528
FXUS63 KBIS 281002
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
402 AM CST SUN DEC 28 2025
KEY MESSAGES
- SNOW AND BLOWING SNOW WITH SIGNIFICANTLY REDUCED VISIBILITY
TODAY INTO EARLY THIS EVENING IN FAR SOUTH CENTRAL AND
SOUTHEAST NORTH DAKOTA, INCLUDING THE JAMES RIVER VALLEY.
- WINDY AND COLD TODAY, WITH WIND CHILLS FROM 20 BELOW TO 30
BELOW ZERO.
- DECREASING WINDS TONIGHT, BUT STILL COLD WITH LOWS 5 BELOW
ZERO TO 15 BELOW ZERO.
DISCUSSION
ISSUED AT 402 AM CST SUN DEC 28 2025
WINDY AND COLD WEATHER IS EXPECTED TODAY, WITH SNOW AND BLOWING
SNOW IMPACTS IN PARTS OF SOUTH CENTRAL ND INTO THE JAMES RIVER
VALLEY. CONTINUED COLD TEMPERATURES ARE EXPECTED TONIGHT, BUT
WINDS WILL DIMINISH. THE EARLY-WEEK FORECAST WILL BE RELATIVELY
QUIET WITH NO IMPACTS EXPECTED, THOUGH BY MIDWEEK, MEDIUM
CHANCES OF SNOW RETURN TO THE FORECAST.
EARLY THIS MORNING A BAND OF MODERATE SNOW CONTINUES TO SLOWLY
PROGRESS THROUGH CENTRAL ND, WITH VISIBILITIES OCCASIONALLY AS
LOW AS 1/2SM, BUT MORE COMMONLY IN THE 1-2SM RANGE, WITH SNOW
ACCUMULATIONS ON THE ORDER OF 1-2 INCHES BEING OBSERVED SO FAR.
THIS SNOW BAND DOES APPEAR TO BE MOVING A BIT MORE SLOWLY EAST
THAN EXPECTED EARLIER, WHICH MAY BE THE RESULT OF THE MIDDLE-
AND UPPER-LEVEL FLOW BEING MORE SOUTHERLY AHEAD OF THE UPPER-
LEVEL LOW WHICH IS LOCATED IN NORTHEAST MT AT THIS HOUR. WATER
VAPOR IMAGERY SUGGESTS THAT LOW MAY BE A TOUCH FURTHER SOUTH
THAN MANY MODEL SIMULATIONS HAD SUGGESTED PREVIOUSLY. THAT IN
TURN MAY BE RESULTING IN THE MORE MERIDIONAL (SOUTHERLY) FLOW
ALOFT DOWNSTREAM AND A SLIGHTLY SLOWER EASTWARD PROGRESSION OF
THE SNOW BAND, WHICH IS BEING DRIVEN BY AN AREA OF STRONG
MIDLEVEL FRONTOGENESIS. THE GUIDANCE THAT APPEARS TO HAVE THE
BEST HANDLE ON THE PLACEMENT OF THE UPPER-LEVEL LOW SUPPORTS
OBSERVATIONAL TRENDS IN SUGGESTING THE BAND OF MODERATE SNOW
WILL MOVE THROUGH THE JAMES RIVER VALLEY THROUGH MID MORNING,
WITH REDUCED VISIBILITIES IN FALLING AND BLOWING SNOW EVEN IF
TOTAL ACCUMULATIONS REMAIN ON THE ORDER OF 1 TO 3 INCHES. AS THE
UPPER-LEVEL LOW CONTINUES TO MOVE SOUTHEAST, REACHING SOUTHEAST
SD BY THIS AFTERNOON, AN AREA OF MIDLEVEL WARM AIR ADVECTION
AND FORCING ON ISENTROPIC SURFACES TO ITS NORTH SUGGESTS LIGHT
SNOW WILL CONTINUE AND/OR "WRAP-AROUND" ACROSS THE JAMES RIVER
VALLEY THROUGH THE DAY, EVEN AFTER THE INITIAL, FRONTOGENESIS-
DRIVEN BAND OF SNOW MOVES OUT OF THE AREA DURING THE MORNING.
