765
FXUS63 KUNR 151102
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
402 AM MST SAT FEB 15 2025
KEY MESSAGES
- LIGHT SNOW/FLURRIES CONTINUE AT TIMES THROUGH MUCH OF TODAY, WITH
ADDITIONAL ACCUMULATIONS UP TO AROUND AN INCH FOR MOST OF
NORTHEASTERN WY AND WESTERN SD.
- FRIGID AIR WILL REMAIN ACROSS THE REGION THROUGH AT LEAST THE MIDDLE
OF NEXT WEEK, WITH THE COLDEST AIR AND MOST DANGEROUS WIND
CHILLS EXPECTED DURING THE FIRST HALF OF THE WEEK. SOME RECORD
COLD TEMPERATURES POSSIBLE EARLY NEXT WEEK ACROSS THE SD PLAINS.
- ANOTHER ROUND OF SNOWFALL IS LIKELY SUNDAY NIGHT THROUGH
TUESDAY, WITH IMPACTFUL ACCUMULATIONS POSSIBLE FROM NORTHEAST
WY TO SOUTHWEST SD, THEN A WARMING TREND AND DRIER PATTERN IS
EXPECTED THURSDAY THROUGH SATURDAY.
DISCUSSION
(TODAY THROUGH FRIDAY)
ISSUED AT 230 AM MST SAT FEB 15 2025
CURRENT SURFACE ANALYSIS SHOWS ARCTIC FRONT WELL SOUTH OF THE
FORECAST AREA, WITH LOW PRESSURE ALONG IT ACROSS NORTHEAST CO.
CANADIAN HIGH PRESSURE IS LOCATED ACROSS NORTHERN AB. UPPER LEVEL
ANALYSIS SHOWS WEST-NORTHWEST FLOW ACROSS THE REGION, WITH
SHORTWAVE TROUGH PASSING ACROSS THE CENTRAL PLAINS. WEAKER
NORTHERN STREAM ENERGY IS IMPACTING OUR AREA, WITH LIGHT SNOW AND
FLURRIES ACROSS MUCH OF NORTHEAST WY AND WESTERN SD. ANY
ACCUMULATIONS SO FAR HAVE BEEN QUITE LIGHT. TEMPS ARE MOSTLY IN
THE SINGLE DIGITS AND LOWER TEENS, WITH NEAR OR BELOW ZERO WIND
CHILLS, AS NORTH TO NORTHEAST WINDS ARE NOTED OVER MOST OF THE
AREA.
LIGHT SNOW/FLURRIES WILL CONTINUE AT TIMES THROUGH MUCH OF TODAY,
WITH ACCUMULATIONS UP TO AROUND AN INCH IN MOST AREAS. SOME
LOCATIONS, ESPECIALLY FAR NORTHEAST WY TO THE BLACK HILLS, COULD SEE
UP TO A COUPLE INCHES OF FLUFFY SNOWFALL. SNOWFALL SHOULD TAPER OFF
IN MOST AREAS BY MID TO LATE AFTERNOON. BREEZY NORTHERLY WINDS LATER
TODAY COULD CAUSE PATCHY BLOWING SNOW AND SOME DRIFTING ON THE
PLAINS. TEMPS TODAY WILL NOT BUDGE MUCH, WITH HIGHS IN THE SINGLE
DIGITS TO MID TEENS. LOWS TONIGHT WILL DROP TO THE SINGLE DIGITS
BELOW ZERO IN MOST AREAS, WITH SOME COLDER SPOTS ACROSS NORTHWEST
SD. MINIMUM WIND CHILLS VALUES WILL MOSTLY BE 10 BELOW TO NEAR 30
BELOW, LOWEST GENERALLY OVER FAR NORTHWEST SD.
