477
FXUS63 KUNR 171125
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
425 AM MST TUE DEC 17 2024
KEY MESSAGES
- A WEAK DISTURBANCE WILL BRING AREAS OF LIGHT SNOW OVER MUCH OF THE
AREA THROUGH THE MIDDAY HOURS, WITH ACCUMULATIONS MOSTLY AN INCH
OR LESS.
- A CLIPPER SYSTEM WILL BRING SOME CHANCES FOR LIGHT MIXED PCPN ACROSS
MAINLY NORTHWEST SD WEDNESDAY NIGHT AND POTENTIALLY STRONG
NORTHWEST WINDS ACROSS THE SOUTH DAKOTA PLAINS ON THURSDAY.
- MOSTLY DRY CONDITIONS ARE EXPECTED LATE WEEK AND OVER THE WEEKEND,
WITH TEMPERATURES NEAR TO ABOVE AVERAGE ACROSS MOST OF THE AREA.
DISCUSSION
(TODAY THROUGH MONDAY)
ISSUED AT 255 AM MST TUE DEC 17 2024
CURRENT SURFACE ANALYSIS SHOWS COLD FRONT GENERALLY STALLED OUT
ACROSS SOUTHERN MT, FAR NORTHEAST WY, THE BLACK HILLS AREA, AND
ACROSS SOUTHERN SD. UPPER LEVEL ANALYSIS SHOWS NEAR ZONAL FLOW
ACROSS THE REGION, WITH WEAK SHORTWAVE ENERGY MOVING EAST ACROSS
SOUTHEASTERN MT AND NORTHEASTERN WY. SKIES ARE MOSTLY CLOUDY WITH
KUDX RADAR SHOWING SOME LIGHT SNOW DEVELOPING ACROSS THE AREA,
THOUGH SOME OF THIS PCPN ALOFT IS NOT REACHING THE GROUND AT THIS
POINT. TEMPS RANGE FROM SOME UPPER TEENS ACROSS FAR NORTHWEST SD
TO THE LOWER 30S ACROSS PARTS OF NORTHEAST WY AND FAR SOUTHWEST
SD. WINDS ARE MOSTLY LIGHT AND VARIABLE.
SHORTWAVE ENERGY MOVING ACROSS THE REGION THIS MORNING WILL INTERACT
WITH FRONTAL BOUNDARY IN PLACE TO PRODUCE SOME LIGHT SNOW ACROSS A
GOOD PORTION OF THE BLACK HILLS AREA TO CENTRAL SD. MOST AREAS ARE
LIKELY TO SEE A TRACE UP TO AN INCH OF SNOWFALL. HOWEVER, A BAND OF
MID LEVEL FRONTOGENESIS IS PROGGED TO GENERALLY SLIDE ACROSS
PORTIONS OF NORTHWEST/WEST CENTRAL SD TO CENTRAL AND SOUTHEAST SD
THIS MORNING AND EARLY AFTERNOON. THIS IS LIKELY TO HELP TO PRODUCE
AN ENHANCED BAND OF SNOWFALL OVER PORTIONS OF THESE AREAS,
ESPECIALLY NEAR AND TO THE NORTH OF I-90 FROM THE WALL/KADOKA AREAS
AND EASTWARD. SOME OF THESE AREAS EAST OF WALL INTO CENTRAL SD COULD
SEE A COUPLE OF INCHES OF SNOWFALL LATER THIS MORNING INTO MIDDAY.
THIS SHORTWAVE SHOULD QUICKLY SLIDE EAST OF THE AREA DURING THE
EARLY AFTERNOON WITH IMPROVING CONDITIONS FROM WEST TO EAST. HIGHS
TODAY WILL MOSTLY BE IN THE UPPER 20S AND 30S, WARMEST ACROSS FAR
SOUTHWEST SD. LOWS TONIGHT WILL MOSTLY BE IN THE TEENS. PATCHY FOG
COULD DEVELOP IN SOME AREAS LATE TONIGHT/EARLY WEDNESDAY, ESPECIALLY
ACROSS THE WESTERN SD PLAINS.
MILDER WEATHER CAN BE EXPECTED IN MOST AREAS ON WEDNESDAY, WITH
HIGHS MOSTLY IN THE 30S AND 40S, A BIT COOLER TOWARD NORTH CENTRAL
SD. A CLIPPER SYSTEM WILL TRACK SOUTHEAST OUT OF WESTERN CANADA
WEDNESDAY, CROSSING THE NORTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY
MORNING. MOST OF THE ENSEMBLE OUTPUT CONTINUES TO SHOW MUCH OF THE
SHORTWAVE ENERGY AND PCPN REMAINING NORTH OF THE FORECAST AREA.
HOWEVER, SOME OUTPUT SUPPORTS LIGHT PCPN POSSIBLY TRACKING ACROSS
NORTHWEST SD WEDNESDAY NIGHT. FORECAST SOUNDINGS THERE SUPPORT
FREEZING RAIN, RAIN, OR A WINTRY MIX. ANY PCPN MOUNTS ARE EXPECTED
TO BE RATHER LIGHT, BUT WILL CONTINUE TO MONITOR THAT POTENTIAL. THE
ACCOMPANYING COLD FRONT WILL BRING STRONG WINDS TO A GOOD PORTION OF
THE SD PLAINS LATE WEDNESDAY NIGHT AND ESPECIALLY ON THURSDAY.
ADVISORY LEVEL WINDS ARE LIKELY ACROSS A GOOD PORTION OF THE SD
PLAINS, NEAR OR ABOVE 50 PERCENT, WITH AT LEAST LOW PROBS (UP TO 25
PERCENT) FOR A PERIOD OF WARNING LEVEL WIND GUSTS FROM PARTS OF
NORTHWEST TO SOUTH CENTRAL SD. HIGHS ON THURSDAY LOOK TO BE IN THE
UPPER 20S TO LOWER 40S FROM NORTH TO SOUTH.
THE REST OF THE WEEK AND THE WEEKEND LOOK TO BE MAINLY DRY, WITH A
WARMING TREND, AS A RIDGE BUILDS OVER THE ROCKIES LATE IN THE WEEK
AND EVENTUALLY MOVES EAST ACROSS THE PLAINS OVER THE WEEKEND. THIS
WILL EVENTUALLY BRING ABOVE AVERAGE TEMPS TO MOST AREAS BY LATE
WEEKEND, THOUGH IT COULD BE SLOW TO WARM UP TO THE NORTHEAST OF THE
BLACK HILLS LATE WEEK.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 423 AM MST TUE DEC 17 2024
A BAND OF LIGHT SNOW FROM FAR NORTHEASTERN WY TO CENTRAL SD WILL
BRING AREAS MVFR/IFR CONDITIONS INTO THE EARLY AFTERNOON HOURS.
SOME IMPROVEMENT WILL OCCUR LATER THIS AFTERNOON/EVENING, BUT
STRATUS/FOG MAY DEVELOP OVERNIGHT TONIGHT WITH LOCAL MVFR/IFR
CONDITIONS DEVELOPING AGAIN.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...26
AVIATION...HELGESON
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