NBM PROBABILITIES OF 1 INCH OF SNOWFALL IN THE JAMES RIVER
VALLEY ARE HIGH (70+ PERCENT), AND OF REACHING 2 INCHES ARE
MEDIUM TO HIGH (ON THE ORDER OF 50 TO 70 PERCENT). AS WILL BE
DISCUSSED FURTHER BELOW, WHERE FALLING SNOW OVERLAPS WITH
STRONG WINDS IN THE JAMES RIVER VALLEY AND PARTS OF SOUTH
CENTRAL ND, SIGNIFICANT BLOWING SNOW IS EXPECTED TODAY AND INTO
THIS EVENING.
WE ALSO INCLUDED LOW CHANCES OF SNOWFALL IN CENTRAL ND TODAY IN
RESPECT TO UNCERTAINTY WITH HOW FAR WEST THE "WRAP-AROUND"
LIGHT SNOWFALL WILL EXTEND, AND IN PARTS OF WESTERN ND THIS
MORNING AS THE UPPER-LEVEL LOW ITSELF CROSSES THAT PART OF THE
STATE.
A STRONG SURFACE PRESSURE GRADIENT IS FORECAST ACROSS THE STATE
TODAY AS AN ARCTIC HIGH PRESSURE SYSTEM ON THE ORDER OF 1040 MB
APPROACHES FROM SOUTHWESTERN CANADA, AND AS A STRONG SURFACE LOW
PRESSURE SYSTEM RAPIDLY DEEPENS WHILE MOVING ACROSS THE MIDWEST
AND INTO THE GREAT LAKES. THE RESULT WILL BE A WINDY DAY, WITH
FORECAST SOUNDINGS SUGGESTING MIXING OF 30 TO 40 KT WINDS AT THE
TOP OF THE BOUNDARY LAYER. BLOWING SNOW MODEL OUTPUT SUGGESTS
SIGNIFICANT BLOWING SNOW IN PARTS OF SOUTH CENTRAL ND AND THE
JAMES RIVER VALLEY, WITH VISIBILITIES OF 1/2SM OR OCCASIONALLY
AS LOW AS 1/4SM EXPECTED WHERE FALLING SNOW COMBINES WITH STRONG
WINDS. WITHOUT SIGNIFICANT PRE-EXISTING SNOWPACK, THE BLOWING
SNOW IMPACTS WILL BE HIGHLY SENSITIVE TO FALLING SNOW, AND HOW
MUCH SNOW FALLS GIVEN THE RELATIVELY LOW ACCUMULATIONS THAT WE
ARE EXPECTING. THIS DOES RAISE SOME UNCERTAINTY IN THE FORECAST,
BUT WE HAVE HIGH CONFIDENCE IN ADVISORY-LEVEL BLOWING SNOW
IMPACTS WHERE THE WINTER WEATHER ADVISORY HAS BEEN ISSUED. A LOW
PROBABILITY DOES EXIST FOR BLIZZARD CONDITIONS TO DEVELOP IN
PARTS OF THE ADVISORY AREA, IF SNOWFALL RATES BECOME HIGH ENOUGH.
WHILE THAT'S A LOW-PREDICTABILITY OUTCOME, IT'S A SCENARIO WE
WILL BE MONITORING FOR CLOSELY IN OBSERVATIONAL TRENDS.
WE DID OPT TO EXTEND THE WIND ADVISORY IN FAR SOUTHWEST AND FAR
SOUTH CENTRAL ND THROUGH THE DAY, WHERE THE SURFACE PRESSURE
GRADIENT REMAINS STRONG ENOUGH FOR MARGINAL ADVISORY-LEVEL WINDS
TODAY. FORECAST SOUNDINGS ARE MARGINAL FOR ADVISORY-LEVEL GUSTS,
AND WE DID CONSIDER ALLOWING THE ADVISORY TO EXPIRE AS SCHEDULED
EARLY THIS MORNING, BUT OPTED TO EXTEND IT GIVEN RECENT TRENDS
IN OBSERVED WINDS.
