERSTORMS OVER WESTERN
SD TODAY WITH MAIN THREATS LARGE TO VERY LARGE HAIL (2+") AND
DAMAGING WINDS (60+ MPH).
- MARGINAL RISK (LEVEL 1 OF 5) OF SEVERE THUNDERSTORMS OVER THE
BLACK HILLS FOR SATURDAY WITH MAIN THREATS LARGE HAIL (1+") AND
DAMAGING WINDS (60+ MPH).
UPDATE
ISSUED AT 1004 PM MDT THU JUL 2 2026
STORMS ARE STILL ONGOING WITH A CLUSTER OF STRONG TO SEVERE
STORMS IN SOUTHERN MEADE COUNTY TAPPING INTO 2000 J/KG SB CAPE.
THESE STORMS HAVE A HISTORY OF PRODUCING LARGE HAIL AND WIND GUSTS
OF 60+ MPH. OUTFLOW WINDS HAVE REACHED RAPID CITY AND GUSTS OF
40+ MPH CAN BE EXPECTED OVER THE NEXT FEW HOURS AS THIS STORM
CLUSTER SLOWLY WEAKENS THROUGH MIDNIGHT.
CAMS SHOW ANOTHER ROUND OF CONVECTION MOVING INTO THE BLACK HILLS
FROM NE WY LATER TONIGHT/EARLY THIS MORNING. SOME STORMS COULD
BECOME STRONG TO SEVERE WITH MAIN HAZARDS INCLUDING LARGE HAIL
(1+") AND DAMAGING WIND GUSTS.
FORECAST REMAINS ON TRACK TOMORROW FOR MORE SEVERE WEATHER. CAMS
ARE DEPICTING STORMS DEVELOPING OVER THE BLACK HILLS BY LATER
TOMORROW AFTERNOON (AROUND 3 OR 4 PM) AND MOVING OVER THE ADJACENT
PLAINS THROUGH THE EVENING HOURS. EFFECTIVE SHEAR OF 30-40KT AND
CAPE APPROACHING 2000-3000 J/KG WILL SUPPORT SEVERE WEATHER WITH
THE PRIMARY HAZARDS BEING LARGE TO VERY LARGE HAIL (2+" IN
DIAMETER) AND DAMAGING WIND GUSTS.
DISCUSSION
(THIS AFTERNOON THROUGH WEDNESDAY)
ISSUED AT 1154 AM MDT THU JUL 2 2026
BOTTOM LINE UP FRONT: THERE WILL BE DAILY CHANCES FOR
THUNDERSTORMS, SOME STRONG TO SEVERE WITH LARGE TO VERY LARGE
HAIL AND DAMAGING WIND GUSTS AS PRIMARY HAZARDS, THROUGH MUCH OF
THE HOLIDAY WEEKEND.
UPPER LEVEL ANALYSIS DEPICTS TROUGH OVER THE WESTERN US. A SUBTLE
SHORTWAVE FEATURE IS APPARENT OVER UT/ID IN WATER VAPOR IMAGERY.
A LAYER OF WILDFIRE SMOKE ALOFT IS RESULTING IN HAZY SKIES OVER
THE NORTHERN PLAINS. CLOSER TO HOME, ISOLATED CONVECTION
ASSOCIATED WITH ANOTHER WEAK WAVE HAS DEVELOPED THIS MORNING
ACROSS NORTHEASTERN WY INTO WESTERN SD. THIS CONVECTION SHOULD
CLEAR OUT BY THE AFTERNOON, NO SEVERE WEATHER IS EXPECTED WITH
THIS ROUND OF STORMS.
THIS AFTERNOON/EVENING: ATTENTION TURNS TO THIS AFTERNOON WHERE
SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE. THERE IS
SOME QUESTION AS TO HOW THE CONVECTION THIS MORNING, THE WILDFIRE
SMOKE ALOFT, AND SUBTLE 500MB HEIGHT RISES WILL IMPACT STORM
CHANCES LATER THIS AFTERNOON AND EVENING. SHORT RANGE MODEL
GUIDANCE DEPICTS AROUND 2000-3000 J/KG CAPE OVER NORTHWESTERN INTO
SOUTH CENTRAL SD BY THIS AFTERNOON. DEEP LAYER SHEAR OF 30-40KT
WILL SUPPORT ORGANIZED CONVECTION AND MULTICELLS IN ANY STORMS
THAT DO FORM. CAMS FROM THIS MORNING SHOW STORMS DEVELOPING OFF
THE HIGHER TERRAIN OF THE NORTHERN BLACK HILLS INTO NORTHWESTERN
SD WHERE THE GREATEST INSTABILITY IS. THESE STORMS WILL HAVE THE
HIGHEST LIKELIHOOD OF BECOMING SEVERE WITH LARGE TO VERY LARGE
HAIL AND DAMAGING WIND GUSTS AS THE MAIN HAZARDS. DRY AIR NEAR THE
SURFACE WILL LIMIT OVERALL TORNADO POTENTIAL, BUT AN ISOLATED
TORNADO OR TWO CAN'T BE RULED OUT. AS FOR TIMING, DISCRETE STORMS
WILL BEGIN TO DEVELOP ALONG THE SD/MT BORDER AND THE NORTHERN
BLACK HILLS AS EARLY AS 1 PM AND MOVE EASTWARD AND GROW INTO AN
MCS THROUGH THE AFTERNOON AND EVENING. IF CONVECTION DEVELOPS FAR
ENOUGH SOUTH, THE STORMS MAY REACH THE RAPID CITY AREA BY AROUND 5
OR 6 PM.
