763
FXUS63 KUNR 201758
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1058 AM MST TUE JAN 20 2026
KEY MESSAGES
- LIGHT SNOW ACROSS NORTHWESTERN SD, NORTHERN BLACK HILLS TODAY
- GUSTY WINDS THIS AFTERNOON, STRONGER WINDS WEDNESDAY, BOTH OF
WHICH MAY CAUSE LOCAL BLOWING SNOW WHERE SNOW IS PRESENT
- BRIEF BOUT OF ARCTIC AIR BY FRIDAY, BUT STRENGTH AND DURATION
TENUOUS
DISCUSSION
(TODAY THROUGH MONDAY)
ISSUED AT 208 AM MST TUE JAN 20 2026
09Z SURFACE ANALYSIS HAD FRONTAL BOUNDARY FROM CENTRAL MT INTO
THE NE PANHANDLE WITH LOW PRESSURE ALONG IT OVER CENTRAL MT. FEW
RADAR RETURNS ALOFT UNDER MID-CLOUDS STREAMING INTO THE CWA AHEAD
OF THE NEXT SHORTWAVE NOTED OVER CENTRAL AB/SK PER WATER VAPOUR
LOOP. 100KT JET STREAK SCOOTING IT ALONG. EFFECTS OF ACTIVE
NORTH/NORTHWEST FLOW ALOFT AND ASSOCIATED CLIPPERS REMAIN THE MAIN
FORECAST CONCERN.
TODAY, SHORTWAVE RACES SOUTHEAST ALLOWING MT LOW TO DEEPEN
SLIGHTLY AS IT MOVES THROUGH CWA ALONG FRONTAL BOUNDARY. MAIN
LIFT/MOISTURE NORTHEAST OF BOUNDARY WHERE STRIPE OF MODEST
ISENTROPIC LIFT NOTED, NUDGED ALONG BY MODEST MID-LEVEL QG-FORCING
BUBBLE. EXPECT A BAND OF LIGHT SNOW (50% CHANCE 0.1" QPF) ACROSS
NORTHWESTERN SD AND THEN SOME UPSLOPE-ENHANCEMENT (FROUDE>1, 0-2KM
RH ~90% FROM 20/18Z-21/03Z) FOR THE BLACK HILLS AS TRAILING COLD
FRONT SHIFTS SOUTH. PERHAPS A COUPLE OF INCHES OF SNOW FOR THE
NORTHERN BLACK HILLS. OTHER IMPACT WILL BE 2-4MB/3HR PRESSURE
RISES BEHIND COLD FRONT THAT WILL TAP INTO 25-40KT LOWEST 2KM
NORTHWEST FLOW. DECENT SETUP FOR WIND ADVISORY FROM K2WX-KRAP
(40-70% CHANCE >45MPH GUSTS), SO HAVE HOISTED. SOME BLOWING SNOW
MAY OCCUR WHEN SNOW IS PRESENT WITH THE HIGHER WINDS, BUT WSSI
ISN'T TERRIBLY EXCITED ABOUT THE PROSPECT PER MINOR IMPACTS
PAINTED. TEMPERATURES WILL BE NEAR GUIDANCE.
TONIGHT/WEDNESDAY, STRONGER SHORTWAVE CAREENS SOUTHEAST OUT OF
CANADA INTO THE UPPER MIDWEST. IT WILL DRAG A FAST-MOVING COLD
FRONT INTO THE CWA EARLY WEDNESDAY WITH 3-6MB/3HR PRESSURES RISES
BEHIND IT. LOWEST 0-2KM DEPICTS 30-50KT WINDS WITH MODEST COLD AIR
ADVECTION/SUBSIDENCE RESULTING IN THE POTENTIAL FOR HIGH WINDS
(40-70% CHANCE >55MPH GUSTS) ON THE PLAINS OF WESTERN SD. DOESN'T
LOOK LIKE THE HIGHER WINDS WILL LAST TOO LONG PER FORECAST BUFKIT
SOUNDINGS. MOISTURE/FORCING WILL BE SCANT, SO NOT EXPECTING MUCH
NEW SNOW. GIVEN COLDER TEMPERATURES AND POTENTIAL NEW SNOW FROM
TODAY, BLOWING SNOW MAY BE MORE OF AN ISSUE. WILL KEEP MESSAGING
SIMPLE THIS MORNING (WITH A WIND ADVISORY OUT) AND LET LATER
SHIFTS HONE POTENTIAL HEADLINES FOR TOMORROW. TEMPERATURES WILL BE
NEAR GUIDANCE.
THURSDAY/FRIDAY, ARCTIC AIR WILL OOZE INTO THE NORTHERN PLAINS
WITH ~1051MB HIGH BUBBLING INTO THE NORTHERN PLAINS. WE'LL BE ON
THE WESTERN EDGE OF THE COLDEST AIR, SO CONFIDENCE IN STRENGTH OF
ARCTIC AIR STILL IN QUESTION. RIGHT NOW, FRIDAY LOOKS TO BE THE
COLDEST WITH POTENTIAL COLD ADVISORY (LREF CHANCE <-25F APPARENT
TEMPERATURE 50%+ FROM K2WX-KICR) HEADLINES. REAL MOISTURE IS
SCANT.
LOOKING TOWARD THE WEEKEND, WE'LL CONTINUE TO BE ON THE EDGE OF
THE COLDEST AIR WITH TEMPERATURES SPREADS 15-25F, BUT WITH MEAN
TEMPERATURES INCREASING. CONFIDENCE IN DETAILS REMAIN LOW.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 1041 AM MST TUE JAN 20 2026
A COLD FRONT IS FORECAST TO MOVE THROUGH THE REGION TODAY AND
BRING INCREASING WINDS FROM THE NORTHWEST. IN ADVANCE OF THE
FRONTAL PASSAGE, WINDS WILL BE GENERALLY LIGHT IN THE 5 TO 10 MPH
RANGE. AS THE FRONT PASSES THE AREAS TERMINALS, WINDS WILL
INCREASE QUICKLY WITH GUSTS FROM 30-45KTS EXPECTED. IN ADDITION
TO THE FRONTAL PASSAGE, LOW LEVEL WIND SHEAR WILL ALSO BE A
CONCERN OVERNIGHT. SURFACE WINDS WILL REMAIN GUSTY THROUGH THE
OVERNIGHT AND INTO WEDNESDAY MORNING.
THE FRONT WILL ALSO BRING AREAS SNOW SHOWERS PRIMARILY OVER THE
BLACK HILLS AND NORTHWESTERN SD. WHERE SNOW OCCURS MVFR TO LOCALLY IFR
VISIBILITIES ARE ANTICIPATED WITH MVFR TO LOW END VFR
CEILINGS.FLIGHT CONDITIONS DUE TO RESTRICTIONS FROM SNOW AND LOW
CEILINGS WILL IMPROVE BY TONIGHT GENERALLY AROUND 00Z.
UNR WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY UNTIL 6 PM MST THIS EVENING FOR SDZ001-012-013-031-
041-072-073.
WY...NONE.
DISCUSSION/KEY MESSAGES...HELGESON
AVIATION...HATCH
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