WE ALSO EXPANDED THE COLD WEATHER ADVISORY SOUTH TO INCLUDE ALL
OF WESTERN ND THROUGH THE MORNING, WITH OBSERVED WIND CHILLS ON
THE ORDER OF -30 F BECOMING WIDESPREAD AS OF 09 UTC. WIND CHILLS
ARE FORECAST TO SLOWLY RISE OUT OF ADVISORY RANGE BY AFTERNOON,
BUT IT'S POSSIBLE SOME PART OF THAT ADVISORY WILL NEED TO BE
EXTENDED LATER PENDING OBSERVED TRENDS.
HIGHS TODAY ARE FORECAST TO ONLY RANGE FROM ZERO TO 10 ABOVE
ZERO. WE EXPECT LOWS TONIGHT TO RANGE FROM 5 BELOW TO 15 BELOW
ZERO, LOWEST IN WESTERN AND NORTH CENTRAL ND CLOSEST TO THE
SURFACE RIDGE AXIS THAT IS FORECAST TO MOVE FROM WESTERN AND
INTO CENTRAL ND OVERNIGHT. THE AIR MASS WILL MODIFY SOMEWHAT
BY TONIGHT AS THE UPPER-LEVEL LOW EXISTS THE AREA, BUT WE DID
LEAN ON THE COLDER EDGE (NEAR THE 25TH PERCENTILE) OF ENSEMBLE
MEMBERSHIP FOR FORECAST LOWS TONIGHT. THAT'S BASED ON THE
POSITION OF THE SURFACE RIDGE AXIS, EXPECTED EFFICIENT
RADIATIONAL COOLING, AND OBSERVED TEMPERATURES UNDERNEATH THE
RIDGE AXIS UPSTREAM IN ALBERTA AND SASKATCHEWAN THAT ARE IN THE
-10 TO -20 F RANGE. IT IS POSSIBLE THAT SOME AREAS OF WESTERN
AND CENTRAL ND MAY BE EVEN COLDER THAN FORECAST TONIGHT BASED ON
THOSE UPSTREAM OBSERVATIONS. WHILE WINDS WILL BE DIMINISHING
TONIGHT, AND WILL BECOME LIGHT IN WESTERN ND, WE MAY NEED TO
EXTEND OR RE-ISSUE ANOTHER COLD WEATHER ADVISORY SINCE EVEN
LIGHT WINDS MAY CAUSE WIND CHILLS IN THE -30 F RANGE WHERE
ACTUAL AIR TEMPERATURES ARE COLDEST.
NORTHWEST FLOW ALOFT IS EXPECTED TO PREVAIL FOR MUCH OF THE
UPCOMING WEEK ACROSS THE NORTHERN PLAINS IN BETWEEN A STRONG
HUDSON BAY LOW AND RIDGING IN THE WESTERN UNITED STATES. THE
SYNOPTIC-SCALE PATTERN HAS STRONG CONFIDENCE FROM ENSEMBLE
GUIDANCE THROUGH MIDWEEK, BUT THE REGIME IS EXPECTED TO YIELD A
STRONG BAROCLINIC ZONE AND RELATED TEMPERATURE CONTRAST ACROSS
THE REGION. THE EXACT PLACEMENT OF THAT FRONTAL ZONE CARRIES
LOWER PREDICTABILITY, AND WILL BE INFLUENCED BY WEAK IMPULSES
EMBEDDED IN THE NORTHWEST FLOW. NBM GUIDANCE HAS RELATIVELY LOW
SPREAD MONDAY AND ESPECIALLY TUESDAY, WHEN A GENERAL WARMING
TREND IS FORECAST. HIGHS BY TUESDAY ARE BROADLY FORECAST TO BE
IN THE 30S F ACROSS MUCH OF THE AREA, AGAIN, WITH LOW SPREAD IN
ENSEMBLE MEMBERSHIP, RESULTING IN HIGH CONFIDENCE IN THAT PART
OF THE FORECAST. HOWEVER, BEGINNING WEDNESDAY THE SPREAD IN NBM
GUIDANCE REMAINS LARGE, ON THE ORDER OF 20 DEGREES OR MORE. AS
AN EXAMPLE, AT BISMARCK, THE REASONABLE RANGE OUTCOMES FOR HIGH
TEMPERATURES ON WEDNESDAY (NEW YEARS EVE) IS FROM 8 F TO 31 F.
