407
FXUS63 KUNR 280908
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
308 AM MDT THU AUG 28 2025
KEY MESSAGES
- ISOLATED TO SCATTERED SHOWERS POSSIBLE THIS AFTERNOON, SEVERE
WEATHER IS NOT EXPECTED.
- MORE WIDESPREAD PRECIPITATION CHANCES POSSIBLE OVER THE WEEKEND.
- TEMPERATURES TO REMAIN AROUND AVERAGE THROUGH THE NEXT WEEK
DISCUSSION
(TODAY THROUGH WEDNESDAY)
ISSUED AT 306 AM MDT THU AUG 28 2025
CURRENT RADAR IMAGERY SHOWS ISOLATED SHOWER ACTIVITY
OVER NORTHWESTERN SD INTO SOUTHEASTERN MT. WATER VAPOR IMAGERY SHOWS
MONSOONAL MOISTURE WRAPPING AROUND WEAK UPPER LEVEL RIDGE AND
STREAMING INTO THE NORTHERN PLAINS. AN UPPER LOW SITS OVER THE
PACIFIC NORTHWEST. 500MB VORT MAX WILL MOVE THROUGH THE REGION
TODAY, BRINGING CHANCES FOR SHOWERS AND STORMS THIS AFTERNOON AND
EVENING. MARGINAL INSTABILITY (SB CAPE OF 500-1500 J/KG) WILL BE IN
PLACE OVER SOUTHERN SD INTO NORTHEASTERN WY THIS AFTERNOON, HOWEVER
DEEP LAYER SHEAR WILL BE WEAK, PRECLUDING ANY CHANCES FOR ORGANIZED
CONVECTION AND SEVERE WEATHER.
SERIES OF DISTURBANCES CONTINUES TO MOVE THROUGH THE NORTHERN PLAINS
FRIDAY INTO SATURDAY AS THE UPPER LOW DRIFTS EASTWARD. CHANCES FOR
SHOWERS AND STORMS WILL CONTINUE INTO THE WEEKEND, WITH SEVERE
POTENTIAL REMAINING VERY LOW. PWAT VALUES OF 1-1.5" WILL SUPPORT
HEAVY RAINFALL IN THE STRONGER UPDRAFTS. LREF GRAND ENSEMBLE PAINTS
70-90+% PROBS OF TOTAL PRECIP THROUGH THE WEEKEND EXCEEDING 0.25"
OVER MUCH OF THE CWA. DETERMINISTIC OUTPUT SHOWS SOME SPOTS OVER THE
WESTERN SD PLAINS COULD PICK UP 0.75-1.0" QPF BY MONDAY MORNING.
UPPER RIDGE BUILDS OVER THE WESTERN US LATE IN THE WEEKEND INTO
EARLY NEXT WEEK, WHICH WILL MEAN A DRIER PATTERN FOR THE BEGINNING
OF NEXT WEEK. MAY SEE A SLIGHT WARM UP EARLY NEXT WEEK AS RIDGE
TRIES TO STRENGTHEN, BUT OVERALL EXPECT AVERAGE TEMPERATURES
(70S TO 80S) THROUGH THE FORECAST PERIOD.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1122 PM MDT WED AUG 27 2025
ISO SHOWERS REMAIN IN NORTHEAST CORNER OF WY. COULD STICK AROUND
THROUGH NIGHT, LIMITED POPS TO TAF SITES. INCREASING SHOWER AND
STORM COVERAGE THROUGH THURSDAY BEGINNING WEST OF BLACK HILLS AS
EARLY AS 12Z AND EXPANDING E THROUGH THE AFTERNOON AND EVENING
HOURS. LOCAL AND BRIEF MVFR/IFR CONDITIONS POSSIBLE WITH HEAVIER
PRECIP, OTHERWISE IFR THROUGH PERIOD. WINDS VAR OVERNIGHT
BECOMING MORE E TO SE THROUGH THE DAY THURSDAY.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...WONG
AVIATION...MARLOW
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