FRIDAY: A STRONGER WAVE APPROACHES THE AREA FRIDAY WITH A RISK
FOR SCATTERED SEVERE STORMS. THE 12Z NAM HAS 2000-3000 J/KG CAPE
DEVELOPING OVER THE BLACK HILLS INTO SOUTHWESTERN AND SOUTH
CENTRAL SD BY MID AFTERNOON FRIDAY. MEANWHILE, INCREASING MID-
LEVEL FLOW WILL CONTRIBUTE TO 30-40KT EFFECTIVE SHEAR DEVELOPING
OVER THE AREA. THIS SHOULD BE ENOUGH TO SUPPORT SUPERCELL
DEVELOPMENT WITH LARGE TO VERY LARGE HAIL AND DAMAGING WINDS AS
THE MAIN THREATS. THERE'S STILL SOME UNCERTAINTY AS TO HOW THE
STORMS WILL EVOLVE WITH ANY OUTFLOWS FROM TODAY'S CONVECTION
INFLUENCING DEVELOPMENT TOMORROW.
SATURDAY: UNSETTLED FLOW CONTINUES THROUGH SATURDAY WITH
SHORTWAVE RIDGING DEVELOPING TO OUR WEST. THE RIDGE WILL LIMIT
OVERALL STORM CHANCES. HOWEVER, MODERATE INSTABILITY (2000-2500
J/KG CAPE PER THE NAM) WILL DEVELOP OVER THE BLACK HILLS BY
SATURDAY AFTERNOON WITH 30- 40KT BULK SHEAR. STORMS MAY DEVELOP
OVER THE HIGHER TERRAIN OF THE BLACK HILLS BEFORE MOVING EASTWARD
INTO THE ADJACENT PLAINS. THERE'S ENOUGH SHEAR AND INSTABILITY TO
SUPPORT MARGINAL SEVERE POTENTIAL WITH LARGE HAIL AND DAMAGING
WINDS AS THE MAIN HAZARDS.
BY SUNDAY, THE UPPER RIDGE WILL HAVE MOVED OVERHEAD AND THIS
SHOULD KEEP THINGS DRY THROUGH THE END OF THE WEEKEND. ALONG WITH
THE RIDGE, TEMPERATURES WILL WARM UP SLIGHTLY TO THE UPPER 80S TO
UPPER 90S. HOT WEATHER WITH DAILY CHANCES FOR STORMS WILL CONTINUE
THROUGH EARLY NEXT WEEK WITH HIGHS IN THE UPPER 80S TO 90S.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 617 AM MDT FRI JUL 3 2026
VFR CONDITIONS ARE GENERALLY EXPECTED ACROSS THE REGION TODAY, BUT
ANOTHER ROUND OF ISOLATED TO SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS IS EXPECTED. HAVE REFINED PROB30 GROUPS FOR KRAP AND
KGCC BASED ON THE 00Z HREF SUITE OF CAMS AND RECENT HRRR GUIDANCE.
CURRENT FORECAST CONFIDENCE IN TIMING IS MODERATE TO HIGH. STORMS
ARE EXPECTED TO INITIATE OVER NORTHEAST WYOMING AND THE BLACK
HILLS BETWEEN 19-21Z/1-3PM, WITH ISOLATED TO SCATTERED STORM
CHANCES THEN COVERING THE ENTIRE REGION AFTER 3 PM, GENERALLY
ENDING FROM WEST TO EAST BETWEEN 02-05Z/8-11PM. SOME STORMS MAY
BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS. TRANSIENT MVFR
CONDITIONS ARE POSSIBLE AROUND ANY HEAVIER PRECIPITATION CORES. WE
WILL NOTE THAT CONFIDENCE IN WINDS TODAY IS LOWER THAN USUAL
GIVEN SOME CONFLICTING AND CHANGING GUIDANCE. WINDS SHOULD START
ESE OVER THE SOUTH DAKOTA PLAINS, BUT COULD TURN NNW AT BOTH KRAP
AND KGCC THIS LATER AFTERNOON OR EVENING. OUTSIDE OF
THUNDERSTORMS, SPEEDS SHOULD GENERALLY BE 10KTS OR LESS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
UPDATE...WONG
DISCUSSION...WONG
AVIATION...KSMITH
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