168
FXUS63 KUNR 171114
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
414 AM MST MON FEB 17 2025
KEY MESSAGES
- BITTER COLD TEMPERATURES ACROSS THE AREA THROUGH THURSDAY
MORNING, ESPECIALLY THE SOUTH DAKOTA PLAINS. ALTHOUGH WINDS WILL
BE RELATIVELY LIGHT THROUGH MUCH OF THE PERIOD, WIND CHILL
VALUES WILL FALL TO -15 TO NEAR -45F AT TIMES ACROSS MUCH OF THE
FORECAST AREA DURING THIS TIME.
- A PERIOD OF PROLONGED, LIGHT-TO-MODERATE SNOWFALL WILL CONTINUE INTO
TUESDAY, ESPECIALLY AFFECTING NORTHEASTERN WYOMING, THE BLACK
HILLS, AND SOUTHWESTERN SOUTH DAKOTA. SNOWFALL AMOUNTS OF 2 TO 6
INCHES, WITH SPOTTY HIGHER AMOUNTS, WILL BE POSSIBLE IN THESE
AREAS OVER THE 2-DAY PERIOD.
- LINGERING LIGHT SNOW WILL COME TO AN END DURING THE MIDWEEK PERIOD.
THEREAFTER, A WARMING TREND WILL TAKE PLACE TOWARD THE END OF
THE WEEK, AND ESPECIALLY THE WEEKEND.
DISCUSSION
(TODAY THROUGH SUNDAY)
ISSUED AT 255 AM MST MON FEB 17 2025
CURRENT SURFACE ANALYSIS SHOWS ARCTIC FRONT REMAINING ALONG THE
LEE OF THE ROCKIES, WITH ARCTIC HIGH CENTERED OVER CENTRAL CANADA.
UPPER LEVEL ANALYSIS SHOWS LOW PRESSURE OVER FAR SOUTHWEST
ONTARIO, WITH NORTHWEST FLOW ACROSS OUR REGION. EMBEDDED ENERGY IN
THE FLOW IS INTERACTING WITH TIGHTENING BAROCLINIC ZONE IN PLACE
FROM SOUTHERN MT TO THE BLACK HILLS AREA AND ACROSS NE TO PRODUCE
PERSISTENT LIGHT SNOW AND FLURRIES FROM MUCH OF NORTHEAST WY TO
SOUTHWEST INTO SOUTH CENTRAL SD. SNOWFALL IS A BIT HEAVIER AT
TIMES ACROSS MOSTLY FAR SOUTHWEST SD. CURRENT TEMPS RANGE FROM 20
BELOW TO 25 BELOW ACROSS PORTIONS OF FAR NORTHWEST SD, WHERE THERE
IS THIN HIGH CLOUD COVER, TO AROUND 0 ACROSS MUCH OF NORTHEAST
WY, FAR SOUTHWEST SD AND INTO SOUTH CENTRAL SD. WIND CHILL VALUES
RANGE FROM ABOUT 10 BELOW IN THE WARMER SPOTS TO 30 BELOW TO 40
BELOW ACROSS FAR NORTHWEST SD. WINDS ARE LIGHT IN MOST AREAS,
GENERALLY LESS THAN 10 MPH.
BITTER COLD AIRMASS REMAINS ACROSS THE AREA THROUGH THE MIDDLE PART
OF THE WEEK. EXTREME COLD WARNING WILL REMAIN ACROSS FAR NORTHWEST
SD THROUGH AT LEAST WEDNESDAY MORNING. VALUES THERE WILL RISE ABOVE
WARNING CRITERIA AT TIMES DURING THE DAY AND EARLY EVENING, BUT STAY
AT LEAST NEAR THE ADVISORY RANGE MUCH OF THE TIME. COLD ADVISORY
CONTINUES ACROSS THE REST OF THE NORTHWEST, WEST CENTRAL AND SOUTH
CENTRAL SD PLAINS THROUGH LATE MORNING, WITH WIND CHILL VALUES OF 20
BELOW TO AROUND 30 BELOW AT TIMES. SOME IMPROVEMENT TO ABOVE
ADVISORY CRITERIA CAN BE EXPECTED INTO THE AFTERNOON AS TEMPERATURES
SLOWLY RISE TO AROUND ZERO OR THE LOW SINGLE DIGITS. ADDITIONAL COLD
HEADLINES WILL BE ISSUED LATER TODAY FOR TONIGHT, WITH AN EXTREME
COLD WARNING LIKELY COVERING MORE OF THE SD PLAINS TONIGHT INTO
TUESDAY. WILL TAKE IT ON A DAY TO DAY BASIS AT THIS POINT FOR COLD
HEADLINES ACROSS MOST OF THE AREA, BUT EXPECTING SOME COLD HEADLINES
FOR AT LEAST PORTIONS OF THE FORECAST AREA THROUGH THURSDAY MORNING.
