919
FXUS63 KUNR 300419
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1019 PM MDT THU MAY 29 2025
KEY MESSAGES
- AN ISOLATED STORM OR TWO COULD BE POSSIBLE ACROSS NORTHEASTERN
WY AND THE BLACK HILLS FRIDAY AFTERNOON (0-15%)
- SEASONABLY WARM AND DRY CONDITIONS THIS WEEKEND WITH HIGHS IN
THE 80S SATURDAY AND SUNDAY
- STORM CHANCES RETURN MONDAY AFTERNOON (60-80%) AS A COLD FRONT
CROSSES THE REGION. THERE IS A SLIGHT RISK (15%) FOR STORMS
ACROSS THE WESTERN SD PLAINS TO BE STRONG TO SEVERE WITH HAIL
AND DAMAGING WINDS AS THE MAIN THREATS.
- UNSETTLED WEATHER CONTINUES THROUGH NEXT WEEK WITH DAILY CHANCES
FOR SHOWERS AND STORMS. (20-50%)
DISCUSSION
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 1233 PM MDT THU MAY 29 2025
CURRENT VISIBLE SATELLITE IMAGERY DEPICTS CU FIELD OVER THE
WESTERN SD PLAINS AND BLACK HILLS. WV IMAGERY DEPICTS UPPER LEVEL
LOW/POSITIVELY TILTED TROF SITUATED OVER THE UPPER MIDWEST WITH
UPPER LEVEL RIDGE BUILDING OVER THE NORTHERN ROCKIES. WEATHER
SHOULD REMAIN DRY AND WARM THROUGH THIS AFTERNOON AS THE TROF
SHIFTS FURTHER EAST AND RIDGING BEGINS TO DOMINATE THE AREA.
FOR FRIDAY: WEAK UPPER LEVEL SHORTWAVE MOVES THROUGH REGION WITH
ATTENDANT SFC TROUGH/WIND SHIFT. MOISTURE IS LOOKING MEAGER AND
ANY FORCING IS PRACTICALLY NON-EXISTENT ... BUT THERE COULD BE
ENOUGH MID-LEVEL MOISTURE TO TRIGGER OROGRAPHICALLY FORCED
CONVECTION ALONG THE BIG HORNS IN THE AFTERNOON. CAMS AREN'T
SHOWING THESE STORMS MAKING IT FAR OFF THE BIG HORNS BUT THERE'S
THE POTENTIAL FOR ONE OR TWO STORMS TO MAKE IT INTO NORTHEASTERN
WY AND THE BLACK HILLS. RIGHT NOW, TOO LOW CONFIDENCE TO PAINT
POPS IN THOSE AREAS.
OVER THE WEEKEND: UPPER RIDGE BUILDS INTO THE REGION FOR THIS
WEEKEND WITH SEASONABLE TEMPERATURES AND MOSTLY SUNNY CONDITIONS
BEING THE SENSIBLE WEATHER IMPACTS. AFTERNOON TEMPERATURES ON
SATURDAY WILL CLIMB INTO THE 80S WITH EVEN WARMER CONDITIONS
SUNDAY (HIGHS WILL BE IN THE UPPER 80S WITH A FEW SPOTS MAKING IT
INTO THE LOW 90S). NORTHERLY FLOW COULD ADVECT WILDFIRE SMOKE
INTO THE REGION, THOUGH AT THIS TIME, NOT ANTICIPATING MUCH SMOKE
TO MAKE IT TO THE SFC.
MONDAY: CLOUDS INCREASE SUNDAY NIGHT AS THE NEXT SYSTEM
APPROACHES THE REGION. 500 MB JET MAX WILL GRAZE THE REGION WITH
SFC COLD FRONT CROSSING THE CWA MONDAY. STRONG SOUTHERLY FLOW,
DIURNAL HEATING, AND THETA-E ADVECTION COULD SUPPORT MODERATELY
UNSTABLE AIRMASS (1000- 2000 J/KG SFC CAPE PER GFS). HOWEVER,
CURRENT DETERMINISTIC RUNS DEPICT STRONGER UPPER LEVEL FLOW
DISPLACED FROM THE AXIS OF BEST INSTABILITY, SO SHEAR ISN'T
LOOKING TO BE SUPPORTIVE OF ROTATING UPDRAFTS. WITH THE UNSTABLE
AIRMASS AND LIFT FROM THE FRONT THOUGH, COULD SEE STORMS
DEVELOPING MONDAY AFTERNOON ACROSS THE WESTERN SD PLAINS TOWARDS
CENTRAL SD. A FEW STORMS MAY BECOME STRONG TO SEVERE WITH WIND
AND HAIL THE PRIMARY THREATS. MUCH OF THE AREA WILL RECEIVE
MEASURABLE RAINFALL WITH LREF PROBS DEPICTING 70-90+% CHANCES FOR
QPF MONDAY-TUESDAY EXCEEDING 0.1" ACROSS BASICALLY THE WHOLE OF
THE CWA. THE BLACK HILLS COULD POTENTIALLY SEE UP TO 0.5"
(60-70%). SOME AREAS COULD SEE LOCALLY HIGHER RAIN AMOUNTS
DEPENDENT ON WHERE THE HEAVIER SHOWERS AND THUNDERSTORMS TRACK.
TEMPERATURES SHOULD COOL SLIGHTLY AS THE COLD FRONT PASSES
THROUGH.
LATER THIS WEEK: DETERMINISTIC MODELS BEGIN TO DIVERGE BY
TUESDAY. CLUSTER ANALYSIS DEPICTS A MORE ZONAL, SEMI-PROGRESSIVE
PATTERN SETTING UP OVER THE US WITH NEAR DAILY DISTURBANCES
RIPPLING ALONG THE FLOW.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1019 PM MDT THU MAY 29 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...WONG
AVIATION...DYE
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