899
FXUS63 KUNR 180446
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
946 PM MST TUE DEC 17 2024
KEY MESSAGES
- PATCHY FREEZING FOG POSSIBLE TONIGHT ACROSS THE WESTERN SD
PLAINS
- 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
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 234 PM MST TUE DEC 17 2024
UPPER AIR ANALYSIS SHOWS A LONGWAVE TROUGH CROSSING THE CENTRAL
CONUS. THE MAIN AXIS HAS SHIFTED EAST OF THE CWA, WITH SNOW ACROSS
EASTERN SD AND SOUTHERN MN. KUDX RADAR AND SURFACE OBS DO SHOW SOME
LINGERING LIGHT SNOW SHOWERS ACROSS FAR NORTHWEST SD. THIS PRECIP
WILL END LATE THIS AFTERNOON. SURFACE HIGH PRESSURE IS BUILDING IN
FROM THE NORTHWEST. QUIET WEATHER IS EXPECTED TONIGHT, WITH LIGHT
WINDS. MODELS ARE SHOWING THE POSSIBILITY FOR PATCHY FREEZING FOG
AFTER 06Z ACROSS PORTIONS OF THE WESTERN SD PLAINS, PERSISTING TO
JUST AFTER SUNRISE. QUIET WEATHER WILL CONTINUE THROUGH WEDNESDAY.
WARM AIR ADVECTION LATE TONIGHT THROUGH THE DAY TOMORROW WILL BRING
HIGHS AROUND 30 IN CENTRAL SD TO NEAR 50 ACROSS SW SD AND NE WY. A
FAST-MOVING CLIPPER SYSTEM WILL CROSS THE NORTHERN ROCKIES TOMORROW,
THEN THE DAKOTAS WEDNESDAY NIGHT. THIS WILL BRING A QUICK SHOT OF
PRECIPITATION MAINLY TO ND AND EAST RIVER, BUT IT LOOKS LIKE
NORTHWEST SD TO THE BLACK HILLS MAY GET CLIPPED. CAMS SHOW RAIN/SNOW
SHOWERS CROSSING NW SD DURING THE WEDNESDAY EVENING HOURS. WITH THE
WARMING LOW LEVELS AND GROUND TEMPERATURES BELOW FREEZING, SOME
FREEZING RAIN WILL BE POSSIBLE. QPF WILL BE VERY LIGHT, AND
TEMPERATURES ARE EXPECTED TO WARM TO NEAR OR ABOVE FREEZING BY 06Z,
SO THAT WILL ALSO LIMIT ANY POTENTIAL ICING IMPACTS. BEHIND THE
WAVE, A COLD FRONT WILL CROSS THE AREA EARLY THURSDAY MORNING.
STRONG NW WINDS WITH GUSTS TO 50-55 MPH ARE POSSIBLE MAINLY ACROSS
WESTERN TO CENTRAL SD. RIGHT NOW IT LOOKS LIKE A HIGH-END WIND
ADVISORY EVENT, BUT THERE SOME POTENTIAL FOR GUSTS TO 60 MPH OVER
FAR NW SD. WILL LET LATER SHIFTS REASSESS. STRONG UPPER RIDGING
BUILDS ACROSS THE REGION FOR THE END OF THE WEEK, BRINGING DRY AND
MILD CONDITIONS TO THE AREA.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 943 PM MST TUE DEC 17 2024
STRATUS/FOG MAY DEVELOP OVERNIGHT TONIGHT ON THE NW SD PLAINS,
WITH LOCAL MVFR/IFR CONDITIONS DEVELOPING AND PERSISTING THROUGH
THE MORNING HOURS. OTHERWISE, VFR CONDS ELSEWHERE. A STRONG
CLIPPER SYSTEM WILL APPROACH THE REGION WED EVENING WITH
INCREASING FLOW OFF THE SFC. THIS WILL SUPPORT LOCAL WIND SHEAR IN
THE LEE OF THE BLACK HILLS BEFORE THE SFC FRONT MOVES THROUGH. IN
ADDITION, LIGHT RAIN OR FREEZING RAIN WILL BE POSSIBLE ACROSS NW
SD WED EVENING.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...13
AVIATION...JC
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