118
FXUS63 KBIS 271027
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
427 AM CST SAT DEC 27 2025
KEY MESSAGES
- DENSE FOG ACROSS MUCH OF NORTHWEST AND PARTS OF CENTRAL NORTH
DAKOTA THIS MORNING, POTENTIALLY LINGERING INTO THE AFTERNOON.
- HIGH CHANCES OF LIGHTLY ACCUMULATING SNOW AND GUSTY WINDS
TONIGHT, AND REDUCED VISIBILITY WHILE SNOW IS FALLING.
- WIND GUSTS UP TO 45 MPH IN FAR SOUTHWEST AND SOUTH CENTRAL
NORTH DAKOTA LATE THIS AFTERNOON THROUGH TONIGHT.
- GUSTY WINDS AND VERY COLD TEMPERATURES TONIGHT THROUGH SUNDAY
NIGHT, WITH WIND CHILLS AS LOW AS 30 BELOW ZERO POSSIBLE.
DISCUSSION
ISSUED AT 427 AM CST SAT DEC 27 2025
A SIGNIFICANT CHANGE IN THE WEATHER IS EXPECTED THE NEXT 24
HOURS AS AN ARCTIC COLD FRONT CROSSES THE REGION. UNTIL THE
FRONTAL PASSAGE OCCURS TONIGHT, CONCERNS FOR DENSE FOG WILL
PERSIST OVER PARTS OF THE AREA TODAY.
AS OF 10 UTC, DENSE FOG WITH VISIBILITY FROM 1/4SM TO 1/2SM IS
PERSISTING ALONG AND NORTH OF A LINE FROM COLUMBUS IN BURKE
COUNTY TO NEAR GARRISON, CARRINGTON, JAMESTOWN, AND OAKES. THIS
IS GENERALLY ALONG AND NORTH OF A DIFFUSE WARM FRONTAL ZONE,
WHERE LIGHT LOW-LEVEL WINDS, A STRONG LOW-LEVEL INVERSION, AND A
RELATIVELY DEEP LOW-LEVEL SATURATED LAYER PERSISTS. THE FRONTAL
ZONE HAS NUDGED SLIGHTLY NORTHWARD OVERNIGHT, AS EXPECTED, WITH
THE KBIS VAD WIND PROFILER SAMPLING INCREASING AND VEERING
WINDS THAT ARE WEST-SOUTHWEST NEAR 30 KT AROUND 1000 FT AGL THE
LAST FEW HOURS. THIS IS CONSISTENT WITH THE SLOW NORTH-NORTHEAST
PROGRESSION OF THE WARM FRONTAL ZONE, AND RELATED SHALLOWING OF
THE LOW-LEVEL MOISTURE THAT HAS LED TO DISSIPATION OF THE DENSE
FOG IN PARTS OF SOUTH CENTRAL ND. THAT IN TURN HAS ALLOWED US
TO CANCEL PARTS OF THE DENSE FOG ADVISORY IN SOUTH CENTRAL ND
WHERE OBSERVATIONS HAVE SHOWN INCREASED VISIBILITY TRENDS.
HOWEVER, WE ACTUALLY EXTENDED THE END TIME OF THE DENSE FOG
ADVISORY UNTIL 18 UTC (NOON CST) IN NORTH CENTRAL ND INTO THE
JAMES RIVER VALLEY. OVERNIGHT MODEL GUIDANCE HAS SUGGESTED
PERSISTENCE OF THE DENSE FOG LONGER THAN PREVIOUSLY EXPECTED,
ESPECIALLY ACROSS NORTH CENTRAL ND. THIS RESULTS FROM A LONGER
PERIOD OF WEAK LOW-LEVEL FLOW IN THOSE AREAS THAN EARLIER
SIMULATED, EVEN AS FLOW AROUND 850 MB TURNS MORE WESTERLY DURING
THE DAY TODAY. WE EXTENDED A MENTION OF FOG INTO THE AFTERNOON
AND EARLY EVENING IN NORTH CENTRAL ND INTO PARTS OF THE JAMES
RIVER VALLEY, AND IT'S POSSIBLE LATER UPDATES WILL NEED TO
EXTEND SOME PARTS OF THE DENSE FOG ADVISORY PAST 18 UTC.
