957
FXUS63 KUNR 131747
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1147 AM MDT SAT SEP 13 2025
KEY MESSAGES
- UNSETTLED WEATHER TO CONTINUE THROUGH THE REMAINDER OF THE
WEEKEND
- POTENTIAL FOR LOCALLY HEAVY RAINFALL THROUGH SUNDAY
- WARM START TO THE WORK WEEK ON MONDAY, THEN COOLING WITH MORE
PRECIPITATION CHANCES
DISCUSSION
(TODAY THROUGH FRIDAY)
ISSUED AT 220 AM MDT SAT SEP 13 2025
LATEST SATELLITE IMAGERY SHOWS 500HPA TROUGH/LOW ACROSS THE
INTER-MOUNTAIN WEST, WITH RIDGE AXIS NOSING NORTHEAST FROM CENTRAL
TX INTO THE GREAT LAKES AREA. SHORTWAVES EJECTING INTO THE
NORTHERN PLAINS ARE BRINGING WIDESPREAD SHOWERS AND THUNDERSTORMS
TO THE REGION. AT THE SURFACE, AN AREA OF LOW PRESSURE IS LOCATED
IN THE VCNTY OF KVTN WITH AN INVERTED SFC TROUGH NOSING NORTHWARD
ALONG THE MISSOURI RIVER INTO CENTRAL ND. THERE IS ANOTHER
TRAILING SFC TROUGH SOUTHWEST THROUGH THE NE PANHANDLE AND INTO
NORTHEAST COLORADO.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH LEAD EJECTING WAVE EARLY
THIS MORNING SHOULD LIFT INTO ND BY EARLY AFTERNOON, LEAVING
MOSTLY DRY CONDITIONS BEHIND. ENSEMBLES ARE SHOWING MEAN LAYER
CAPE VALUES AOA 1300 J/KG WITH 30-35KT SHEAR AROUND THE BLACK
HILLS, AND WITH SUFFICIENT MOISTURE AROUND, WILL NEED TO KEEP SOME
LOW POPS GOING THERE FOR THE AFTERNOON PERIOD. AS THINGS LIFT
NORTHWARD, THERE SHOULD BE A GENERAL DECREASING TREND IN
CLOUDINESS FROM WEST TO EAST AS WELL.
THOUGHTS THEN TURN TOWARD TONIGHT AND SUNDAY. MAIN 500HPA TROUGH
EJECTS ONTO THE PLAINS WITH STRONG SOUTHERLY FETCH OF MOISTURE
AHEAD OF IT. BY 18Z SUNDAY PWAT VALUES FROM THE BLACK HILLS AND
EASTWARD CLIMB INTO THE 175-225% OF NORMAL RANGE. ENSEMBLES ARE
SHOWING 24 RAINFALL PROBABILITIES OF 1.5” FROM 20-45% FOR MUCH OF
THE AREA EAST OF THE BLACK HILLS BY MID-AFTERNOON SUNDAY. AGAIN,
LOCALLY HEAVY RAINFALL IS EXPECTED WITH SOME OF THE STRONGER
STORMS AND IF SOUTH TO NORTH TRAINING CELLS, MIGHT HAVE TO KEEP AN
EYE OF FLASH FLOOD GUIDANCE.
700HPA THETA-E DOWNGLIDE MOVES IN BEHIND EXITING SYSTEM, HELPING
TO DRY THINGS OUT FOR THE AREA BEGINNING SUNDAY NIGHT AND
CONTINUING INTO MONDAY. TEMPS AT 850HPA WARM THROUGH THE DAY WITH
THE WY COUNTIES MOST LIKELY BEING THE WARMEST ON MONDAY. THIS WARM
UP APPEARS TO BE SHORT-LIVED AS THE NEXT 500HPA TROUGH MOVES INTO
THE REGION BRINGING AN INCREASE IN CLOUDINESS(IE...COOLER TEMPS)
AND MORE UNSETTLED WEATHER FOR THE REMAINDER OF THE WEEK.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1141 AM MDT SAT SEP 13 2025
ISOLATED TO SCATTERED THUNDERSTORMS WILL BE POSSIBLE THIS EVENING,
HOWEVER LOW CONFIDENCE ON ANY STORMS AFFECTING THE TAF SITES.
EXPECT MOSTLY VFR CONDITIONS TODAY OUTSIDE OF STORMS. INCREASING
CLOUD COVER TONIGHT INTO SUNDAY MORNING WILL BRING WIDESPREAD
MVFR/IFR CIGS OVERNIGHT FOR MUCH OF THE WESTERN SD PLAINS. TAF
FORECASTS REMAIN VFR HOWEVER ITS POSSIBLE LOW CIGS COULD GET FAR
ENOUGH WEST TO AFFECT KRAP. WIDESPREAD SHOWERS WILL AFFECT MUCH OF
THE FORECAST AREA TOWARDS THE END OF THE FORECAST PERIOD THROUGH
THE REST OF THE DAY SUNDAY, HOWEVER LOWER CONFIDENCE ON TIMING AND
LOCATIONS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...HINTZ
AVIATION...DYE
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