186
FXUS63 KUNR 262251
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
351 PM MST FRI DEC 26 2025
KEY MESSAGES
- MILD WITH GUSTY WEST/SOUTHWEST WINDS THROUGH SATURDAY MORNING,
THEN GUSTY NORTHWEST WINDS BEHIND AN ARCTIC COLD FRONT LATER
SATURDAY INTO SUNDAY ACCOMPANIED BY SOME LIGHT PRECIPITATION
- WIND CHILLS 0 TO -25F BY SUNDAY MORNING
- TEMPERATURES BOUNCE BACK NEXT WEEK, BUT WITH LOW CONFIDENCE
GIVEN CWA PROXIMITY TO ARCTIC BOUNDARY
DISCUSSION
(THIS EVENING THROUGH FRIDAY)
ISSUED AT 206 PM MST FRI DEC 26 2025
21Z SURFACE ANALYSIS HAD LOW PRESSURE ENTERING NORTH CENTRAL MT
WITH A WARM FRONT INTO NORTHEAST NE. 50S/MID 60S BEHIND IT WITH
40S AHEAD OF IT OVER THE CWA. DECENT PRESSURE FALLS OVER MT/WY
SUPPORTING GUSTY SOUTHWEST WINDS AGAIN, EXTENDING INTO THE BLACK
HILLS/HIGHER FOOTHILLS. WATER VAPOUR LOOP HAD UPPER TROUGH OVER
SOUTHWEST CANADA/NORTHWEST CONUS, WHICH WILL BE OUR NEAR-TERM
FORECAST CONCERN.
TODAY/SATURDAY MORNING, UPPER TROUGH MOVES INTO THE NORTHERN
ROCKIES WITH EMBEDDED SHORTWAVE STRENGTHENING OVER THE
MT/ND/CANADIAN BORDER. MILD WEATHER WILL CONTINUE WITH GUSTY
WEST/SOUTHWEST WINDS AT TIMES. TEMPERATURES WILL BE ABOVE GUIDANCE
IN THE WEST AND NEAR FOR THE EAST.
SATURDAY AFTERNOON THROUGH SUNDAY, EMBEDDED SHORTWAVE MORPHS INTO
UPPER LOW AS IT MOVES INTO THE GREAT LAKES. SURFACE LOW DEVELOPS
OVER MT AND THEN ZIPS INTO THE CENTRAL PLAINS AS IT DEEPENS. THE
LOW WILL DRAG AN ARCTIC COLD FRONT THROUGH THE CWA WITH MODERATE
ISALLOBARIC FORCING (3-5MB/HR PRESSURE RISES) SATURDAY NIGHT ALONG
WITH A NARROW BAND OF POST-FRONTAL FRONTOGENETIC
FORCING/MOISTURE. SHOULD SEE A BAND OF LIGHT SNOW (PERHAPS BRIEFLY
STARTING AS LIGHT RAIN) ZIP THROUGH THE CWA WITH GUSTY NORTHWEST
WINDS. LATEST GUIDANCE SUGGESTS THE MOST LIKELY OUTCOME WILL BE A
HIGH-END WIND ADVISORY FROM K2WX-KRAP GIVEN FORECAST SOUNDINGS AND
SQUEEZE ZONE. PROBABILISTIC GUIDANCE AT ODDS WITH REGARD GUST
POTENTIAL. HREF CHANCE >50MPH GUSTS VERY LOW, BUT NBM PAINTS
40-70% CHANCE 45-55MPH GUSTS, WHICH IS MORE IN LINE WITH
TRADITIONAL MOS GUIDANCE, ALSO MATCHING SUBJECTIVE PATTERN
RECOGNITION. GIVEN DISCREPANCIES, WILL HOLD OFF ON ANY HEADLINES
WITH MAIN EVENT STARTING AFTER 28/00Z. OTHER IMPACT WILL BE
PLUMMETING APPARENT TEMPERATURES, SOME 40-60 DEGREES COLDER THAN
SATURDAY AFTERNOON AS WIND CHILLS DROP TO 0 TO -25F BY SUNDAY
MORNING. TIME TO THROW ON YOUR FAVORITE WINTER WEATHER GEAR.
TEMPERATURES WILL BE NEAR GUIDANCE/10-20F BELOW NORMAL.
NORTHWEST FLOW ALOFT IS EXPECTED FOR MOST OF NEXT WEEK WITH A
SERIES OF WEAK DISTURBANCES PUSHING/PULLING THE ARCTIC BOUNDARY
IN/NEAR THE CWA WITH INCREASING FORECAST TEMPERATURE SPREADS. LOW
CONFIDENCE TEMPERATURE FORECAST, BUT OVERALL, SLIGHTLY ABOVE IN
THE SOUTHWEST AND PROBABLY COLDER THAN NORMAL IN THE NORTHEAST.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 351 PM MST FRI DEC 26 2025
VFR CONDITIONS WILL PERSIST THROUGH THE FORECAST PERIOD. BREEZY WEST
TO SOUTHWEST WINDS WILL CONTINUE ACROSS PORTIONS OF NORTHEASTERN
WY INTO THE BLACK HILLS WITH GUSTS OF 30-35 KT.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...HELGESON
AVIATION...WONG
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