390
FXUS63 KUNR 251942
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
142 PM MDT SAT OCT 25 2025
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES EXPECTED FOR SUNDAY
- COOLER AND UNSETTLED SUNDAY NIGHT THROUGH TUESDAY MORNING
DISCUSSION
(THIS EVENING THROUGH SATURDAY)
ISSUED AT 134 PM MDT SAT OCT 25 2025
LATEST WATER VAPOR IMAGERY SHOWS CLOSED 500HPA LOW SPINNING ACROSS
OK/KS BORDER WITH RIDGING STRETCHING FROM AZ THROUGH SD AND INTO
CANADA. NEXT 500HPA LONGWAVE TROUGH IS CRASHING ONSHORE THE WRN
CONUS WITH ABUNDANT MOISTURE STREAMING THROUGH THE INTERMOUNTAIN
WEST.
WHILE TEMPERATURES SHOULD STILL BE ABOVE SEASONAL NORMS FOR
SUNDAY, SOUTHWEST FLOW MOVING OVERHEAD AND ASSOCIATED UPPER LEVEL
MOISTURE SHOULD MAKE FOR A MOSTLY CLOUDY SKY ACROSS MUCH OF THE
CWA. 850HPA TEMPS FROM 12-16C WITH SOUTHERLY TO WESTERLY SURFACE
WINDS SHOULD ENSURE ONE MORE NICE DAY. ENSEMBLES ARE SHOWING FROM
60-100% PROBABILITIES OF MAX 2 METER TEMPS GREATER THAN 65F.
PREVIOUS CONCERNS ABOUT FIRE WEATHER DON’T APPEAR TO BE AS BIG AN
ISSUE ANYMORE AS FORECAST RH VALUES ACROSS THE AREA ARE NOW
TRENDING HIGHER THAN PREVIOUSLY FORECAST.
ATTENTION THEN TURNS TO SUNDAY TO TUESDAY MORNING. DETERMINISTIC
MODELS CONTINUE TO OFFER DIFFERING SOLUTIONS ON TIMING AND
LOCATION OF PCPN AND FORM OF PCPN THROUGH THIS PERIOD. AS 500HPA
AND 700HPA TROUGHS APPROACH THE CWA...NUMEROUS WAVES EMBEDDED IN
CYCLONIC FLOW MAKE FOR MESSY FORECAST. BOTH GFS AND NAM ARE
SHOWING IMPRESSIVE 700HPA THETA-E FORCING DURING THE OVERNIGHT
HOURS SUNDAY NIGHT INTO MONDAY MORNING. HOWEVER, BOTH MODELS ARE
NOW SHOWING A SECONDARY 700HPA DROPPING THROUGH THE SOUTHWESTERN
PART OF THE CWA MONDAY EVENING THROUGH TUESDAY MORNING. THERE IS
SOME THETA-E FORCING ASSOCIATED WITH THIS, AND BOTH MODELS ARE NOW
PAINTING AN AREA OF QPF...SNOW ACTUALLY...FALLING THROUGH 12Z
TUESDAY. THE NAM IS NOW THE MORE BULLISH OF THE MODELS SHOWING A
LOT MORE SNOW FALLING IN THE BLACK HILLS AND ACROSS PARTS OF THE
SW SD PLAINS THAN THE GFS YESTERDAY...ALTHOUGH THE OVERALL
FOOTPRINT FROM BOTH MODELS DO LOOK SIMILAR. BOTH MODELS ARE
SIMILAR WITH AN AREA OF 850-700HPA FRONTOGENESIS SLIDING THROUGH
FROM 18Z MONDAY THROUGH 12Z TUESDAY. SO THE QUESTION IS...WILL THE
PCPN BE RAIN OR SNOW THAT FALLS MONDAY EVENING THROUGH TUESDAY
MORNING IN AN AREA FROM THE BLACK HILLS THROUGH THE SW SD PLAINS?
FORECAST SFC WET BULB TEMPS THROUGH THAT TIME PERIOD HANG AROUND
35F LEANING MORE TOWARD A LIQUID EVENT. TO COMPLICATE MATTERS, THE
00Z LREF ENSEMBLES SHOW NO PROBABILITIES OF SNOWFALL, AND KEEPS
THINGS PROGRESSIVE WITH PROBABILITIES UNDER 20% FOR LIQUID PCPN
AFTER 06Z TUESDAY. WITH ALL THE UNCERTAINTY, WILL KEEP WITH
PROGRESSIVE NBM SOLUTION...WITH ALL PCPN ASSOCIATED WITH MAIN COLD
FRONT AS IT SLIDES QUICKLY THROUGH DURING SUNDAY NIGHT THROUGH
MONDAY...KEEPING THE MONDAY NIGHT THROUGH TUESDAY MORNING PERIOD
DRY EXCEPT FOR THE FAR SOUTHEAST CWA.
THINGS LOOK TO BE RELATIVELY DRY THEREAFTER UNTIL THURSDAY WHEN
NEXT SYSTEM IS FORECAST TO DROP THROUGH. THERE STILL REMAINS SOME
RUN TO RUN CONSISTENCY ISSUES WITH THIS SYSTEM BASICALLY REVOLVING
AROUND OVERALL STRENGTH AND SENSIBLE WEATHER.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1115 AM MDT SAT OCT 25 2025
VFR CONDITIONS PREVAIL ACROSS THE AREA THROUGHOUT THE TAF PERIOD.
SKIES WILL REMAIN SKC THROUGH MUCH OF THE PERIOD WITH CLOUDS
INCREASING BY THE LATE AFTERNOON SATURDAY. CEILINGS ARE EXPECTED
TO REMAIN HIGH WITH A CLOUD DECK OF SCT150 DEVELOPING FOR THE
SECOND HALF OF THE PERIOD INTO SUNDAY. BREEZY CONDITIONS PERSIST
WITH A SOUTHERNLY/SOUTHWESTERLY WIND OF 10 TO 15 KNOTS WITH GUSTS
NEAR 25 KNOTS POSSIBLE.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...HINTZ
AVIATION...DZIEWALTOWSKI
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