336
FXUS63 KBIS 260959
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
359 AM CST FRI DEC 26 2025
KEY MESSAGES
- AREAS OF FOG ARE EXPECTED TODAY AND TONIGHT, WITH DENSE FOG
EXPECTED THIS MORNING FROM NORTHWEST INTO PARTS OF CENTRAL
NORTH DAKOTA.
- THERE IS A LOW (20%) CHANCE OF LIGHT FREEZING RAIN IN FAR
NORTHWEST AND NORTH CENTRAL NORTH DAKOTA TONIGHT.
- MEDIUM TO HIGH CHANCES OF LIGHT SNOW AND GUSTY WINDS ARE
EXPECTED SATURDAY NIGHT, WITH VERY COLD TEMPERATURES
RETURNING SATURDAY NIGHT THROUGH SUNDAY NIGHT.
DISCUSSION
ISSUED AT 359 AM CST FRI DEC 26 2025
EARLY THIS MORNING, A BROAD SURFACE RIDGE AXIS EXTENDS ACROSS
CENTRAL ND, WITH TRANSIENT, LOW-AMPLITUDE SHORTWAVE RIDGING
ALOFT IN THE WAKE OF THE IMPULSE THAT BROUGHT HIGH-IMPACT
FREEZING RAIN TO PARTS OF THE AREA LATE YESTERDAY. SURFACE
PRESSURE FALLS ARE BEGINNING FROM WESTERN SASKATCHEWAN INTO
NORTHEASTERN MT IN ADVANCE OF THE NEXT UPSTREAM IMPULSE ALOFT.
AN EXPANSIVE STRATUS DECK WITH AREAS OF FOG EXISTS OVER MUCH OF
THE AREA, WITH THE MOST SIGNIFICANT/WIDESPREAD DENSE FOG BEING
NOTED ON THE WEST EDGE OF THE RIDGE AXIS, AND NEAR THE WEST SIDE
OF THE STRATUS DECK, ROUGHLY FROM WILLISTON TO WATFORD CITY,
HAZEN, GLEN ULLIN/NEW SALEM, AND FORT YATES AS OF 09 UTC.
EARLIER WE ISSUED A DENSE FOG ADVISORY FROM NORTHWESTERN INTO
PARTS OF CENTRAL ND, WHERE ASOS/AWOS VISIBILITY OBSERVATIONS AND
WEB CAM IMAGERY HAS SHOWN THE MOST WIDESPREAD AND RELATIVELY-
PERSISTENT VISIBILITY OF 1/2SM OR LESS. THAT SAID, EVEN WITHIN
THAT CORRIDOR THERE HAS BEEN SOME VARIABILITY/FLUCTUATIONS IN
VISIBILITY TRENDS AT TIMES. THIS MAY BE DUE TO A SOMEWHAT
SHALLOW LOW-LEVEL MOIST LAYER, AND/OR SUBTLE INCREASES IN MIXING
OF THE BOUNDARY LAYER AS FLOW JUST ABOVE THE SURFACE STARTS TO
INCREASE ON THE WEST SIDE OF THE RIDGE AXIS. NONETHELESS, THE
OVERALL SCENARIO FAVORS CONTINUATION IF NOT ADDITIONAL EXPANSION
OF DENSE FOG FROM NORTHWEST INTO PARTS OF CENTRAL ND, ESPECIALLY
ALONG AND JUST WEST OF THE MISSOURI RIVER WHERE LOW CEILINGS
INTERSECT SLIGHTLY HIGHER TERRAIN. A CONSENSUS OF RECENT CAMS
AND GLAMP GUIDANCE FAVORS THIS SCENARIO AS WELL, WITH MEDIUM
PROBABILITIES OF THE DENSE FOG FURTHER EXPANDING TO THE EAST YET
THIS MORNING. WE WILL MONITOR OBSERVATIONAL TRENDS IN CASE ANY
EXPANSION OF THE DENSE FOG ADVISORY IS NEEDED, E.G., INTO
BURLEIGH AND EMMONS COUNTIES.
