471
FXUS63 KUNR 311137
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
537 AM MDT MON MAR 31 2025
KEY MESSAGES
- A SERIES OF DISTURBANCES WILL BRING CHANCES FOR RAIN/SNOW TO THE
REGION THROUGH MUCH OF THE WEEK
- A STRONGER SYSTEM WILL BRING HIGH CHANCES OF RAIN AND SNOW TO
THE REGION TUESDAY AFTERNOON INTO WEDNESDAY, WITH SNOW
ACCUMULATIONS POSSIBLE TUESDAY NIGHT/WEDNESDAY MORNING,
ESPECIALLY ACROSS THE HIGHER ELEVATIONS.
- TEMPERATURES TO REMAIN MAINLY BELOW SEASONAL NORMS THROUGH THE
WEEK.
DISCUSSION
(TODAY THROUGH SUNDAY)
ISSUED AT 255 AM MDT MON MAR 31 2025
CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE GREAT LAKES,
WITH HIGH PRESSURE STILL OVER SOUTH CENTRAL CANADA. NEARLY
STATIONARY FRONTAL BOUNDARY REMAINS NEAR THE LEE OF THE ROCKIES AT
THIS TIME. UPPER LEVEL ANALYSIS SHOWS NEAR ZONAL FLOW FROM THE
PACIFIC NW TO THE UPPER MIDWEST. EMBEDDED ENERGY CONTINUES TO PASS
ACROSS THE REGION, KEEPING CONSIDERABLE CLOUDINESS AND A FEW
FLURRIES IN PLACE. TEMPS ARE MOSTLY IN THE UPPER 20S AND LOWER 30S
WITH LIGHT WINDS.
AN UNSETTLED AND COOL WEEK IS IN STORE AS A SERIES OF UPPER LEVEL
DISTURBANCES CONTINUE TO CROSS THE REGION. THE NEXT DISTURBANCE WILL
ARRIVE LATER TODAY AND TONIGHT AS FRONTAL BOUNDARY NUDGES EASTWARD
AS A WARM FRONT. TEMPS WILL BE WARMER TODAY THOUGH STILL BELOW
SEASONAL AVERAGES, WITH HIGHS MOSTLY IN THE 40S TO NEAR 50 DEGREES.
CHANCES FOR SHOWERS WILL INCREASE LATE IN THE DAY AND ESPECIALLY THE
EVENING AS THE DISTURBANCE APPROACHES. COULD EVEN BE A LITTLE
THUNDER ACROSS WESTERN AREAS LATE DAY/EARLY EVENING. MOST OF THE
PCPN SHOULD BE IN THE FORM OF RAIN WITH WARMER AIR ALOFT, WITH
POSSIBLY A LITTLE SNOW ACROSS THE HIGHEST ELEVATIONS OF THE BLACK
HILLS TONIGHT. AS TEMPS DROP TO AROUND FREEZING ACROSS NORTHWEST SD
LATER TONIGHT/EARLY TUESDAY, THERE COULD BE SOME LIGHT FREEZING RAIN
IN SPOTS.
