456
FXUS63 KUNR 131912
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
112 PM MDT TUE OCT 13 2026
KEY MESSAGES
- COLD TONIGHT, ESPECIALLY NORTHWESTERN SD WHERE A FREEZE WARNING
IS IN EFFECT. COLDER AIR OVERNIGHT THURSDAY WITH WIDESPREAD
FREEZING TEMPERATURES.
- PRECIPITATION CHANCES TONIGHT THROUGH WEDNESDAY; HEAVIEST
AMOUNTS ALONG NE/SD BORDER.
- BREEZY THURSDAY WITH WIND ADVISORY (45+ MPH GUSTS) WINDS
POSSIBLE (~55%).
- ABOVE AVERAGE TEMPERATURES RETURN FOR THE WEEKEND.
DISCUSSION
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 107 PM MDT TUE OCT 13 2026
WATER VAPOR IMAGERY HIGHLIGHTS A CLOSED LOW CENTERED IN SOUTHERN
NV. FURTHER UPSTREAM, A STRONG VORT MAX IS LOCATED JUST OFF THE BC
COASTLINE WITH UPPER LEVEL MOISTURE STREAMING INTO WESTERN
CANADA. SURFACE HIGH PRESSURE HAS SETTLED ACROSS EASTERN
MT/WESTERN ND WITH TEMPERATURES ACROSS THE FORECAST AREA IN THE
40S. LOW CLOUDS WILL LINGER THROUGH THE AFTERNOON, LIMITING HIGH
TEMPERATURE POTENTIAL TO THE MID TO UPPER 40S FOR MOST OF THE AREA
AND LOW TO MID 50S ACROSS SOUTHERN SD. TEMPERATURES ARE FORECAST
TO FALL BELOW FREEZING ACROSS PORTIONS OF HARDING, PERKINS, AND
ZIEBACH COUNTIES, PARTICULARLY CLOSER TO THE SD/ND BORDER; HAVE
ISSUED A FREEZE WARNING FOR THESE COUNTIES. CLOUD COVER MAY BE A
LIMITING FACTOR, HOWEVER, ENOUGH CLEARING IS EXPECTED ACROSS THIS
AREA FOR TEMPERATURES TO BOTTOM OUT. SOUTH OF THE WARNED AREA,
CLOUD COVER IS EXPECTED TO KEEP TEMPERATURES ABOVE FREEZING AND
LIMIT THE POTENTIAL OF FROST DEVELOPMENT.
CHANCES FOR PRECIPITATION INCREASE WEDNESDAY MORNING INTO THURSDAY
AS THE CLOSED LOW EJECTS INTO THE CENTRAL PLAINS. MOST OF THE RAIN
WILL BE CONFINED TO AREAS ALONG AND SOUTH OF I-90 WHERE 0.5-0.75"+
OF RAIN POSSIBLE FOR SOUTHERN CAMPBELL/WESTON COUNTIES IN WY AND
AREAS ALONG THE SD/NE BORDER.
THE NORTHERN STREAM WAVE THAT IS CURRENTLY LOCATED OFF THE BC COAST
WILL SWING THROUGH SOUTHERN CANADA INTO THE NORTHERN PLAINS AND
UPPER MIDWEST LATE WEDNESDAY INTO THURSDAY WITH A COLD FRONT TO PUSH
THROUGH THURSDAY. AS HAS BEEN THE CASE FOR A FEW DAYS, CONSIDERABLE
SPREAD REMAINS AMONG DETERMINISTIC AND ENSEMBLE GUIDANCE REGARDING
THE ULTIMATE STRENGTH OF THE WINDS BEHIND THE FRONT. THE STRONGEST
CORE OF 850-750 MB WINDS ARE FORECAST TO REMAIN DISPLACED TO OUR
NORTH AND EAST, COINCIDING WITH THE GREATEST COLD AIR ADVECTION.
FORECAST SOUNDINGS HIGHLIGHT POTENTIAL FOR WIND ADVISORY LEVEL
WINDS (WIND GUSTS > 45 MPH) ACROSS NORTHWESTERN SD THROUGH THE
WESTERN SD PLAINS THURSDAY AFTERNOON. OVERALL FORECAST CONFIDENCE
REMAINS LOW, HOWEVER. THE NBM CONTINUES TO FORECAST HIGH WIND
STRENGTH WINDS(GUSTS > 60 MPH), WHICH SEEM OVERDONE AND UNLIKELY
GIVEN THE INGREDIENTS THAT WILL BE IN PLACE.
CLEARING SKIES AND COLD AIR BEHIND THE FRONT WILL RESULT IN
WIDESPREAD SUB-FREEZING TO FREEZING TEMPERATURES ACROSS THE FORECAST
AREA THURSDAY NIGHT INTO FRIDAY MORNING. MUCH WARMER THIS WEEKEND
WITH HIGHS IN THE 60S AND 70S AS UPPER RIDGING BUILDS OVER THE
WESTERN HALF OF THE US.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 1128 AM MDT TUE OCT 13 2026
WIDESPREAD MVFR TO LOCALIZED IFR CONDITIONS ARE BEING REPORTED
AROUND THE AREA THIS MORNING. THESE CONDITIONS WILL LINGER INTO
THE AFTERNOON, SLOWLY TRENDING UP FROM NORTHEAST TO SOUTHWEST.
THAT BEING SAID, MVFR DUE TO LOW CLOUDS MAY LINGER OVER PORTIONS
OF THE NORTHEAST WY PLAINS, THE BLACK HILLS, AND SW SD THROUGH
MUCH OF THE PERIOD GIVEN WEAK FLOW AND LINGERING LOW LEVEL
MOISTURE.
IF THERE IS ANY IMPROVEMENT TO HIGH-END MVFR TO VFR LATE THIS
AFTERNOON, CONDITIONS WILL LOWER AGAIN OVERNIGHT AS THE NEXT ROUND
OF RAIN AND MOISTURE STREAMS INTO THE AREA FROM THE SOUTHWEST.
UNR WATCHES/WARNINGS/ADVISORIES
SD...FREEZE WARNING FROM 2 AM TO 8 AM MDT WEDNESDAY FOR SDZ001-002-
014-078.
WY...NONE.
DISCUSSION...SE
AVIATION...GS
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