085
FXUS63 KUNR 181027
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
327 AM MST SAT JAN 18 2025
KEY MESSAGES
-BITTERLY COLD TEMPERATURES/WIND CHILLS THIS WEEKEND INTO EARLY
NEXT WEEK
-OCCASIONAL LIGHT SNOW EXPECTED TODAY, WITH A COUPLE INCHES OF
ACCUMULATION IN THE NORTHERN BLACK HILLS, MAINLY FLURRIES
ELSEWHERE
DISCUSSION
(TODAY THROUGH FRIDAY)
ISSUED AT 304 AM MST SAT JAN 18 2025
LATEST ANALYSIS SHOWS AN UPPER LOW OVER NORTHWESTERN ONTARIO WITH
A BROAD, DEEP, UPPER TROUGH CONTINUING TO DROP SOUTHWARD OVER THE
GREAT PLAINS. AT THE SURFACE, A BITTERLY COLD HIGH PRESSURE AREA
WILL DROP SOUTHEASTWARD FROM ALBERTA/SASKATCHEWAN EARLY THIS
MORNING, INTO EASTERN MONTANA BY THIS AFTERNOON.
WINDS WILL REMAIN BREEZY TODAY DUE TO STRONG LOW LEVEL COLD
ADVECTION AS THE ARCTIC HIGH SETTLES INTO THE REGION. PERIODS OF
LIGHT SNOW OR FLURRIES WILL OCCUR TODAY. THE BEST CHANCES FOR
LIGHT SNOW ACCUMULATIONS WILL BE OVER NORTHEASTERN WYOMING AND
THE NORTHERN BLACK HILLS, WITH ROUNDS OF ENHANCED LIFT AND
MOISTURE SUPPORTING AN INCREASE IN SNOWFALL AT TIMES.
MUCH COLDER TEMPERATURES ARE EXPECTED TONIGHT AS ARCTIC AIR
SETTLES INTO THE REGION BEHIND THE SECONDARY COLD FRONT. THE
COMBINATION OF WIND AND TEMPERATURES WILL SUPPORT WIND CHILL
READINGS OF 25 TO 35 BELOW ZERO TONIGHT INTO SUNDAY MORNING SO A
COLD WEATHER ADVISORY HAS BEEN ISSUED. THE STRONG ARCTIC HIGH WILL
CONTINUE TO AFFECT THE REGION THROUGH TUESDAY MORNING, WITH TEMPS
LIKELY STRUGGLING ABOVE ZERO FOR MUCH OF THE REGION ON SUNDAY AND
MONDAY.
OVERNIGHT LOW TEMPERATURES RANGING FROM 10-20 BELOW ZERO (LOCALLY
COLDER) ARE EXPECTED SUNDAY, MONDAY AND TUESDAY MORNINGS,
ESPECIALLY WHERE CLEAR SKIES, CALM WINDS, AND SNOW COVER OVERLAP.
HIGHS WILL AGAIN STRUGGLE ABOVE ZERO AT MANY AREAS MONDAY. THIS
WILL LIKELY NECESSITATE THE ISSUANCE OF A EXTREME COLD WARNING
AND/OR COLD WEATHER ADV SUNDAY NIGHT INTO TUES MORNING GIVEN
APPARENT TEMPERATURE FORECASTS OF 25 TO 45 BELOW, COLDEST IN THE
NORTHWEST SD. ARCTIC HIGH WILL BEGIN TO SHIFT SE OUT THE AREA
MONDAY NIGHT WITH WARMER AIR SPREADING BACK INTO THE REGION TUES
AHEAD OF THE NEXT CLIPPER SYSTEM. ACTIVE NW FLOW LOOKS TO DEVELOP
AFTERWARD WITH HIGHLY VARIABLE TEMPS AND INCREASED WIND.
CONFIDENCE IN TEMPS AND WEATHER DROP OFF SHARPLY TOWARD THE END OF
NEXT WEEK DUE TO HIGH VARIABILITY IN MODEL SOLUTIONS. NEGATIVE AO
TENDENCIES BEYOND NEXT WEEK TEND TO FAVOR ANOTHER POSSIBLE ARCTIC
OUTBREAK TOWARD THE END OF THE MONTH.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1017 PM MST FRI JAN 17 2025
BREEZY NORTH-NORTHWEST WINDS WILL PERSIST THROUGH THE EVENING
HOURS WITH SUSTAINED WINDS 10-20 KNOTS WITH GUSTS UP TO 30 KNOTS
AT TIMES. LINGERING LIGHT SNOW/FLURRIES CONTINUE TO TAPER OFF,
WITH ONLY SPOTTY LIGHT SNOW SHOWERS THROUGH THE OVERNIGHT HOURS.
MVFR CEILINGS WILL PERSIST WITH SOME TRANSIENT IMPROVEMENT TO VFR
AT TIMES. BLOWING AND DRIFTING SNOW MAY RESULT IN PERIODS OF
REDUCED SURFACE VISIBILITY.
UNR WATCHES/WARNINGS/ADVISORIES
SD...COLD WEATHER ADVISORY FROM 8 PM MST /9 PM CST/ THIS EVENING TO
11 AM MST /NOON CST/ SUNDAY FOR SDZ001-002-012>014-024>032-
041>044-046-047-049-072>078.
WY...COLD WEATHER ADVISORY FROM 8 PM THIS EVENING TO 11 AM MST SUNDAY
FOR WYZ054>060.
DISCUSSION/KEY MESSAGES...10
AVIATION...SE
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