FOR LATER TODAY, WE EXPECT STRATUS AND FOG TO ERODE/DISSIPATE IN
SOUTHWESTERN ND THIS AFTERNOON AS LOW-LEVEL WIND FIELDS INCREASE
IN ADVANCE OF AN UPSTREAM SHORTWAVE TROUGH. THIS, COMBINED WITH
A WARM AIR MASS ALOFT IN A SOUTHWEST FLOW REGIME MEANS THAT HIGH
TEMPERATURES TODAY ARE FORECAST TO BE WELL INTO THE 40S F IF
NOT AROUND 50 F IN SOUTHWESTERN ND, E.G., FOR THE BEACH,
DICKINSON, BOWMAN, AND HETTINGER AREAS. HOW FAR NORTH AND EAST
STRATUS AND FOG IS ABLE TO ERODE IS SOMEWHAT UNCERTAIN, BUT THE
OVERALL AIR MASS CHARACTERISTICS AND SLOWLY SHALLOWING LOW-LEVEL
MOISTURE DO SUPPORT HIGHS EXCEEDING 32 F IN SOUTH CENTRAL ND,
INCLUDING IN THE AREAS THAT RECEIVED FREEZING RAIN YESTERDAY.
GUIDANCE WOULD SUGGEST THAT FOG MAY PERSIST IN SOME FASHION IN
NORTHWEST AND NORTH CENTRAL ND INTO THE JAMES RIVER VALLEY
THROUGH THE DAY, THOUGH SLOW WARMING OF THE BOUNDARY LAYER
(ALBEIT WITH HIGHS IN THOSE AREAS MAINLY IN THE MID/UPPER 20S F)
IS APT TO RESULT IN INCREASING VISIBILITIES AFTER 18 UTC.
WE HAVE A DRY FORECAST IN PLACE AREA-WIDE TODAY, BUT BY THIS
EVENING A LOW, 20 PERCENT CHANCE OF FREEZING RAIN EXISTS IN FAR
NORTHWEST AND NORTH CENTRAL ND, NEAR THE CANADIAN BORDER. THAT
LOW CHANCE OF LIGHT FREEZING RAIN CONTINUES IN THOSE AREAS INTO
THE OVERNIGHT HOURS. THAT IS SUPPORTED BY LOW- AND MIDLEVEL WARM
AIR ADVECTION NEAR A SHARPENING MIDLEVEL WARM FRONTAL ZONE, WITH
INCREASING DIFFERENTIAL CYCLONIC VORTICITY ADVECTION ALOFT GIVEN
HEIGHT FALLS AND STRENGTHENING/SHARPENING SOUTHWEST FLOW ALOFT.
FORECAST SOUNDINGS NEAR THE CANADIAN BORDER DISPLAY A WARM NOSE
ALOFT FROM +4 TO + 7 C ATOP SUB-FREEZING SURFACE TEMPERATURES IN
SUPPORT OF A CONDITIONAL FREEZING RAIN SCENARIO. HOWEVER, IT IS
VERY IMPORTANT TO POINT OUT THAT THOSE FORECAST SOUNDINGS ALSO
DISPLAY A DEEP DRY LAYER ALOFT, WHICH IS WHY MOST MODEL GUIDANCE
FAILS TO SIMULATE SIGNIFICANT PRECIPITATION ON THE NORTH DAKOTA
SIDE OF THE U.S./CANADIAN BORDER, AND WHY OUR PRECIPITATION
CHANCES ARE ONLY AROUND 20 PERCENT AT THIS JUNCTURE.
