873
FXUS63 KUNR 201651
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
951 AM MST MON JAN 20 2025
KEY MESSAGES
-BITTERLY COLD TEMPERATURES AND WIND CHILLS CONTINUE INTO TUESDAY
MORNING
-COLDEST WIND CHILLS THIS MORNING
-CLIPPER WILL BRING WARMER WEATHER TO THE REGION TUESDAY WITH
WIND AND SOME SNOW WEDNESDAY
DISCUSSION
(TODAY THROUGH SUNDAY)
ISSUED AT 134 AM MST MON JAN 20 2025
A BROAD, DEEP UPPER TROUGH COVERS MUCH OF THE CONUS, WITH A COLD
SURFACE HIGH SETTLING SOUTHWARD INTO MONTANA/WYOMING AND THE
DAKOTAS. A SHORTWAVE TROUGH WILL DROP SOUTHWARD ACROSS THE
FORECAST AREA TODAY WITH ANOTHER ROUND OF CAA LEADING TO
BREEZY/WINDY CONDITIONS, ESPECIALLY OVER THE PLAINS OF WESTERN
SOUTH DAKOTA.
THE NORTHWESTERLY WINDS, ALONG WITH TEMPS WELL BELOW ZERO, WILL
SUPPORT DANGEROUS WIND CHILLS OF 35 BELOW OR COLDER THIS MORNING,
COLDEST ACROSS NW SD WHERE SOME PLACES COULD SEE WIND CHILL
READINGS NEAR 50 BELOW. TODAY WILL BE THE COLDEST DAY OF THIS
ARCTIC OUTBREAK WITH HIGH TEMPERATURES REMAINING BELOW ZERO FOR
MUCH OF THE AREA. THE EXTREME COLD WARNING WILL CONTINUE THROUGH
THIS MORNING, THEN AS TEMPERATURES/WIND CHILLS WARM SLIGHTLY,
WILL REPLACE WITH A COLD WEATHER ADVISORY FROM THIS AFTERNOON INTO
TUESDAY MORNING.
ON MONDAY NIGHT, THE ARCTIC HIGH WILL BEGIN TO SHIFT SOUTHEASTWARD
AWAY FROM THE AREA WITH WARMER AIR SPREADING BACK INTO THE REGION
ON TUESDAY AHEAD OF THE NEXT CLIPPER SYSTEM. TEMPERATURES WILL
LIKELY RISE ON MONDAY NIGHT ACROSS NORTHEASTERN WYOMING, AND FAR
WESTERN SOUTH DAKOTA AS PRESSURE FALLS INCREASE AND WESTERLY
DOWNSLOPE WINDS DEVELOP.
ACTIVE NORTHWESTERLY FLOW ALOFT WILL THEN DEVELOP WITH THE FIRST
IN A SERIES OF CLIPPER SYSTEMS AFFECTING THE REGION TUESDAY NIGHT
AND WEDNESDAY. THIS SYSTEM WILL BRING CHANCES FOR LIGHT SNOW ON
THE PLAINS, WITH A ROUND OF UPSLOPE SNOW LIKELY ACROSS THE
NORTHERN BLACK HILLS. GUSTY NORTHWEST WINDS ARE ALSO EXPECTED ON
WEDNESDAY, WITH GUSTS OVER 45 MPH POSSIBLE ON THE WESTERN SOUTH
DAKOTA PLAINS.
ANOTHER CLIPPER IS EXPECTED THURSDAY INTO FRIDAY WITH ANOTHER
ROUND OF SNOW AND WIND EXPECTED. NEGATIVE AO TENDENCIES AFTER
NEXT WEEKEND TEND TO FAVOR ANOTHER POSSIBLE ARCTIC OUTBREAK TOWARD
THE END OF THE MONTH. HOWEVER, THE MAIN CORE OF COLD AIR MAY PASS
EAST OF THE FORECAST AREA WITH TEMP UNCERTAINTY REMAINING HIGH.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 949 AM MST MON JAN 20 2025
SCATTERED TO BROKEN MVFR CLOUDS WILL GRADUALLY CLEAR OUT THIS
AFTERNOON. BREEZY NORTHWEST WINDS WILL PERSIST PERSIST THROUGH THE
AFTERNOON, WITH GUSTS OF UP TO 35 KT ACROSS THE WESTERN SD
PLAINS.
UNR WATCHES/WARNINGS/ADVISORIES
SD...EXTREME COLD WARNING UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR
SDZ001-002-012>014-024>032-041>044-046-047-049-072>078.
COLD WEATHER ADVISORY UNTIL 8 AM MST /9 AM CST/ TUESDAY FOR
SDZ001-002-012>014-024>032-041>044-046-047-049-072>078.
WY...EXTREME COLD WARNING UNTIL 11 AM MST THIS MORNING FOR WYZ054>060.
COLD WEATHER ADVISORY UNTIL 8 AM MST TUESDAY FOR WYZ054>060.
DISCUSSION/KEY MESSAGES...10
AVIATION...POJORLIE
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