LIGHT SNOW WILL CONTINUE PRETTY STEADILY, THOUGH THERE COULD BE
BREAKS AT TIMES, FROM MUCH OF NORTHEAST WY TO THE BLACK HILLS AREA
AND ACROSS SOUTHWEST INTO SOUTH CENTRAL SD THROUGH AT LEAST TUESDAY
MORNING. SOME LIGHT SNOW AND FLURRIES WILL PUSH ACROSS AREAS FURTHER
NORTH AND EAST OF THE BLACK HILLS AT TIMES AS WELL, ESPECIALLY
TONIGHT INTO TUESDAY MORNING, AS PASSING WEAK DISTURBANCES HELP TO
SQUEEZE OUT ANY AVAILABLE MOISTURE. SNOWFALL AMOUNTS HAVE MOSTLY
BEEN AROUND AN INCH OR LESS SO FAR ACROSS THE WINTER WEATHER
ADVISORY AREA, WITH ADDITIONAL AMOUNTS OF MOSTLY 2 TO 5 INCHES
THROUGH TUESDAY. SOME LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE
ACROSS FAR SOUTHWEST SD WITH ANY PROLONGED PERIODS OF HEAVIER
BANDED SNOWFALL.
SNOWFALL WILL TAPER OFF SOMETIME ON TUESDAY INTO TUESDAY NIGHT AS
TIGHTER BAROCLINIC ZONE SHIFTS FURTHER SOUTH/SOUTHEAST OF THE AREA.
UPPER LOW WILL MOVE SOUTHEAST ACROSS EASTERN PORTIONS OF THE
NORTHERN PLAINS AND UPPER MIDWEST TUESDAY NIGHT AND WEDNESDAY, ALONG
WITH THE ARCTIC HIGH MOVING SOUTH INTO THE NORTHERN PLAINS, HELPING
TO BRING SOME OF THE COLDEST AIR DURING THIS TIME. WINDS WILL BE
QUITE LIGHT, BUT SOME CLEARING SKIES AND FRESH SNOW COVER IN MANY
AREAS WILL BRING SOME VERY COLD TEMPERATURES TUESDAY NIGHT AND EVEN
WEDNESDAY NIGHT OVER AT LEAST EASTERN PORTIONS OF THE CWA, POSSIBLY
NEAR RECORD IN SOME AREAS. MILDER AIR FINALLY STARTS TO BUILD INTO
THE AREA THURSDAY, AND ESPECIALLY FOR FRIDAY AND THE WEEKEND.
SCOURING OUT OF THE ARCTIC AIR COULD BE SLOW AT FIRST, AT LEAST FOR
THURSDAY ACROSS THE SD PLAINS, WITH SNOW COVER AND SOUTHEASTERLY
WINDS IN PLACE. HOWEVER, TEMPS SHOULD BE NEAR OR ABOVE AVERAGE IN
MOST AREAS OVER THE WEEKEND, WITH SOME 50S LIKELY FOR SUNDAY AND THE
FIRST HALF OF NEXT WEEK.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 412 AM MST MON FEB 17 2025
WIDESPREAD LIGHT SNOW WILL CONTINUE THROUGH TUESDAY ACROSS
NORTHEAST WY INTO SOUTH CENTRAL SD. EXPECT MAINLY MVFR CONDS WITH
LOCAL IFR CONDS AT TIMES. VFR CONDS ACROSS NORTHWEST SD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...EXTREME COLD WARNING UNTIL 11 AM MST WEDNESDAY FOR SDZ001-002-
014-078.
COLD WEATHER ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING
FOR SDZ012-013-025-031-032-043-046-047-049-072-073-077.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR SDZ026>030-
041-042-044-074>076.
WY...WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR WYZ058-059.
DISCUSSION/KEY MESSAGES...26
AVIATION...JC
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