ONE OTHER FEATURE WORTH NOTING TONIGHT IS A STRONG UPPER-LEVEL
JET STREAK ON THE ORDER OF 120-140 KT, WHICH WILL HAVE ITS LEFT
EXIT REGION FOCUSED IN WESTERN AND CENTRAL ND. WHILE SIGNIFICANT
DRY AIR IS EXPECTED ALOFT, THIS PRESENTS A LOW, BUT NON-ZERO
(APPROXIMATELY 10 PERCENT) CHANCE OF LIGHT PRECIPITATION
FURTHER SOUTH INTO SOUTHWEST AND CENTRAL ND OVERNIGHT TONIGHT.
THESE ODDS ARE TOO LOW TO EVEN MENTION IN THE OFFICIAL FORECAST
AT THIS JUNCTURE, BUT THE 00 AND TO A LESSER DEGREE 06 UTC HRRR
CYCLES CAPTURE THIS IN SIMULATING SOME LIGHT PRECIPITATION
MOVING THROUGH SOUTHWEST AND INTO CENTRAL ND TONIGHT. THIS WILL
BE A LOW PROBABILITY, HIGHLY-CONDITIONAL SCENARIO CONTINGENT ON
SUFFICIENT SATURATION THAT'S MORE THAN SIMULATED BY MOST MODELS,
BUT ONE THAT WOULD BE MANIFEST AS LIGHT FREEZING RAIN IF IT DID
COME TO FRUITION. AGAIN, THOUGH, THIS IS A LOW PROBABILITY
SCENARIO THAT'S TOO SMALL TO EVEN BE IN THE OFFICIAL FORECAST
AT THIS TIME.
OTHERWISE, PATCHY TO AREAS OF FOG MAY PERSIST AND/OR REDEVELOP
IN CENTRAL ND AND THE JAMES RIVER VALLEY TONIGHT, THOUGH WINDS
JUST ABOVE THE SURFACE ARE FORECAST TO INCREASE AND VEER WITH A
DRYING TENDENCY SUCH THAT THE PROSPECTS FOR PERSISTENT AND DENSE
FOG MAY ACTUALLY BE GREATEST IN THE EVENING BEFORE DECREASING
AFTER 06 UTC. AT THIS TIME WE ARE SIMPLY MENTIONING PATCHY TO
AREAS OF FOG IN THE FORECAST TONIGHT INTO SATURDAY MORNING.
ON SATURDAY, HIGHS ARE FORECAST TO RANGE FROM THE TEENS AND 20S
F IN NORTHWEST AND NORTH CENTRAL ND, TO THE LOWER 40S IN
SOUTHWEST ND. HOWEVER, THE MAIN FEATURE OF INTEREST WILL BE THE
LATE-DAY AND EVENING PASSAGE OF AN ARCTIC COLD FRONT AND STRONG
SHORTWAVE TROUGH ALOFT. MEDIUM TO HIGH CHANCES OF LIGHT SNOW ARE
EXPECTED TO ACCOMPANY THE FRONTAL PASSAGE CENTERED ON SATURDAY
NIGHT GIVEN THE FRONTAL FORCING AND THERMAL PROFILES THAT COOL
INTO THE DENDRITIC GROWTH ZONE. HOWEVER, ANY ACCUMULATIONS
WOULD BE MINOR. STRONG LOW-LEVEL COLD AIR ADVECTION IS EXPECTED
WITH THE FRONTAL PASSAGE, AND AT LEAST MODERATE SURFACE PRESSURE
RISES ARE ALSO EXPECTED, FAVORING A PERIOD OF WIND GUSTS UP TO
AROUND 40 MPH. THE CURRENT SUITE OF GUIDANCE, INCLUDING RECENT
FORECAST EFI VALUES, SUGGEST THE ODDS OF REACHING WIND ADVISORY
CRITERIA WITH THE FRONTAL PASSAGE ARE LOW TO MEDIUM. THE ARRIVAL
OF ARCTIC AIR MAY RESULT IN WIND CHILLS AROUND -30 F IN PARTS
OF THE AREA SATURDAY NIGHT THROUGH MONDAY MORNING, ESPECIALLY
IN NORTHERN PARTS OF THE STATE.
