821
FXUS63 KUNR 302311
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
511 PM MDT SUN MAR 30 2025
KEY MESSAGES
-LIGHT SNOW WILL CONTINUE INTO THE EVENING OVER FAR WESTERN SD
INTO NORTHEAST WY, WITH LITTLE TO NO ACCUMULATION EXPECTED
-A SERIES OF DISTURBANCES WILL BRING CHANCES FOR RAIN/SNOW TO THE
REGION THROUGH MUCH OF THE WEEK
-A STRONGER DISTURBANCE WILL BRING A GOOD CHANCE OF RAIN AND SNOW
TO THE REGION TUES, WITH SNOW ACCUMULATIONS POSSIBLE TUES NIGHT
-TEMPERATURES TO REMAIN MAINLY BELOW SEASONAL NORMS THROUGH THE
WEEK
DISCUSSION
(THIS EVENING THROUGH SUNDAY)
ISSUED AT 149 PM MDT SUN MAR 30 2025
POTENT PAC UPPER JET CONTINUES TO SUPPORT UNSETTLED FLOW OVER THE
PAC, BRINGING A SERIES OF IMPULSES INTO THE WESTERN CONUS. THIS
PATTERN WILL CONTINUE THROUGH THE WEEK, WITH SEVERAL ROUNDS OF PAC
SYSTEMS INTO THE REGION. WEAK IMPULSE CONTINUES TO MOVE EAST
ACROSS THE REGION TODAY WITH ANOTHER AROUND OF LIGHT SNOW MOVING
ACROSS NORTHEAST WY AND FAR WESTERN SD. LIGHT SNOW WILL MOVE EAST
AND DIMINISH THROUGH EVENING, WITH LITTLE TO NO ACCUMS EXPECTED.
COOL AND MOIST EASTERLY UPSLOPE FLOW WILL CONTINUE OVERNIGHT WITH
WIDESPREAD LOW CLOUDS. PATCHY FOG WILL ALSO BE POSSIBLE ALONG THE
NORTH AND EAST SLOPES OF THE BLACK HILLS. DEEPER TROUGH WILL MOVE
INTO THE WESTERN CONUS MONDAY AND SUPPORT INCREASING RETURN FLOW
OVER THE REGION. GUSTY SOUTHEAST WINDS WILL DEVELOP MONDAY WITH
SOME GUSTS OVER 40 MPH POSSIBLE ACROSS FAR NW SD. TEMPS WILL
STRUGGLE INTO 30S/40S GIVEN CLOUD COVER AND MOIST UPSLOPE FLOW,
WITH THE WARMEST TEMPS IN WESTERN CAMPBELL COUNTY WHERE THE BL
WILL MIX OUT. WEAK IMPULSE WILL TRAVERSE THE FLOW AHEAD OF THIS
SYSTEM WITH ASSOCIATED STEEP LAPSE RATES AND WILL SUPPORT
SCATTERED RAIN OR SNOW SHOWERS OVER THE WESTERN THIRD. ISOLATE
THUNDERSTORMS WILL ALSO BE POSSIBLE FROM NORTHEAST WY INTO FAR
SOUTHWEST SD IN THE LATE AFTERNOON AND EARLY EVENING. THIS AREA OF
LIFT WILL SUPPORT SLIGHTLY BETTER CHANCES FOR MOSTLY RAIN ON THE
SD PLAINS MONDAY NIGHT WHERE POS THETA-E ADV WILL ENSUE. SOME
FREEZING RAIN OR SNOW WILL ALSO BE POSSIBLE ACROSS NW SD A WELL,
HINGING ON HOW THE THERMAL FIELDS SET UP. THE MAIN/STRONGER WAVE
WILL PUSH OUT OF THE ROCKIES TUE AND SUPPORT A GOOD CHANCE OF RAIN
AND SNOW OVER THE REGION. RAIN WILL CHANGE TO SNOW TUE NIGHT WITH
SOME POTENTIAL FOR CONCENTRATED BANDING PER STEEP MID LEVEL
LAPSES RATES AND A STRONG FGEN SIGNAL. LOW CONFIDENCE REMAINS PER
DETAILS WRT THIS SYSTEM, GIVEN POOR MODEL CONSENSUS AND THE FACT
THAT SNOW AMOUNTS WILL LIKELY BE DRIVEN BY MESOSCALE PROCESSES.
AFTER WED, THINGS DRY OUT WITH JUST SOME CHANCES FOR SHOWERS AT
TIMES AS SEMI-UNSETTLED WESTERLY FLOW CONTINUES. TEMPS WILL ALSO
MODERATE SOME BY THE END OF THE WEEK, BUT STILL REMAIN AROUND
SEASONAL NORMS.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 509 PM MDT SUN MAR 30 2025
LIGHT SNOW WILL SLOWLY TAPER OFF THROUGH THE EVENING HOURS, WITH
SNOW ENDING FROM WEST TO EAST AFTER 01-04Z. OTHERWISE, LINGERING
LOW CLOUDS AND FOG WILL RESULT IN MVFR TO LIFR CONDITIONS THROUGH
THE 10-12Z, BEFORE GRADUAL IMPROVEMENT IS EXPECTED TO TRANSIENT
VFR AND MVFR CONDITIONS MONDAY MORNING INTO THE AFTERNOON HOURS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...JC
AVIATION...SE
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