743
FXUS63 KUNR 290908
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
308 AM MDT FRI AUG 29 2025
KEY MESSAGES
- UNSETTLED CONDITIONS TO START OFF THE HOLIDAY WEEKEND.
- COOL FOR THE WEEKEND, THEN WARMING TO SEASONABLE TEMPS FOR NEXT
WEEK.
DISCUSSION
(TODAY THROUGH THURSDAY)
ISSUED AT 306 AM MDT FRI AUG 29 2025
WATER VAPOR IMAGERY DEPICTS WEAK UPPER LOW OVER NORTHEASTERN
WY/SOUTHEASTERN MT. SCATTERED SHOWERS ARE ONGOING ACROSS
NORTHWESTERN AND SOUTHWESTERN SD, CIRCULATING AROUND A WEAK SFC
LOW. COULD SEE A FEW LIGHTNING STRIKES IN SOME OF THE STRONGER
CELLS BUT GENERALLY EXPECTING RAIN SHOWERS THROUGH THE REST OF THE
NIGHT. SCATTERED SHOWERS WILL CONTINUE THROUGH THE DAY TODAY AS
THE SFC LOW DRIFTS TO THE EAST. MARGINAL INSTABILITY DEVELOPS THIS
AFTERNOON AS SB CAPE RISES TO 750-1000 J/KG THIS AFTERNOON.
HOWEVER NOT TOO CONCERNED ABOUT SEVERE WEATHER AS WEAK DEEP LAYER
SHEAR WILL BE UNSUPPORTIVE OF ORGANIZED CONVECTION.
SCATTERED SHOWERS AND STORMS WILL CONTINUE THROUGH SATURDAY AS A
SERIES OF DISTURBANCES MOVES THROUGH THE NORTHERN PLAINS. PWAT
VALUES OF 1-1.5" (150 TO 200% OF NORMAL) WILL SUPPORT HEAVY
RAINFALL IN THE STRONGER UPDRAFTS. LREF GRAND ENSEMBLE OUTPUT
PAINTS 70-90+% PROBS OF GREATER THAN 0.25" QPF OVER MUCH OF
WESTERN SD BY 12Z SUNDAY MORNING. THERE ARE CHANCES FOR TOTAL
PRECIP TO EXCEED 1", PRIMARILY OVER THE I-90 CORRIDOR INTO SOUTH
CENTRAL SD (30-40% PROBS). SOME SPOT COULD SEE UP TO 1.5" OR MORE
WHERE STORMS TRAIN.
CONDITIONS DRY OUT BY SUNDAY AS THE UPPER LEVEL RIDGE BUILDS BACK
INTO THE WESTERN US, LEAVING THE NORTHERN PLAINS UNDER DRY,
NORTHWEST FLOW. CAN'T COMPLETELY RULE OUT SOME ISOLATED AND
DIURNALLY DRIVEN SHOWERS/STORMS OVER THE BLACK HILLS THROUGH
WEDNESDAY AS THE RIDGE SITS OVER THE WESTERN US.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY MORNING)
ISSUED AT 1110 PM MDT THU AUG 28 2025
UNSETTLED WEATHER WILL IMPACT FLYING CONDITIONS THROUGH THIS TAF
ISSUANCE. SCATTERED SHOWERS AND STORMS ARE EXPECTED INTERMITTENTLY,
WITH THE BEST CHANCES FOR THUNDERSTORM ACTIVITY FRIDAY AFTERNOON AND
EVENING. VFR CONDITIONS ARE EXPECTED TO BE THE PREDOMINANT FLIGHT
RULES; HOWEVER, WHERE HEAVIER DOWNPOURS OCCUR, VISIBILITY MAY
BRIEFLY DROP AS LOW AS 2 MILES. THERE ARE SOME HINTS AT LOWER
CEILINGS TOWARD THE VERY END OF THE TAF PERIOD WITH UPSLOPE FLOW AND
STEADILY INCREASING MOISTURE. THIS WOULD MOST LIKELY IMPACT KRAP.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...WONG
AVIATION...COOLEY
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