COLD ARCTIC AIR IS FORECAST AREA-WIDE ON SUNDAY WITH HIGHS ONLY
IN THE SINGLE DIGITS ABOVE ZERO IN MOST AREAS, WITH THE SPREAD
IN ENSEMBLE GUIDANCE LOW IN THAT TIMEFRAME. NORTHWEST FLOW ALOFT
IS EXPECTED TO DEVELOP DURING THE EARLY AND MIDDLE PARTS OF NEXT
WEEK, WITH A LOW-LEVEL BAROCLINIC ZONE AND ASSOCIATED GRADIENT/
SHARP CONTRAST IN SURFACE TEMPERATURES ACROSS THE REGION. THIS
BECOMES VERY PRONOUNCED BY WEDNESDAY (NEW YEARS EVE), WHEN THE
ENSEMBLE 25TH-75TH PERCENTILE SPREAD IN HIGH TEMPERATURES
ACROSS MOST OF THE AREA REMAINS EXTREME, ON THE ORDER OF THIRTY
TO FORTY DEGREES, RANGING FROM HIGHS AROUND -5 F TO +35 F. THIS
STEMS FROM HOW SHARP AND PROLONGED NORTHWEST FLOW REMAINS, WHICH
ITSELF IS TIED TO HOW QUICKLY A TROUGH IN THE EASTERN PACIFIC
OCEAN PROGRESSES EASTWARD. ENSEMBLE CLUSTERS SUGGEST THERE'S A
60% PROBABILITY OF THE MORE PROLONGED NORTHWEST FLOW PERSISTING
DUE TO A MORE SLOWLY-APPROACING UPSTREAM TROUGH, WHICH WOULD
RESULT IN A COLDER SCENARIO BY MIDWEEK, AND A 40% PROBABILITY OF
THE WARMER SCENARIO OCCURRING. REGARDLESS, IT'S IMPORTANT TO
NOTE THAT THE OFFICIAL FORECAST LARGELY REPRESENTS THE MEAN OF
AN ATYPICALLY LARGE SPREAD IN POTENTIAL OUTCOMES WITH REGARD TO
TEMPERATURES BY THE MIDDLE TO LATTER PARTS OF NEXT WEEK. LOW TO
MEDIUM SNOW CHANCES ALSO EXIST IN THE EARLY AND MIDDLE PARTS OF
NEXT WEEK GIVEN THE PRESENCE OF THE LOW- AND MIDLEVEL FRONTAL
ZONE ACROSS THE AREA, ALBEIT WITH THE SAME UNCERTAINTY IN ITS
LOCATION, AND ALSO TIMING OF ANY IMPULSES THAT WOULD GENERATE
MORE FOCUSED PRECIPITATION ALONG THE COOL SIDE OF THE BOUNDARY.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 359 AM CST FRI DEC 26 2025
WIDESPREAD FOG IS EXPECTED ACROSS MUCH OF NORTHWEST AND CENTRAL
ND THROUGH THROUGH THIS MORNING, WITH PATCHY FOG ALSO IMPACTING
PARTS OF SOUTHWEST ND. SOME PARTS OF CENTRAL ND MAY SEE LOW
STRATUS AND FOG PERSIST THROUGH MOST OF THE 06Z TAF PERIOD.
WITHIN THE FOG, EXPECT IFR-LIFR CEILINGS AND VISIBILITIES.
SURFACE WINDS WILL BE GENERALLY LIGHT THROUGH THE PERIOD, WITH A
TREND TOWARD A SOUTHERLY DIRECTION ON FRIDAY.
BIS WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL NOON CST /11 AM MST/ TODAY FOR NDZ001-
002-009-010-017>021-034-042-045.
DISCUSSION...CJS
AVIATION...TWH/CJS
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