MEANWHILE, RADAR HAS SHOWN A MODEST INCREASE IN REFLECTIVITY IN
CENTRAL ND THE LAST FEW HOURS IN AN AREA THAT'S BROADLY WITHIN
THE EXIT REGION OF A 100-120 KT 250 MB JET STREAK, IN AN AREA OF
MODEST MIDLEVEL FRONTOGENESIS, AND NEAR THE WEST SIDE OF MID-
LEVEL WARM AIR ADVECTION THAT IS FOCUSED IN NORTHEASTERN ND. THE
STRATUS DECK IN CENTRAL ND HAS APPEARED TO BE A BIT TOO SHALLOW
FOR FREEZING DRIZZLE PRODUCTION DESPITE THE LATTER ASCENT IN THE
FORM OF WARM AIR ADVECTION (UNLIKE IN NORTHEASTERN ND CLOSER TO
GRAND FORKS, WHERE THE STRATUS DECK HAS BEEN DEEPER, INTERSECTING
WITH THAT LOW AND MIDLEVEL ASCENT). NONETHELESS, THE ATTEMPTS
AT PRECIPITATION DEVELOPMENT IN CENTRAL ND ARE WORTHY OF
INCLUDING A LOW (20 PERCENT) CHANCE OF LIGHT FREEZING RAIN THE
FORECAST IN PARTS OF CENTRAL AND MORESO NORTH CENTRAL ND THROUGH
EARLY THIS MORNING. THIS IS VERY CONDITIONAL GIVEN DRY AIR
ALOFT, AND THUS FAR THE RADAR REPRESENTATION WOULD SUGGEST ONLY
LOW ODDS OF ANY PRECIPITATION ACTUALLY REACHING THE GROUND.
HIGHS TODAY WILL RANGE FROM 35 TO 45 F IN SOUTHWEST AND PARTS OF
SOUTH CENTRAL ND, ALONG AND SOUTH OF THE WARM FRONTAL ZONE, TO
THE 20S WHERE STRATUS AND FOG PERSIST IN NORTHERN ND.
THE APPROACHING ARCTIC COLD FRONT IS SURGING THROUGH SOUTHERN
ALBERTA AND INTO NORTH CENTRAL MT AS OF 10 UTC (4 AM CST), WITH
TEMPERATURES IN ITS WAKE RAPIDLY FALLING INTO THE ZERO F RANGE.
GUIDANCE EXPECTS THE SHORTWAVE TROUGH ATTENDANT TO THIS FRONT
AND THE FRONT ITSELF TO REACH WESTERN ND LATE THIS AFTERNOON,
AND TO CROSS CENTRAL ND THIS EVENING. THE FRONT IS FORECAST TO
BE ACCOMPANIED BY STRONG LOW- AND MIDLEVEL COLD AIR ADVECTION,
REFLECTED BY MODERATE TO STRONG ISOTHERM PACKING AT 850 MB, AND
3-HOUR SURFACE PRESSURE RISES OF 8-10 MB CROSSING SOUTHWESTERN
AND SOUTH CENTRAL ND LATE THIS AFTERNOON AND EVENING. MIDLEVEL
WINDS ARE FORECAST TO ONLY PEAK AROUND 35-40 KT, BUT THE COLD
AIR ADVECTION AND STRENGTH OF THE SURFACE PRESSURE RISES ARE
SUPPORTIVE OF GUSTY NORTHWEST WINDS FOLLOWING THE FRONT. THE
STRONGEST WINDS ARE EXPECTED IN FAR SOUTHWESTERN AND SOUTH
CENTRAL ND, WHERE WE HAVE ISSUED A WIND ADVISORY FOR GUSTS UP TO
45 MPH LATE THIS AFTERNOON THROUGH TONIGHT.
A BAND OF LIGHT SNOW IS EXPECTED TO FOLLOW THE FRONT FROM WEST
TO EAST TONIGHT, WITH HIGH PROBABILITIES OF LIGHT SNOW ON THE
ORDER OF A DUSTING TO ONE-HALF INCH. THERE ARE ONLY LOW, ~20%
PROBABILITIES OF AN INCH OR MORE OF ACCUMULATION, THOUGH. THIS
WILL BE DRIVEN BY A SURGE OF LOW- AND MIDLEVEL FRONTOGENESIS
FOLLOWING THE SURFACE FRONTAL PASSAGE, AUGMENTED TO AT LEAST
SOME EXTENT FROM BROAD SYNOPTIC-SCALE ASCENT. SOME BLOWING SNOW
IS ALSO EXPECTED DUE TO THE LIGHT FALLING SNOW AND GUSTY WINDS.
ON SUNDAY, THE COLD ARCTIC AIR MASS WILL BE IN PLACE OVER THE
AREA, AND ENSEMBLE GUIDANCE HAS LOW SPREAD IN CALLING FOR HIGHS
ONLY FROM ZERO TO 10 ABOVE. A NOTABLE SURFACE PRESSURE GRADIENT
WILL EXIST AS A SURFACE LOW RAPIDLY DEEPENS IN THE MIDWEST AND
GREAT LAKES REGION, AND FORECAST SOUNDINGS SHOW A WELL-MIXED
LAYER EXTENDING INTO MIDLEVEL WINDS OF 35 TO 40 KT ACROSS MUCH
OF THE AREA. THE RESULT WILL BE A WINDY DAY, WITH LOW TO MEDIUM
PROBABILITIES OF NEEDING A WIND ADVISORY. WE DO NOTE THAT EFI
VALUES ARE ONLY MARGINALLY SUPPORTIVE OF NEEDING AN ADVISORY,
AND PEAK WINDS IN THE MIXED LAYER ARE ON THE CUSP OF WHAT IS
TYPICALLY ASSOCIATED WITH ADVISORY EVENTS. EITHER WAY, THE WINDS
AND EXPECTED AIR TEMPERATURES WILL RESULT IN A VERY COLD DAY,
WITH WIND CHILLS OF 15 BELOW TO 30 BELOW ZERO ACROSS THE AREA.