AS THIS SYSTEM SHIFTS AWAY TO THE NORTHEAST TUESDAY MORNING,
ANOTHER STRONGER SYSTEM WILL BE QUICK ON ITS HEELS LATER TUESDAY
INTO TUESDAY NIGHT. HIGHS ON TUESDAY WILL BE IN THE UPPER 30S AND
40S, WITH CHANCES FOR PCPN INCREASING AGAIN IN THE AFTERNOON FROM
THE WEST. A STRONGER TROUGH WILL MOVE ACROSS OUR AREA AND DEVELOP AN
UPPER LOW AS IT MOVES EAST-NORTHEAST OF THE REGION LATER TUESDAY
NIGHT AND WEDNESDAY. SURFACE LOW IS PROGGED TO DEVELOP OVER THE
CENTRAL HIGH PLAINS AND TRACK EAST THEN NORTHEAST INTO THE UPPER
MIDWEST. AT THIS TIME, THE GFS AND ITS ENSEMBLES ARE FURTHER NORTH
AND STRONGER WITH THE SYSTEM COMPARED TO THE EC, WITH THE CANADIAN
CLOSER TO THE EC. ENSEMBLE AVERAGES FOR PCPN WITH THESE MODELS HAVE
BEEN TRENDING DOWN OVER THE LAST 2 TO 3 RUNS FOR OUR AREA, WITH
QUITE A BIT LESS SHOWN IN THE EC ENSEMBLES. IT APPEARS THAT THE
BETTER FORCING IS POTENTIALLY SHIFTING MORE TO THE EAST AND
NORTHEAST OF OUR CWA WITH EACH RUN, FROM PARTS OF EASTERN SD INTO
NORTHERN MN. PCPN WILL MOSTLY START OFF AS RAIN ON THE PLAINS
TUESDAY AFTERNOON, WITH HIGHER ELEVATION SNOW DEVELOPING OVER THE
BLACK HILLS. AS SOME COLDER AIR GETS WRAPPED INTO THE AREA, SNOW
LEVELS WILL DROP LATE TUESDAY AND TUESDAY NIGHT. THE HEAVIEST PCPN
FOR THE AREA LOOKS TO MOSTLY BE IN THE LATER AFTERNOON AND EVENING,
THEN LIGHTER PCPN LATE TUESDAY NIGHT INTO WEDNESDAY. PCPN AND
SNOWFALL AMOUNTS ARE STILL VERY UNCERTAIN AT THIS POINT. LREF PROBS
FOR 0.25" OR MORE OF PCPN TUESDAY AFTERNOON THROUGH WEDNESDAY
MORNING ARE 40 TO OVER 80 PERCENT ACROSS MUCH OF THE AREA, WITH
0.50" OR MORE RANGING FROM 10 TO OVER 50 PERCENT, HIGHEST PROBS FOR
EACH OVER THE NORTHERN BLACK HILLS. THE BETTER SNOWFALL POTENTIAL
WILL BE ACROSS THE HIGHER ELEVATIONS, WITH 70 PERCENT OR HIGHER
POTENTIAL FOR 3+ INCHES OVER THE NORTHERN BLACK HILLS AND 20 TO OVER
50 PERCENT CHANCES FOR 6+ INCHES. ELSEWHERE, MOSTLY MINOR
ACCUMULATIONS LOOK POSSIBLE, ESPECIALLY ACROSS NORTHEAST WY AND
PARTS OF NORTHWEST SD. WILL CONTINUE TO MONITOR TRENDS AND
POTENTIAL.
THE REST OF THE WEEK LOOKS MILDER AND LESS UNSETTLED, WITH
TEMPERATURES CLOSER TO SEASONAL AVERAGES BY THE END OF THE WEEK. THE
BEST CHANCES FOR PCPN LOOK TO BE LATER THURSDAY INTO FRIDAY WITH A
COUPLE OF WEAKER DISTURBANCES. A MAINLY DRY AND MILDER PATTERN IS
INCREASINGLY LIKELY TO DEVELOP OVER THE WEEKEND AND ESPECIALLY BY
EARLY NEXT WEEK.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 534 AM MDT MON MAR 31 2025
MVFR TO LOCAL LIFR CONDITIONS WILL PERSIST THROUGH THE FIRST HALF
OF THE TAF PERIOD, PARTICULARLY FOR WESTERN SOUTH DAKOTA
(INCLUDING KRAP) AND THE BLACK HILLS. LIGHT RAIN AND SNOW WILL
MOVE BACK INTO THE AREA THIS EVENING AND OVERNIGHT, REDUCING
CEILINGS AND VISIBILITY TO IFR AND LIFR CONDITIONS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...26
AVIATION...15
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