319
FXUS63 KUNR 011132
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
532 AM MDT TUE APR 1 2025
KEY MESSAGES
- A SERIES OF DISTURBANCES WILL CONTINUE TO BRING CHANCES FOR
RAIN/SNOW TO THE REGION THROUGH MUCH OF THE WEEK
- A STRONGER SYSTEM WILL BRING HIGH CHANCES FOR ACCUMULATING SNOW
TO AREAS FROM NORTHEAST WY TO THE BLACK HILLS AND PARTS OF
NORTHWEST SD. THE MORE SIGNIFICANT SNOWFALL WILL BE ACROSS THE
NORTHERN BLACK HILLS, ESPECIALLY THE HIGHER ELEVATIONS.
- TEMPERATURES WILL REMAIN BELOW SEASONAL NORMS THROUGH THE WEEK,
THEN A WARMER AND DRIER PATTERN DEVELOPS BY EARLY NEXT WEEK.
DISCUSSION
(TODAY THROUGH MONDAY)
ISSUED AT 310 AM MDT TUE APR 1 2025
CURRENT SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY NOW OVER
SOUTHEAST MT AND EASTERN WY, WITH A DEVELOPING WARM FRONT
EXTENDING FROM EASTERN WY INTO THE CENTRAL PLAINS. UPPER LEVEL
ANALYSIS SHOWS TROUGH OVER THE PACIFIC NW INTO THE ROCKIES, WITH
DEVELOPING SOUTHWESTERLY FLOW INTO THE PLAINS. A QUICK MOVING
DISTURBANCE IS MOVING EAST OF THE AREA NOW, WITH SHOWERS ENDING
OVER FAR EASTERN PORTIONS OF THE CWA. ADDITIONAL ENERGY TO THE
SOUTHWEST OF THE AREA IS PRODUCING MORE LIGHT PCPN ACROSS SOUTH
CENTRAL/SOUTHEAST WY. LOW CLOUDS AND AREAS OF FOG HAVE DEVELOPED
AGAIN OVER MOST OF THE FORECAST AREA EARLY THIS MORNING. TEMPS ARE
MOSTLY IN THE 30S WITH BREEZY SOUTH TO SOUTHEAST WINDS OVER
PORTIONS OF THE SD PLAINS.
UNSETTLED AND COOL PATTERN CONTINUES THROUGH THE WEEK, WITH THE
SYSTEM TO THE WEST MOVING ACROSS THE REGION LATE TODAY INTO
WEDNESDAY. MODELS ARE IN A LITTLE BETTER AGREEMENT ON THE EVOLVEMENT
OF THIS SYSTEM AS IT INTENSIFIES ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST TONIGHT INTO WEDNESDAY, BUT STILL A GOOD AMOUNT OF
UNCERTAINTY ON EXACT TRACK AND WHERE/WHEN ANY AREAS OF HEAVIER PCPN
MAY FALL ACROSS THE AREA. RAIN VS SNOW WILL ALSO BE AN ISSUE IN SOME
AREAS, ESPECIALLY EAST AND NORTHEAST OF THE BLACK HILLS. THE MOST
CERTAIN AREA FOR ACCUMULATING SNOWFALL WILL BE ACROSS THE NORTHERN
BLACK HILLS AND THE BEAR LODGE MTS, ESPECIALLY THE HIGHER TERRAIN,
AS TEMPS COOL EARLIEST THERE AND SOME UPSLOPE ENHANCEMENT OF PCPN
CAN BE EXPECTED, ESPECIALLY LATER TONIGHT INTO WEDNESDAY MORNING.
HREF CHANCES FOR 6 INCHES OR MORE OF SNOWFALL ARE 60 PERCENT OR
HIGHER ACROSS THE FAVORED HIGHER TERRAIN OF THE NORTHERN BLACK
HILLS, ESPECIALLY FROM NEAR LEAD TO TERRY PEAK AND CHEYENNE
CROSSING. PROBABILITIES DROPS OFF QUITE A BIT FROM THERE INTO THE
LOWER TERRAIN, BUT CHANCES FOR 3 OR MORE INCHES IS AT OR ABOVE 50
PERCENT ACROSS MUCH OF THE NORTHERN BLACK HILLS INTO THE NORTHERN
FOOTHILLS AND THE WY BLACK HILLS FORECAST ZONES. HAVE ISSUED WINTER
WEATHER ADVISORIES FOR THESE AREAS FOR TONIGHT THROUGH ABOUT
WEDNESDAY MIDDAY. ELSEWHERE, CHANCES FOR 2 INCHES OR MORE IS HIGHEST
OVER CAMPBELL COUNTY AND FAR NORTHEAST WY (40 TO 80 PERCENT) AS WELL
AS THE HIGHER TERRAIN OF THE NORTHWEST INTO WEST CENTRAL SD PLAINS
(30 TO 70 PERCENT). THIS IS WHERE COLDER AIR WILL FILTER IN EARLIEST
TUESDAY NIGHT ON THE PLAINS. ACCUMULATIONS UP TO A FEW INCHES IS
EXPECTED IN MANY OF THESE AREAS TONIGHT INTO WEDNESDAY, WITH LOCALLY
HIGHER AMOUNTS POSSIBLE OVER HIGHER TERRAIN AND WITH ANY HEAVIER
BANDED SNOWFALL. WILL LET LATER SHIFTS HAVE ANOTHER LOOK AND SEE IF
ANY HEADLINES MAY BE NEEDED ELSEWHERE. HOPEFULLY, MANY AREAS WILL
GET SOME BENEFICIAL PCPN OUT OF THIS SYSTEM BEFORE IT EXITS LATER
WEDNESDAY/WEDNESDAY EVENING.
THE REST OF THE WORK WEEK LOOKS LESS UNSETTLED, BUT REMAINING COOL,
AS ACTIVE ZONAL FLOW PERSISTS. ANOTHER PASSING DISTURBANCE WILL
BRING CHANCES FOR LIGHT RAIN AND SNOW LATE THURSDAY INTO FRIDAY. FOR
THE WEEKEND AND BEYOND, IT LOOKS LIKE A PATTERN CHANGE TO MAINLY DRY
AND WARMER CONDITIONS BY LATE WEEKEND/EARLY NEXT WEEK.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 526 AM MDT TUE APR 1 2025
RAIN AND SNOW WILL OVERSPREAD THE AREA THIS MORNING AS A
LARGE STORM SYSTEM CROSSES THE REGION. WIDESPREAD IFR TO LIFR
CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 3 PM MDT
WEDNESDAY FOR SDZ024.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON MDT
WEDNESDAY FOR SDZ025.
WY...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON MDT
WEDNESDAY FOR WYZ057.
DISCUSSION/KEY MESSAGES...26
AVIATION...15
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