WE HAVE MEDIUM TO HIGH CONFIDENCE THAT A COLD WEATHER ADVISORY
WILL EVENTUALLY BE NEEDED FOR PARTS OF THE AREA, ESPECIALLY IN
NORTHWEST ND (PERHAPS BEGINNING TONIGHT). WE WILL, HOWEVER,
ALLOW LATER SHIFTS TO DETERMINE THE EXACT LAYOUT OF WHERE THE
WIND CHILL CRITERIA OF -30 F FOR THE ADVISORY WILL BE MET, AND
FOR HOW LONG.
SURFACE HIGH PRESSURE IS EXPECTED TO CROSS THE AREA ON SUNDAY
NIGHT, RESULTING IN THE COLDEST NIGHT OF THE NEAR TERM, WITH
LOWS CURRENTLY FORECAST TO BE FROM 5 BELOW ZERO TO 15 BELOW
ZERO, COLDEST IN NORTHWESTERN ND. GIVEN THE EXPECTED SURFACE
RIDGE AXIS LOCATION, THE 10TH PERCENTILE NBM LOWS WHICH SHOW
MORE WIDESPREAD LOWS OF 10 BELOW TO 20 BELOW ZERO IS A VERY
REASONABLE POTENTIAL OUTCOME IN SOME AREAS.
ENSEMBLE SPREAD IS RELATIVELY LOW EARLY NEXT WEEK, AND CALLS FOR
A WARMING TREND MONDAY AND TUESDAY AS TRANSIENT RIDGING CROSSES
THE REGION IN MEAN NORTHWEST FLOW ALOFT. BY MIDWEEK, THE SPREAD
IN ENSEMBLE MEMBERS INCREASES AND REMAINS SIGNIFICANT, ON THE
ORDER OF 20 DEGREES (E.G., NBM 25TH TO 75TH PERCENTILE RANGES
FOR HIGH TEMPERATURES AT BISMARCK RANGE FROM -1 F TO 22 F ON
WEDNESDAY/NEW YEARS EVE). THIS IS A RESULT OF UNCERTAINTY IN
HOW AMPLIFIED NORTHWESTERLY FLOW BECOMES IN THAT TIMEFRAME, AND
WHERE AN ASSOCIATED SIGNIFICANT FRONTAL ZONE WINDS UP LOCATED.
THE LARGER-SCALE FLOW UNCERTAINTY STEMS FROM DIFFERING OUTCOMES
IN THE SPEED AND AMPLITUDE OF A TROUGH IN THE EASTERN PACIFIC,
WITH A ROUGHLY 50/50 PERCENT PROBABILITY OF EITHER A WARMER OR
COOLER SCENARIO LOCALLY IN THE LATEST ENSEMBLE CLUSTER ANALYSIS.
DESPITE THE UNCERTAINTY, THE ENSEMBLE CONSENSUS SUPPORTS MEDIUM
CHANCES OF LIGHT SNOW ALONG AND NORTH OF THE AFOREMENTIONED
BAROCLINIC ZONE, AND WE ARE INCLUDING THEM IN THE FORECAST FOR
THE PERIOD CENTERED ON WEDNESDAY.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 427 AM CST SAT DEC 27 2025
WIDESPREAD IFR TO LIFR CEILINGS WITH DENSE FOG WILL PERSIST
ACROSS MUCH OF NORTHWEST AND PARTS OF CENTRAL NORTH DAKOTA
THROUGH THE DAY TODAY OVERNIGHT.
A PERIOD OF LOW-LEVEL WIND SHEAR HAS BEEN ADDED TO THE KBIS TAF
THROUGH ABOUT 13Z DUE TO WEST-SOUTHWEST WINDS AROUND 30 KT THAT
HAVE DEVELOPED AROUND 1000 FT AGL.
A COLD FRONT IS FORECAST TO CROSS THE STATE FROM NORTHWEST TO
SOUTHEAST THIS AFTERNOON AND EVENING, BRINGING GUSTY NORTHWEST
WINDS AND A PERIOD OF FALLING SNOW TO MOST TERMINALS, ALONG WITH
LOW CEILINGS RETURNING ACROSS SOUTHERN NORTH DAKOTA.
BIS WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NDZ001>005-010>013-
021>023-025-036-037-048-051.
WIND ADVISORY FROM 4 PM CST /3 PM MST/ THIS AFTERNOON TO 6 AM
CST /5 AM MST/ SUNDAY FOR NDZ040>045.
DISCUSSION...CJS
AVIATION...HOLLAN/CJS
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