SIMILAR SPREADS IN TEMPERATURE FORECASTS THEN CONTINUE THROUGH
THE LATTER PART OF THE WEEK, BOTH DUE TO UNCERTAINTY IN EXACT
LOCATION OF THE FRONTAL ZONE, AND DUE TO UNCERTAINTY IN HOW
AMPLIFIED THE NORTHWEST FLOW ALOFT WILL BE. THAT'S RELATED TO
THE PROGRESSION OF AN UPSTREAM TROUGH IN THE PACIFIC OCEAN. THE
BOTTOM LINE IS THAT THE TEMPERATURE FORECAST IS MORE UNCERTAIN
THAN NORMAL FROM WEDNESDAY ONWARD, AND SHOULD BE EXPECTED TO
CHANGE FOR SOME DAYS AND LOCATIONS WITH LATER FORECASTS.
PRECIPITATION-WISE, ENSEMBLE GUIDANCE CONTINUES TO HIGHLIGHT THE
TUESDAY NIGHT AND WEDNESDAY TIMEFRAME FOR MEDIUM PROBABILITIES
OF SNOWFALL AS AN IMPULSE CROSSES THE REGION IN NORTHWEST FLOW.
WE WOULD EXPECT AN AXIS OF SNOWFALL ALONG AND TO THE COOL
(NORTH) SIDE OF THE BAROCLINIC ZONE, WHEREVER IT ENDS UP EXACTLY
BY THAT TIMEFRAME. NBM PROBABILITIES OF 1 INCH OF SNOWFALL ARE
HIGH IN NORTH CENTRAL ND AND THE JAMES RIVER VALLEY IN THE TIME
PERIOD CENTERED ON WEDNESDAY, WITH MEDIUM PROBABILITIES OF 2
INCHES OR MORE OF SNOWFALL. THOSE PROBABILITIES DIMINISH FURTHER
TO THE SOUTHWEST PART OF THE STATE. OTHERWISE, LOW CHANCES OF
SNOW ARE ALSO INCLUDED IN THE FORECAST NEXT WEEKEND BASED ON A
CONSENSUS OF ENSEMBLE GUIDANCE, TOO.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 402 AM CST SUN DEC 28 2025
A BAND OF SNOW WITH IFR TO LOCAL LIFR VISIBILITY AND MAINLY MVFR
CEILINGS WILL CONTINUE MOVING ACROSS CENTRAL ND AND THE JAMES
RIVER VALLEY OVERNIGHT. CONDITIONS WILL IMPROVE IN WESTERN ND
AND PARTS OF CENTRAL ND AS THE SNOW BAND MOVES EAST, BUT SOME
MVFR CEILINGS REMAIN POSSIBLE BEHIND THE SNOW BAND INTO SUNDAY.
SNOW AND BLOWING SNOW WILL LINGER IN THE JAMES RIVER VALLEY
INCLUDING AT KJMS INTO SUNDAY AS THE SYSTEM SLOWS ITS
PROGRESSION. NORTHWEST WINDS GUSTING AS HIGH AS 30-40 KT ARE
EXPECTED AREA-WIDE THROUGH SUNDAY AFTERNOON. THE WIND COULD
COMBINE WITH FRESH SNOWFALL TO PRODUCE VISIBILITY RESTRICTIONS
FROM BLOWING SNOW, ESPECIALLY AT KJMS AND SURROUNDING AREAS.
BIS WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY UNTIL NOON CST /11 AM MST/ TODAY FOR
NDZ001-002-009-010-017-018-031>033-040-041-043-044.
WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR NDZ023-
025-036-037-046>048-050-051.
WIND ADVISORY UNTIL 5 PM CST /4 PM MST/ THIS AFTERNOON FOR
NDZ040>045.
DISCUSSION...CJS
AVIATION...CJS
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