FRIGID AIRMASS WILL REMAIN ACROSS THE REGION THROUGH THE MIDDLE OF
NEXT WEEK, WITH TEMPS WELL BELOW AVERAGE. A REINFORCING SHOT OF
ARCTIC AIR IS EXPECTED TO GRADUALLY PUSH INTO THE REGION SUNDAY
NIGHT AND MONDAY. AT THIS POINT, HIGHS WILL STRUGGLE TO GET ABOVE
ZERO ACROSS AT LEAST MUCH OF THE SD PLAINS MONDAY AND TUESDAY,
POSSIBLY WEDNESDAY AS WELL, ESPECIALLY NORTH AND EAST OF THE BLACK
HILLS. LOWS WILL BE WELL BELOW ZERO, WITH DANGEROUS WIND CHILLS OF
20 BELOW TO AROUND 40 BELOW ZERO EXPECTED AT TIMES IN MANY AREAS
DURING THE OVERNIGHT AND MORNING HOURS. WINDS WILL BE BREEZY IN
SPOTS MONDAY AS THE COLDER AIR PUSHES IN, BUT RELATIVELY LIGHT AFTER
THAT. FOR NOW, WILL ISSUE AN EXTREME COLD WATCH FOR FAR NORTHWEST SD
FROM SUNDAY NIGHT INTO WEDNESDAY. THIS IS WHERE THE POTENTIAL FOR
COLDEST TEMPS/WIND CHILLS ARE EXPECTED. A COLD WEATHER ADVISORY
COULD BE NEEDED LATER TONIGHT FOR THAT AREA AS WELL, BUT WILL LET
DAYSHIFT HAVE ANOTHER LOOK.
ADDITIONAL SNOWFALL IS EXPECTED WITH THE REINFORCING SHOT OF ARCTIC
AIR SUNDAY NIGHT AND MONDAY. THE MORE PERSISTENT SNOWFALL WILL BE
WHERE ENERGY ALOFT INTERACTS WITH TIGHTER BAROCLINIC ZONE IN PLACE
ACROSS THE REGION FROM LATER SUNDAY NIGHT INTO TUESDAY. AT THIS
POINT, IT LOOKS TO SET UP MOST FAVORABLY FOR MORE IMPACTFUL
ACCUMULATIONS FROM NORTHEAST WY TO THE BLACK HILLS AND SOUTHWEST SD.
LREF CHANCES FOR AT LEAST AN INCH OF SNOWFALL ARE 70 TO NEAR 100
PERCENT ACROSS THESE AREAS, WITH 20 TO OVER 50 PERCENT CHANCES FOR 3
INCHES OR MORE IN MOST OF THE SAME AREAS DURING THIS TIME. THESE
PERCENTAGES ARE BASED ON ABOUT 10:1 SNOW RATIOS, SO WITH THE FLUFFY
SNOWFALL EXPECTED (UP TO AROUND 20:1), THE PERCENTAGES FOR THESE
AMOUNTS WILL GENERALLY BE HIGHER. BOTH EC AND GFS HAVE BOUNCED
AROUND A BIT WITH REGARD TO WHERE THE TIGHTER BAROCLINIC ZONE SETS
UP DURING THIS PERIOD, WHICH WOULD AFFECT WHERE THE BETTER SNOWFALL
POTENTIAL WILL BE. WILL CONTINUE TO MONITOR OVER THE NEXT COUPLE OF
DAYS. MILDER AIR WILL EVENTUALLY RETURN TO THE REGION LATE NEXT
WEEK, BUT HOW QUICKLY AND TO WHAT EXTENT IS STILL UNCERTAIN. GFS
ENSEMBLE OUTPUT IS STILL FASTER WITH SCOURING OUT THE COLDEST AIR
COMPARED TO THE EC THURSDAY INTO FRIDAY, BUT BOTH SHOW AT LEAST NEAR
AVERAGE TEMPERATURES RETURNING NEXT WEEKEND.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 358 AM MST SAT FEB 15 2025
AREAS OF MVFR/IFR CONDITIONS WITH LIGHT SNOW WILL CONTINUE
THROUGH THIS MORNING WITH LOCAL LIFR CONDITIONS POSSIBLE AROUND
THE BLACK HILLS. THE SNOW WILL GRADUALLY END FROM WEST TO EAST
LATE THIS MORNING THROUGH THIS AFTERNOON. MAINLY VFR CONDITIONS
ARE EXPECTED BY EARLY EVENING. HOWEVER, SOME LOCAL MVFR CEILINGS
MAY LINGER INTO TONIGHT, ESPECIALLY AROUND THE BLACK HILLS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...EXTREME COLD WATCH FROM SUNDAY EVENING THROUGH WEDNESDAY MORNING
FOR SDZ001-002-014-078.
WY...NONE.
DISCUSSION/KEY MESSAGES...26
AVIATION...7
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